Effects of lighting pattern and photoperiod on egg production and egg quality of a native chicken under free-range condition

Effects of lighting pattern and photoperiod on egg production and egg quality of a native chicken... ABSTRACT The paper aimed to study the effects of lighting pattern and photoperiod alone and in combination on egg production, egg quality in Beijing You Chicken (BYC). A total of 630 19-wk-old BYC laying hens were randomly allocated to 6 groups with 105 birds each, 3 replicates per group, reared in individually lit floor pens with separate outdoor areas. A 2 × 3 factorial experiment (2 lighting patterns: continuous and intermittent lighting; 3 photoperiods: 16, 14, 12 h) was arranged, including 16L:8D (6:00 to 22:00) for group 1; 12L:2D:4L:6D (6:00 to 18:00, 20:00 to 24:00) for group 2; 14L:10D (6:00 to 20:00) for group 3; 10L:2D:4L:8D (6:00 to 16:00, 18:00 to 22:00) for group 4; 12L:12D (6:00 to 18:00) for group 5, and 8L:4D:4L:8D (6:00 to 14:00, 18:00 to 22:00) for group 6, respectively. Egg production parameters were calculated for 22 to 43, 44 to 57, and 22 to 57 wk, and egg quality parameters were measured at the end of 37 and 57 wk. The results showed that the egg production of BYC was not significantly affected by lighting pattern, photoperiod alone, or in combination during 22 to 43 and 22 to 57 wk (P > 0.05), but average feed intake in 12 h groups was significantly higher than those in 14 and 16 h groups during 22 to 43 and 22 to 57 wk (P < 0.05). Egg mass and feed egg ratio were significantly affected by lighting pattern, photoperiod alone, and in combination during 44 to 57 wk (P < 0.05). Egg mass was significantly higher (P = 0.05) and feed egg ratio was significantly lower (P = 0.03) in continuous groups than in intermittent groups. There were significant effects for eggshell thickness, albumen height, haugh unit, and egg grade by lighting pattern alone (P < 0.05) at 37 wk. The study suggested that 1) the egg production was not significantly affected by lighting pattern alone during 22 to 57 wk (P > 0.05), but the photoperiod significantly affected average feed intake (P < 0.05); 2) continuous lighting is better for the egg production during 44 to 57 wk, and intermittent lighting is better for egg quality of the native bird at 37 wk; 3) 12 h lighting is enough for meeting the requirement of the native chicken during the laying period; (4) no change in photoperiod from the rearing to the production phase (12 to 12 L) will have long-lasting effects on egg production or egg quality under the present condition. INTRODUCTION In recent years, people have paid more attention to the egg quality, which is related to various external and internal qualities that are measured in eggs (Koelkebeck 1999). Egg quality is important to the egg industry worldwide. Factors affecting egg quality include strain, age, nutritional factors, stress, production system, etc. (Juliet 2004). There are clear differences in eggshell quality between modern commercial birds and traditional laying fowl (Hocking et al., 2003), and external quality such as egg shape, egg weight, etc. (Zhang et al., 2009). Beijing You Chicken (BYC), a dual-purpose native chicken used for meat and egg production in Beijing district, is well known for its characteristic appearance (having crest, beard, shank feathers, and 5-toes) and high quality of meat and egg (Liu and Xu 2001) was listed as one of the most important chicken breeds by Ministry of Agriculture, China (National Livestock and Poultry Genetic Resources Committee 2017). A lot of companies and farms emerged that are especially engaged in rearing BYC and most farms are adapted to the free range system by using the orchard, hillside, and woods where the birds go outside for food and activities at daytime, and go back into the house to rest at night. Usually the male chicken will be sold out as meat-type chicken during 90 to 120 d, and the female will be reared as egg-laying hens. Compared with modern high-producing strains such as Hy-Line Brown, Lohmann Brown, etc., BYC has a lower egg output (150 to 170 eggs per year) but still are reared under a similar lighting schedule, e.g., continuous 16 h lighting during the egg-laying period. Shen et al. (2011) studied the effects of 4 kinds of lighting treatments (16L:8D,6:00 to 22:00; 12L:2D:4L:6D, 6:00 to 18:00, 20:00 to 24:00; 8L:4D:4L:8D, 8:00 to 16:00, 20:00 to 24:00; 16L:8D, 3:00 to 19:00) on the performance of BYC laying hens, and found that the intermittent 12 h lighting (8L:4D:4L:8D) had beneficial effects on the performance for the pre-laying and peak laying period. Tang et al. (2012) compared the effects of different lighting program on the performance of growing BYC (8 to 90 d of age), and found that the weight gain of the bird in continuous 16 h group (16L:8D) was better than in intermittent 18 h group (3L:1D). Our group adopted 6 kinds of photoperiodic treatments to study the egg laying of BYC during 20 to 61wk, and found that the egg-laying rate was significantly higher in intermittent 16 h group than in continuous 16 h group (Geng et al., 2014). Based on above, the present study aimed to study the effects of lighting pattern and photoperiod alone and in combination on egg production, egg quality of BYC under free-range condition, and provide some references for the appropriate lighting management of the bird. MATERIALS AND METHODS Experimental Design and Birds The experiment was conducted at BYC Breeding Farm, Daxing district, Beijing. Six hundred and thirty 19-wk-old commercial BYC laying hens having the same genetic origin were moved from the rearing room (keeping natural photoperiod 11 to 12 h) and randomly allocated to 6 experimental groups, 105 birds every group with 3 replicates, 35 birds per replicate (pen) under free-range condition. The birds were reared in individually lit floor pens with separate outdoor areas. The indoor density was about 6.8 birds/m2, and outdoor density was about 1.9 birds/m2. Nest boxes, perches, and rice husk litters were equipped in each pen. A 2 × 3 factorial experiment was arranged (2 lighting patterns: continuous and intermittent lighting; 3 photoperiods: 16, 14, 12 h), including 16L:8D (6:00 to 22:00) for group 1; 12L:2D:4L:6D (6:00 to 18:00. 20:00 to 24:00) for group 2; 14L:10D (6:00 to 20:00) for group 3; 10L:2D:4L:8D (6:00 to 16:00,18:00 to 22:00) for group 4; 12L:12D (6:00 to 18:00) for group 5; and 8L:4D:4L:8D (6:00 to 14:00,18:00 to 22:00) for group 6, respectively (see Table 1). In order to keep the same ranging time for the birds, the groups adopted the arrangement below: lights at 6:00 in the morning every day, birds fed 6:00 to 8:00, birds range freely 8:00 to 14:00, and return to their pens at 14:00 when the second feeding time begins. Special light-proof cloth and the light controller were used in each pen. Table 1. Experimental design and lighting treatments. Group Lighting pattern Photoperiod/(h) Lighting regimen 1 Continuous 16 16L:8D (6:00 to 22:00) 2 Intermittent 16 12L:2D:4L:6D (6:00 to 18:00, 20:00 to 24:00) 3 Continuous 14 14L:10D (6:00 to 20:00) 4 Intermittent 14 10L:2D:4L:8D (6:00 to 16:00, 18:00 to 22:00) 5 Continuous 12 12L:12D (6:00 to 18:00) 6 Intermittent 12 8L:4D:4L:8D (6:00 to 14:00, 18:00 to 22:00) Group Lighting pattern Photoperiod/(h) Lighting regimen 1 Continuous 16 16L:8D (6:00 to 22:00) 2 Intermittent 16 12L:2D:4L:6D (6:00 to 18:00, 20:00 to 24:00) 3 Continuous 14 14L:10D (6:00 to 20:00) 4 Intermittent 14 10L:2D:4L:8D (6:00 to 16:00, 18:00 to 22:00) 5 Continuous 12 12L:12D (6:00 to 18:00) 6 Intermittent 12 8L:4D:4L:8D (6:00 to 14:00, 18:00 to 22:00) View Large Table 1. Experimental design and lighting treatments. Group Lighting pattern Photoperiod/(h) Lighting regimen 1 Continuous 16 16L:8D (6:00 to 22:00) 2 Intermittent 16 12L:2D:4L:6D (6:00 to 18:00, 20:00 to 24:00) 3 Continuous 14 14L:10D (6:00 to 20:00) 4 Intermittent 14 10L:2D:4L:8D (6:00 to 16:00, 18:00 to 22:00) 5 Continuous 12 12L:12D (6:00 to 18:00) 6 Intermittent 12 8L:4D:4L:8D (6:00 to 14:00, 18:00 to 22:00) Group Lighting pattern Photoperiod/(h) Lighting regimen 1 Continuous 16 16L:8D (6:00 to 22:00) 2 Intermittent 16 12L:2D:4L:6D (6:00 to 18:00, 20:00 to 24:00) 3 Continuous 14 14L:10D (6:00 to 20:00) 4 Intermittent 14 10L:2D:4L:8D (6:00 to 16:00, 18:00 to 22:00) 5 Continuous 12 12L:12D (6:00 to 18:00) 6 Intermittent 12 8L:4D:4L:8D (6:00 to 14:00, 18:00 to 22:00) View Large The birds were fed commercial corn-soybean-based diets with 15.1% crude protein (CP), 11.20 MJ/kg metabolizable energy (ME), and 2.0% calcium during 19 to 21 wk, and with 15.5% CP, 11.08 MJ/kg ME, and 2.75% calcium during 22 to 57 wk. The incandescent lamps were used, and the bulbs were 2 m off the ground, and average light intensity was 10 lux. Appropriate temperature and moisture were manipulated. Under severe weather conditions such as thundering and haze days, the birds were confined inside the pen to reduce the stress. The study was performed in accordance with local ethical guidelines and met the requirement of the institutional animal care and use committee. Measurement and Methods Feed intake, egg numbers, and egg weight of each pen were recorded every day, and weekly average feed intake (AFI), egg-laying rate, egg mass (EM), feed egg ratio (FER), and mortality rate for each group were calculated for 22 to 43, 44 to 57, and 22 to 57 wk, and egg quality parameters at the end of 37 and 57 wk were measured and calculated, respectively. A total of 10 fresh eggs were randomly chosen from each replicate, totaled 30 eggs for each group. Egg weight (EW), haugh unit (HU), albumen height (AH), yolk color (YC), egg grade (EG), eggshell strength (ESS), eggshell thickness (EST), eggshell color (ESC), egg shape index (ESI), relative yolk weight (RYW), relative eggshell weight (RESW), and relative albumen weight (RAW) were measured and calculated within 24 h. Egg weight, AH, HU, YC, and EG were measured by using the Egg Multi Tester (Model EMT-7300, Robotmation Co., Ltd, Japan), Egg grade included AA, A, B, and C, represented as score of 3, 2, 1, and 0, respectively. Eggshell color was measured by using the TSS OCR-PS (Technical Services and Supplies, England). Eggshell thickness was measured by using the Echo-meter (Model ETG-1061A, Karl Deutsch, Germany). Egg shape index was measured by using Egg Shape Index Tester (FHK, Fujihira Industry Co., Ltd, Japan), Eggshell strength was measured by using the Egg Force Reader (Orka Food Technology Ltd., Israel). Lastly, yolk and albumen were separated by egg separator and each was weighed, and the RYW, RAW, and RESW were calculated accordingly. Statistical Analyses The data were analyzed statistically using SPSS 16.0 Software for Windows (SPSS Inc. Chicago, IL). General linear model was used to analyze the main effects of lighting pattern and photoperiod alone, and the combination between lighting pattern and photoperiod. Duncan's test was used for multiple comparisons. The percentage was arcsine transformed before analysis. P < 0.05 was regarded as statistically significant. RESULTS Table 2 shows that egg production during 22 to 43 wk was not significantly affected by lighting pattern alone (P > 0.05). Egg-laying rate, EM, FER, and mortality rate were not significantly affected by photoperiod alone (P > 0.05), but AFI of 12 h was significantly higher than those in 14 and 16 h groups (P = 0.01). There were no significant effects on egg production of the native birds for the combination of lighting pattern and photoperiod during 22 to 43 wk (P > 0.05). Table 2. Effects of lighting pattern and photoperiod on egg production of Beijing You Chicken during 22 to 43 wks. Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.86 58.02 2.88 3.78 0.13 Intermittent 16 10.92 54.83 2.80 3.90 0 Continuous 14 10.69 56.41 2.72 3.93 0.09 Intermittent 14 10.84 55.30 2.73 3.97 0.09 Continuous 12 11.36 48.90 2.56 4.44 0.04 Intermittent 12 11.57 55.88 2.87 4.03 0.13 SEM 0.09 1.32 0.07 0.49 0.02 GLM analysis Arcsine transformation Lighting pattern Continuous 10.97 54.45 2.72 5.37 0.09 Intermittent 11.11 55.34 2.80 5.25 0.07 P value 0.46 0.74 0.58 0.74 0.90 Photoperiod 16 10.89b 56.43 2.84 4.76 0.07 14 10.76b 55.85 2.73 5.68 0.09 12 11.47a 52.39 2.72 5.49 0.09 P value 0.01 0.40 0.76 0.91 0.71 Lighting pattern × Photoperiod P value 0.94 0.25 0.53 0.16 0.96 Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.86 58.02 2.88 3.78 0.13 Intermittent 16 10.92 54.83 2.80 3.90 0 Continuous 14 10.69 56.41 2.72 3.93 0.09 Intermittent 14 10.84 55.30 2.73 3.97 0.09 Continuous 12 11.36 48.90 2.56 4.44 0.04 Intermittent 12 11.57 55.88 2.87 4.03 0.13 SEM 0.09 1.32 0.07 0.49 0.02 GLM analysis Arcsine transformation Lighting pattern Continuous 10.97 54.45 2.72 5.37 0.09 Intermittent 11.11 55.34 2.80 5.25 0.07 P value 0.46 0.74 0.58 0.74 0.90 Photoperiod 16 10.89b 56.43 2.84 4.76 0.07 14 10.76b 55.85 2.73 5.68 0.09 12 11.47a 52.39 2.72 5.49 0.09 P value 0.01 0.40 0.76 0.91 0.71 Lighting pattern × Photoperiod P value 0.94 0.25 0.53 0.16 0.96 Values with different letter superscripts in the same column mean significant difference (P < 0.05). AFI = average feed intake; FER = feed egg ratio. View Large Table 2. Effects of lighting pattern and photoperiod on egg production of Beijing You Chicken during 22 to 43 wks. Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.86 58.02 2.88 3.78 0.13 Intermittent 16 10.92 54.83 2.80 3.90 0 Continuous 14 10.69 56.41 2.72 3.93 0.09 Intermittent 14 10.84 55.30 2.73 3.97 0.09 Continuous 12 11.36 48.90 2.56 4.44 0.04 Intermittent 12 11.57 55.88 2.87 4.03 0.13 SEM 0.09 1.32 0.07 0.49 0.02 GLM analysis Arcsine transformation Lighting pattern Continuous 10.97 54.45 2.72 5.37 0.09 Intermittent 11.11 55.34 2.80 5.25 0.07 P value 0.46 0.74 0.58 0.74 0.90 Photoperiod 16 10.89b 56.43 2.84 4.76 0.07 14 10.76b 55.85 2.73 5.68 0.09 12 11.47a 52.39 2.72 5.49 0.09 P value 0.01 0.40 0.76 0.91 0.71 Lighting pattern × Photoperiod P value 0.94 0.25 0.53 0.16 0.96 Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.86 58.02 2.88 3.78 0.13 Intermittent 16 10.92 54.83 2.80 3.90 0 Continuous 14 10.69 56.41 2.72 3.93 0.09 Intermittent 14 10.84 55.30 2.73 3.97 0.09 Continuous 12 11.36 48.90 2.56 4.44 0.04 Intermittent 12 11.57 55.88 2.87 4.03 0.13 SEM 0.09 1.32 0.07 0.49 0.02 GLM analysis Arcsine transformation Lighting pattern Continuous 10.97 54.45 2.72 5.37 0.09 Intermittent 11.11 55.34 2.80 5.25 0.07 P value 0.46 0.74 0.58 0.74 0.90 Photoperiod 16 10.89b 56.43 2.84 4.76 0.07 14 10.76b 55.85 2.73 5.68 0.09 12 11.47a 52.39 2.72 5.49 0.09 P value 0.01 0.40 0.76 0.91 0.71 Lighting pattern × Photoperiod P value 0.94 0.25 0.53 0.16 0.96 Values with different letter superscripts in the same column mean significant difference (P < 0.05). AFI = average feed intake; FER = feed egg ratio. View Large Table 3 shows that AFI, egg-laying rate, and mortality rate were not significantly affected by lighting pattern, photoperiod alone, or in combination during 44 to 57 wk (P > 0.05), but EM and FER were significantly affected by lighting pattern, photoperiod alone, and in combination (P < 0.05). Egg mass was significantly higher (2.97 > 2.87 kg, P = 0.05) and FER was significantly lower (3.64 < 3.78, P = 0.03) in continuous groups than in intermittent groups. Egg mass was significantly higher (P = 0.02) and FER was significantly lower (P = 0.02) in 16 and 12 h groups than in 14 h groups. Egg mass was significantly higher (P = 0.04) and FER was significantly lower (P = 0.02) in continuous 16 h and continuous 12 h groups than those in continuous 14 h, intermittent 14 h, and intermittent 12 h groups. Table 3. Effects of lighting pattern and photoperiod on egg production of Beijing You Chicken during 44 to 57 wk. Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.63 56.60 3.03 3.51 0 Intermittent 16 10.73 55.68 2.91 3.70 0 Continuous 14 10.74 54.56 2.79 3.87 0.22 Intermittent 14 11.00 53.37 2.86 3.77 0.07 Continuous 12 11.00 55.82 3.10 3.55 0.07 Intermittent 12 11.00 53.21 2.85 3.86 0.21 SEM 0.10 0.74 0.02 0.03 0.03 GLM analysis Arcsine transformation Lighting pattern Continuous 10.79 55.66 2.97a 3.64b 0.09 Intermittent 10.91 54.09 2.87b 3.78a 0.09 P value 0.54 0.29 0.05 0.03 0.99 Photoperiod 16 10.68 56.14 2.97a 3.61b 0 14 10.87 53.97 2.82b 3.82a 0.14 12 11.00 54.51 2.98a 3.71b 0.14 P value 0.42 0.46 0.02 0.02 0.11 Lighting pattern × photoperiod Continuous 16 h 10.63 56.60 3.03a 3.51c 0 Continuous 14 h 10.74 54.56 2.79b 3.87a 0.22 Continuous 12 h 11.00 55.82 3.10a 3.55c 0.07 Intermittent 16 h 10.73 55.68 2.91a,b 3.70b 0 Intermittent 14 h 11.00 53.37 2.86b 3.77b 0.07 Intermittent 12 h 11.00 53.21 2.85b 3.86a 0.21 P value 0.87 0.88 0.04 0.02 0.17 Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.63 56.60 3.03 3.51 0 Intermittent 16 10.73 55.68 2.91 3.70 0 Continuous 14 10.74 54.56 2.79 3.87 0.22 Intermittent 14 11.00 53.37 2.86 3.77 0.07 Continuous 12 11.00 55.82 3.10 3.55 0.07 Intermittent 12 11.00 53.21 2.85 3.86 0.21 SEM 0.10 0.74 0.02 0.03 0.03 GLM analysis Arcsine transformation Lighting pattern Continuous 10.79 55.66 2.97a 3.64b 0.09 Intermittent 10.91 54.09 2.87b 3.78a 0.09 P value 0.54 0.29 0.05 0.03 0.99 Photoperiod 16 10.68 56.14 2.97a 3.61b 0 14 10.87 53.97 2.82b 3.82a 0.14 12 11.00 54.51 2.98a 3.71b 0.14 P value 0.42 0.46 0.02 0.02 0.11 Lighting pattern × photoperiod Continuous 16 h 10.63 56.60 3.03a 3.51c 0 Continuous 14 h 10.74 54.56 2.79b 3.87a 0.22 Continuous 12 h 11.00 55.82 3.10a 3.55c 0.07 Intermittent 16 h 10.73 55.68 2.91a,b 3.70b 0 Intermittent 14 h 11.00 53.37 2.86b 3.77b 0.07 Intermittent 12 h 11.00 53.21 2.85b 3.86a 0.21 P value 0.87 0.88 0.04 0.02 0.17 a–cValues with different letter superscripts in the same column mean significant difference (P < 0.05). AFI = average feed intake; FER = feed egg ratio. View Large Table 3. Effects of lighting pattern and photoperiod on egg production of Beijing You Chicken during 44 to 57 wk. Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.63 56.60 3.03 3.51 0 Intermittent 16 10.73 55.68 2.91 3.70 0 Continuous 14 10.74 54.56 2.79 3.87 0.22 Intermittent 14 11.00 53.37 2.86 3.77 0.07 Continuous 12 11.00 55.82 3.10 3.55 0.07 Intermittent 12 11.00 53.21 2.85 3.86 0.21 SEM 0.10 0.74 0.02 0.03 0.03 GLM analysis Arcsine transformation Lighting pattern Continuous 10.79 55.66 2.97a 3.64b 0.09 Intermittent 10.91 54.09 2.87b 3.78a 0.09 P value 0.54 0.29 0.05 0.03 0.99 Photoperiod 16 10.68 56.14 2.97a 3.61b 0 14 10.87 53.97 2.82b 3.82a 0.14 12 11.00 54.51 2.98a 3.71b 0.14 P value 0.42 0.46 0.02 0.02 0.11 Lighting pattern × photoperiod Continuous 16 h 10.63 56.60 3.03a 3.51c 0 Continuous 14 h 10.74 54.56 2.79b 3.87a 0.22 Continuous 12 h 11.00 55.82 3.10a 3.55c 0.07 Intermittent 16 h 10.73 55.68 2.91a,b 3.70b 0 Intermittent 14 h 11.00 53.37 2.86b 3.77b 0.07 Intermittent 12 h 11.00 53.21 2.85b 3.86a 0.21 P value 0.87 0.88 0.04 0.02 0.17 Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.63 56.60 3.03 3.51 0 Intermittent 16 10.73 55.68 2.91 3.70 0 Continuous 14 10.74 54.56 2.79 3.87 0.22 Intermittent 14 11.00 53.37 2.86 3.77 0.07 Continuous 12 11.00 55.82 3.10 3.55 0.07 Intermittent 12 11.00 53.21 2.85 3.86 0.21 SEM 0.10 0.74 0.02 0.03 0.03 GLM analysis Arcsine transformation Lighting pattern Continuous 10.79 55.66 2.97a 3.64b 0.09 Intermittent 10.91 54.09 2.87b 3.78a 0.09 P value 0.54 0.29 0.05 0.03 0.99 Photoperiod 16 10.68 56.14 2.97a 3.61b 0 14 10.87 53.97 2.82b 3.82a 0.14 12 11.00 54.51 2.98a 3.71b 0.14 P value 0.42 0.46 0.02 0.02 0.11 Lighting pattern × photoperiod Continuous 16 h 10.63 56.60 3.03a 3.51c 0 Continuous 14 h 10.74 54.56 2.79b 3.87a 0.22 Continuous 12 h 11.00 55.82 3.10a 3.55c 0.07 Intermittent 16 h 10.73 55.68 2.91a,b 3.70b 0 Intermittent 14 h 11.00 53.37 2.86b 3.77b 0.07 Intermittent 12 h 11.00 53.21 2.85b 3.86a 0.21 P value 0.87 0.88 0.04 0.02 0.17 a–cValues with different letter superscripts in the same column mean significant difference (P < 0.05). AFI = average feed intake; FER = feed egg ratio. View Large Table 4 shows that the egg production during 22 to 57 wk was not significantly affected by lighting pattern alone (P > 0.05). Egg-laying rate, EM, FER, and mortality rate were not significantly affected by photoperiod alone (P > 0.05), but AFI was significantly higher in 12 h than those in 14 and 16 h groups (P = 0.01). There were no significant effects on the egg production for the combination of lighting pattern and photoperiod during 22 to 57 wk (P > 0.05). Table 4. Effects of lighting pattern and photoperiod on egg production of Beijing You Chicken during 22 to 57 wk. Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.77 57.47 2.94 3.67 0.08 Intermittent 16 10.85 55.16 2.84 3.83 0 Continuous 14 10.71 55.69 2.75 3.89 0.14 Intermittent 14 10.91 54.55 2.78 3.92 0.08 Continuous 12 11.21 51.59 2.77 4.05 0.05 Intermittent 12 11.35 54.84 2.87 3.95 0.16 SEM 0.07 0.85 0.05 0.30 0.02 GLM analysis Arcsine transformation Lighting pattern Continuous 10.90 54.92 2.82 4.70 0.09 Intermittent 11.04 54.85 2.83 4.68 0.08 P value 0.34 0.97 0.90 0.97 0.79 Photoperiod 16 10.81b 56.31 2.89 4.31 0.03 14 10.81b 55.12 2.77 4.96 0.03 12 11.29a 53.22 2.82 4.80 0.03 P value 0.01 0.33 0.55 0.66 0.23 Lighting pattern × photoperiod P value 0.94 0.38 0.69 0.96 0.08 Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.77 57.47 2.94 3.67 0.08 Intermittent 16 10.85 55.16 2.84 3.83 0 Continuous 14 10.71 55.69 2.75 3.89 0.14 Intermittent 14 10.91 54.55 2.78 3.92 0.08 Continuous 12 11.21 51.59 2.77 4.05 0.05 Intermittent 12 11.35 54.84 2.87 3.95 0.16 SEM 0.07 0.85 0.05 0.30 0.02 GLM analysis Arcsine transformation Lighting pattern Continuous 10.90 54.92 2.82 4.70 0.09 Intermittent 11.04 54.85 2.83 4.68 0.08 P value 0.34 0.97 0.90 0.97 0.79 Photoperiod 16 10.81b 56.31 2.89 4.31 0.03 14 10.81b 55.12 2.77 4.96 0.03 12 11.29a 53.22 2.82 4.80 0.03 P value 0.01 0.33 0.55 0.66 0.23 Lighting pattern × photoperiod P value 0.94 0.38 0.69 0.96 0.08 a,bValues with different letter superscripts in the same column mean significant difference (P < 0.05). AFI = average feed intake; FER = feed egg ratio. View Large Table 4. Effects of lighting pattern and photoperiod on egg production of Beijing You Chicken during 22 to 57 wk. Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.77 57.47 2.94 3.67 0.08 Intermittent 16 10.85 55.16 2.84 3.83 0 Continuous 14 10.71 55.69 2.75 3.89 0.14 Intermittent 14 10.91 54.55 2.78 3.92 0.08 Continuous 12 11.21 51.59 2.77 4.05 0.05 Intermittent 12 11.35 54.84 2.87 3.95 0.16 SEM 0.07 0.85 0.05 0.30 0.02 GLM analysis Arcsine transformation Lighting pattern Continuous 10.90 54.92 2.82 4.70 0.09 Intermittent 11.04 54.85 2.83 4.68 0.08 P value 0.34 0.97 0.90 0.97 0.79 Photoperiod 16 10.81b 56.31 2.89 4.31 0.03 14 10.81b 55.12 2.77 4.96 0.03 12 11.29a 53.22 2.82 4.80 0.03 P value 0.01 0.33 0.55 0.66 0.23 Lighting pattern × photoperiod P value 0.94 0.38 0.69 0.96 0.08 Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.77 57.47 2.94 3.67 0.08 Intermittent 16 10.85 55.16 2.84 3.83 0 Continuous 14 10.71 55.69 2.75 3.89 0.14 Intermittent 14 10.91 54.55 2.78 3.92 0.08 Continuous 12 11.21 51.59 2.77 4.05 0.05 Intermittent 12 11.35 54.84 2.87 3.95 0.16 SEM 0.07 0.85 0.05 0.30 0.02 GLM analysis Arcsine transformation Lighting pattern Continuous 10.90 54.92 2.82 4.70 0.09 Intermittent 11.04 54.85 2.83 4.68 0.08 P value 0.34 0.97 0.90 0.97 0.79 Photoperiod 16 10.81b 56.31 2.89 4.31 0.03 14 10.81b 55.12 2.77 4.96 0.03 12 11.29a 53.22 2.82 4.80 0.03 P value 0.01 0.33 0.55 0.66 0.23 Lighting pattern × photoperiod P value 0.94 0.38 0.69 0.96 0.08 a,bValues with different letter superscripts in the same column mean significant difference (P < 0.05). AFI = average feed intake; FER = feed egg ratio. View Large Table 5 shows that there were significant effects on EST, AH, HU, and EG by the lighting pattern alone (P < 0.05) at 37 wk. Eggshell thickness, AH, HU, and EG in continuous groups were significantly lower than those in intermittent groups (P = 0.01, P = 0.04, P = 0.05, and P = 0.03). Egg weight and AH were significantly affected by photoperiod alone (P < 0.05). Egg weight and AH in 12 h groups were significantly higher than those in 16 and 14 h groups (P = 0.02 and P = 0.01). There were no significant effects on the egg quality for the combination of lighting pattern and photoperiod at 37 wk (P > 0.05). Table 5. Effects of lighting pattern and photoperiod on egg quality of Beijing You Chicken at 37 wk (n = 30). Photoperiod ESS/ EST/ ESC/ AH/ RYW RESW RAW Lighting pattern /(h) EW/(g) (kg/cm2) (mm) (%) (mm) HU YC EG ESI /(%) /(%) /(%) Continuous 16 47.64 4.35 0.40 46.95 4.06 63.82 7.20 2.07 1.31 29.22 13.28 57.51 Intermittent 16 50.71 4.36 0.44 49.80 4.42 65.61 7.07 2.13 1.33 28.68 13.36 57.96 Continuous 14 50.28 4.63 0.41 49.44 3.87 60.53 7.67 1.93 1.33 30.51 13.52 55.97 Intermittent 14 49.43 4.19 0.43 46.09 4.53 67.87 6.93 2.33 1.33 29.10 13.13 57.77 Continuous 12 52.61 4.35 0.40 51.01 4.73 67.17 7.20 2.13 1.34 29.07 13.04 57.89 Intermittent 12 52.31 4.39 0.42 52.07 5.49 75.45 7.27 2.80 1.35 30.01 13.11 56.88 SEM 0.52 0.07 0.004 0.74 0.15 1.47 0.10 0.09 0.01 0.34 0.16 0.46 GLM analysis Arcsine transformation Lighting pattern Continuous 50.18 4.44 0.40b 49.13 4.22b 63.84b 7.36 2.04b 1.32 29.59 13.28 57.12 Intermittent 50.82 4.31 0.43a 49.32 4.81a 69.64a 7.08 2.42a 1.33 29.27 13.20 57.53 P value 0.52 0.34 0.01 0.89 0.04 0.05 0.21 0.03 0.51 0.69 0.80 0.78 Photoperiod (h) 16 49.17b 4.35 0.42 48.37 4.24b 64.71 7.13 2.10 1.32 28.95 13.32 57.73 14 49.85b 4.41 0.42 47.76 4.19b 64.19 7.30 2.13 1.33 29.81 13.32 56.87 12 52.46a 4.37 0.41 51.54 5.11a 71.31 7.23 2.47 1.34 29.54 13.08 57.39 P value 0.02 0.95 0.23 0.08 0.01 0.08 0.81 0.16 0.15 0.50 0.77 0.50 Lighting pattern × photoperiod P value 0.23 0.29 0.10 0.21 0.83 0.61 0.27 0.36 0.78 0.12 0.78 0.17 Photoperiod ESS/ EST/ ESC/ AH/ RYW RESW RAW Lighting pattern /(h) EW/(g) (kg/cm2) (mm) (%) (mm) HU YC EG ESI /(%) /(%) /(%) Continuous 16 47.64 4.35 0.40 46.95 4.06 63.82 7.20 2.07 1.31 29.22 13.28 57.51 Intermittent 16 50.71 4.36 0.44 49.80 4.42 65.61 7.07 2.13 1.33 28.68 13.36 57.96 Continuous 14 50.28 4.63 0.41 49.44 3.87 60.53 7.67 1.93 1.33 30.51 13.52 55.97 Intermittent 14 49.43 4.19 0.43 46.09 4.53 67.87 6.93 2.33 1.33 29.10 13.13 57.77 Continuous 12 52.61 4.35 0.40 51.01 4.73 67.17 7.20 2.13 1.34 29.07 13.04 57.89 Intermittent 12 52.31 4.39 0.42 52.07 5.49 75.45 7.27 2.80 1.35 30.01 13.11 56.88 SEM 0.52 0.07 0.004 0.74 0.15 1.47 0.10 0.09 0.01 0.34 0.16 0.46 GLM analysis Arcsine transformation Lighting pattern Continuous 50.18 4.44 0.40b 49.13 4.22b 63.84b 7.36 2.04b 1.32 29.59 13.28 57.12 Intermittent 50.82 4.31 0.43a 49.32 4.81a 69.64a 7.08 2.42a 1.33 29.27 13.20 57.53 P value 0.52 0.34 0.01 0.89 0.04 0.05 0.21 0.03 0.51 0.69 0.80 0.78 Photoperiod (h) 16 49.17b 4.35 0.42 48.37 4.24b 64.71 7.13 2.10 1.32 28.95 13.32 57.73 14 49.85b 4.41 0.42 47.76 4.19b 64.19 7.30 2.13 1.33 29.81 13.32 56.87 12 52.46a 4.37 0.41 51.54 5.11a 71.31 7.23 2.47 1.34 29.54 13.08 57.39 P value 0.02 0.95 0.23 0.08 0.01 0.08 0.81 0.16 0.15 0.50 0.77 0.50 Lighting pattern × photoperiod P value 0.23 0.29 0.10 0.21 0.83 0.61 0.27 0.36 0.78 0.12 0.78 0.17 a,bValues with different letter superscripts in the same column mean significant difference (P < 0.05). EW = egg weight; ESS = eggshell strength; EST = eggshell thickness; ESC = eggshell color; AH = albumen height; HU = Haugh unit; YC = yolk color; EG = egg grade; ESI = egg shape index; RYW = relative yolk weight; RESW = relative eggshell weight; RAW = relative albumen weight. View Large Table 5. Effects of lighting pattern and photoperiod on egg quality of Beijing You Chicken at 37 wk (n = 30). Photoperiod ESS/ EST/ ESC/ AH/ RYW RESW RAW Lighting pattern /(h) EW/(g) (kg/cm2) (mm) (%) (mm) HU YC EG ESI /(%) /(%) /(%) Continuous 16 47.64 4.35 0.40 46.95 4.06 63.82 7.20 2.07 1.31 29.22 13.28 57.51 Intermittent 16 50.71 4.36 0.44 49.80 4.42 65.61 7.07 2.13 1.33 28.68 13.36 57.96 Continuous 14 50.28 4.63 0.41 49.44 3.87 60.53 7.67 1.93 1.33 30.51 13.52 55.97 Intermittent 14 49.43 4.19 0.43 46.09 4.53 67.87 6.93 2.33 1.33 29.10 13.13 57.77 Continuous 12 52.61 4.35 0.40 51.01 4.73 67.17 7.20 2.13 1.34 29.07 13.04 57.89 Intermittent 12 52.31 4.39 0.42 52.07 5.49 75.45 7.27 2.80 1.35 30.01 13.11 56.88 SEM 0.52 0.07 0.004 0.74 0.15 1.47 0.10 0.09 0.01 0.34 0.16 0.46 GLM analysis Arcsine transformation Lighting pattern Continuous 50.18 4.44 0.40b 49.13 4.22b 63.84b 7.36 2.04b 1.32 29.59 13.28 57.12 Intermittent 50.82 4.31 0.43a 49.32 4.81a 69.64a 7.08 2.42a 1.33 29.27 13.20 57.53 P value 0.52 0.34 0.01 0.89 0.04 0.05 0.21 0.03 0.51 0.69 0.80 0.78 Photoperiod (h) 16 49.17b 4.35 0.42 48.37 4.24b 64.71 7.13 2.10 1.32 28.95 13.32 57.73 14 49.85b 4.41 0.42 47.76 4.19b 64.19 7.30 2.13 1.33 29.81 13.32 56.87 12 52.46a 4.37 0.41 51.54 5.11a 71.31 7.23 2.47 1.34 29.54 13.08 57.39 P value 0.02 0.95 0.23 0.08 0.01 0.08 0.81 0.16 0.15 0.50 0.77 0.50 Lighting pattern × photoperiod P value 0.23 0.29 0.10 0.21 0.83 0.61 0.27 0.36 0.78 0.12 0.78 0.17 Photoperiod ESS/ EST/ ESC/ AH/ RYW RESW RAW Lighting pattern /(h) EW/(g) (kg/cm2) (mm) (%) (mm) HU YC EG ESI /(%) /(%) /(%) Continuous 16 47.64 4.35 0.40 46.95 4.06 63.82 7.20 2.07 1.31 29.22 13.28 57.51 Intermittent 16 50.71 4.36 0.44 49.80 4.42 65.61 7.07 2.13 1.33 28.68 13.36 57.96 Continuous 14 50.28 4.63 0.41 49.44 3.87 60.53 7.67 1.93 1.33 30.51 13.52 55.97 Intermittent 14 49.43 4.19 0.43 46.09 4.53 67.87 6.93 2.33 1.33 29.10 13.13 57.77 Continuous 12 52.61 4.35 0.40 51.01 4.73 67.17 7.20 2.13 1.34 29.07 13.04 57.89 Intermittent 12 52.31 4.39 0.42 52.07 5.49 75.45 7.27 2.80 1.35 30.01 13.11 56.88 SEM 0.52 0.07 0.004 0.74 0.15 1.47 0.10 0.09 0.01 0.34 0.16 0.46 GLM analysis Arcsine transformation Lighting pattern Continuous 50.18 4.44 0.40b 49.13 4.22b 63.84b 7.36 2.04b 1.32 29.59 13.28 57.12 Intermittent 50.82 4.31 0.43a 49.32 4.81a 69.64a 7.08 2.42a 1.33 29.27 13.20 57.53 P value 0.52 0.34 0.01 0.89 0.04 0.05 0.21 0.03 0.51 0.69 0.80 0.78 Photoperiod (h) 16 49.17b 4.35 0.42 48.37 4.24b 64.71 7.13 2.10 1.32 28.95 13.32 57.73 14 49.85b 4.41 0.42 47.76 4.19b 64.19 7.30 2.13 1.33 29.81 13.32 56.87 12 52.46a 4.37 0.41 51.54 5.11a 71.31 7.23 2.47 1.34 29.54 13.08 57.39 P value 0.02 0.95 0.23 0.08 0.01 0.08 0.81 0.16 0.15 0.50 0.77 0.50 Lighting pattern × photoperiod P value 0.23 0.29 0.10 0.21 0.83 0.61 0.27 0.36 0.78 0.12 0.78 0.17 a,bValues with different letter superscripts in the same column mean significant difference (P < 0.05). EW = egg weight; ESS = eggshell strength; EST = eggshell thickness; ESC = eggshell color; AH = albumen height; HU = Haugh unit; YC = yolk color; EG = egg grade; ESI = egg shape index; RYW = relative yolk weight; RESW = relative eggshell weight; RAW = relative albumen weight. View Large Table 6 shows that there were no significant effects on most of egg quality parameters by lighting pattern, photoperiod alone, and in combination at 57 wk (P > 0.05), except for RAW. Relative albumen weight in 12 h groups was significantly lower than those in 16 and 14 h groups (P = 0.02). Egg weight and AH in 12 h groups were higher than those in 16 and 14 h groups, close to the significant level (P = 0.07 and P = 0.09). Table 6. Effects of lighting pattern and photoperiod on egg quality of BYC at 57 wk (n = 30). Photoperiod ESS/ EST/ ESC/ AH/ RYW/ RESW/ RAW/ Lighting pattern /(h) EW/(g) (kg/cm2) (mm) (%) (mm) HU YC EG ESI (%) (%) (%) Continuous 16 52.35 3.34 0.40 44.23 4.10 61.09 6.13 1.87 1.38 31.46 12.86 61.12 Intermittent 16 54.79 3.49 0.40 49.83 4.59 63.80 6.13 1.93 1.37 31.03 12.51 57.03 Continuous 14 54.83 3.35 0.40 45.94 3.96 60.71 6.00 1.60 1.59 31.18 12.57 57.31 Intermittent 14 52.41 3.07 0.39 47.80 4.33 64.48 6.00 2.07 1.38 32.07 12.56 61.76 Continuous 12 55.32 3.36 0.40 48.95 4.98 69.73 5.60 2.33 1.35 30.75 12.68 55.85 Intermittent 12 56.93 3.40 0.39 48.95 4.94 67.22 6.13 2.07 1.39 30.40 12.24 53.84 SEM 0.53 0.07 0.002 0.74 0.16 1.54 0.11 0.09 0.04 0.26 0.13 0.84 GLM analysis Arcsine transformation Lighting pattern Continuous 54.17 3.35 0.39 46.38 4.35 63.84 5.91 1.93 1.44 31.13 12.71 58.09 Intermittent 54.71 3.32 0.39 48.86 4.62 65.17 6.09 2.02 1.38 31.17 12.44 57.54 P value 0.60 0.85 0.18 0.09 0.38 0.67 0.43 0.64 0.46 0.41 0.31 0.74 Photoperiod (h) 16 53.57 3.42 0.40 47.03 4.35 62.45 6.13 1.90 1.38 31.25 12.68 59.08a 14 53.62 3.21 0.39 46.87 4.14 62.59 6.00 1.83 1.48 31.62 12.57 59.54a 12 56.13 3.38 0.40 48.95 4.96 68.48 5.87 2.00 1.37 30.58 12.46 54.84b P value 0.07 0.48 0.74 0.44 0.09 0.19 0.62 0.25 0.43 0.12 0.79 0.02 Lighting pattern × Photoperiod P value 0.13 0.46 0.26 0.29 0.76 0.68 0.53 0.29 0.44 0.60 0.78 0.23 Photoperiod ESS/ EST/ ESC/ AH/ RYW/ RESW/ RAW/ Lighting pattern /(h) EW/(g) (kg/cm2) (mm) (%) (mm) HU YC EG ESI (%) (%) (%) Continuous 16 52.35 3.34 0.40 44.23 4.10 61.09 6.13 1.87 1.38 31.46 12.86 61.12 Intermittent 16 54.79 3.49 0.40 49.83 4.59 63.80 6.13 1.93 1.37 31.03 12.51 57.03 Continuous 14 54.83 3.35 0.40 45.94 3.96 60.71 6.00 1.60 1.59 31.18 12.57 57.31 Intermittent 14 52.41 3.07 0.39 47.80 4.33 64.48 6.00 2.07 1.38 32.07 12.56 61.76 Continuous 12 55.32 3.36 0.40 48.95 4.98 69.73 5.60 2.33 1.35 30.75 12.68 55.85 Intermittent 12 56.93 3.40 0.39 48.95 4.94 67.22 6.13 2.07 1.39 30.40 12.24 53.84 SEM 0.53 0.07 0.002 0.74 0.16 1.54 0.11 0.09 0.04 0.26 0.13 0.84 GLM analysis Arcsine transformation Lighting pattern Continuous 54.17 3.35 0.39 46.38 4.35 63.84 5.91 1.93 1.44 31.13 12.71 58.09 Intermittent 54.71 3.32 0.39 48.86 4.62 65.17 6.09 2.02 1.38 31.17 12.44 57.54 P value 0.60 0.85 0.18 0.09 0.38 0.67 0.43 0.64 0.46 0.41 0.31 0.74 Photoperiod (h) 16 53.57 3.42 0.40 47.03 4.35 62.45 6.13 1.90 1.38 31.25 12.68 59.08a 14 53.62 3.21 0.39 46.87 4.14 62.59 6.00 1.83 1.48 31.62 12.57 59.54a 12 56.13 3.38 0.40 48.95 4.96 68.48 5.87 2.00 1.37 30.58 12.46 54.84b P value 0.07 0.48 0.74 0.44 0.09 0.19 0.62 0.25 0.43 0.12 0.79 0.02 Lighting pattern × Photoperiod P value 0.13 0.46 0.26 0.29 0.76 0.68 0.53 0.29 0.44 0.60 0.78 0.23 a,bValues with different letter superscripts in the same column mean significant difference (P < 0.05). EW = egg weight; ESS = eggshell strength; EST = eggshell thickness; ESC = eggshell color; AH = albumen height; HU = Haugh unit; YC = yolk color; EG = egg grade; ESI = egg shape index; RYW = relative yolk weight; RESW = relative eggshell weight; RAW = relative albumen weight. View Large Table 6. Effects of lighting pattern and photoperiod on egg quality of BYC at 57 wk (n = 30). Photoperiod ESS/ EST/ ESC/ AH/ RYW/ RESW/ RAW/ Lighting pattern /(h) EW/(g) (kg/cm2) (mm) (%) (mm) HU YC EG ESI (%) (%) (%) Continuous 16 52.35 3.34 0.40 44.23 4.10 61.09 6.13 1.87 1.38 31.46 12.86 61.12 Intermittent 16 54.79 3.49 0.40 49.83 4.59 63.80 6.13 1.93 1.37 31.03 12.51 57.03 Continuous 14 54.83 3.35 0.40 45.94 3.96 60.71 6.00 1.60 1.59 31.18 12.57 57.31 Intermittent 14 52.41 3.07 0.39 47.80 4.33 64.48 6.00 2.07 1.38 32.07 12.56 61.76 Continuous 12 55.32 3.36 0.40 48.95 4.98 69.73 5.60 2.33 1.35 30.75 12.68 55.85 Intermittent 12 56.93 3.40 0.39 48.95 4.94 67.22 6.13 2.07 1.39 30.40 12.24 53.84 SEM 0.53 0.07 0.002 0.74 0.16 1.54 0.11 0.09 0.04 0.26 0.13 0.84 GLM analysis Arcsine transformation Lighting pattern Continuous 54.17 3.35 0.39 46.38 4.35 63.84 5.91 1.93 1.44 31.13 12.71 58.09 Intermittent 54.71 3.32 0.39 48.86 4.62 65.17 6.09 2.02 1.38 31.17 12.44 57.54 P value 0.60 0.85 0.18 0.09 0.38 0.67 0.43 0.64 0.46 0.41 0.31 0.74 Photoperiod (h) 16 53.57 3.42 0.40 47.03 4.35 62.45 6.13 1.90 1.38 31.25 12.68 59.08a 14 53.62 3.21 0.39 46.87 4.14 62.59 6.00 1.83 1.48 31.62 12.57 59.54a 12 56.13 3.38 0.40 48.95 4.96 68.48 5.87 2.00 1.37 30.58 12.46 54.84b P value 0.07 0.48 0.74 0.44 0.09 0.19 0.62 0.25 0.43 0.12 0.79 0.02 Lighting pattern × Photoperiod P value 0.13 0.46 0.26 0.29 0.76 0.68 0.53 0.29 0.44 0.60 0.78 0.23 Photoperiod ESS/ EST/ ESC/ AH/ RYW/ RESW/ RAW/ Lighting pattern /(h) EW/(g) (kg/cm2) (mm) (%) (mm) HU YC EG ESI (%) (%) (%) Continuous 16 52.35 3.34 0.40 44.23 4.10 61.09 6.13 1.87 1.38 31.46 12.86 61.12 Intermittent 16 54.79 3.49 0.40 49.83 4.59 63.80 6.13 1.93 1.37 31.03 12.51 57.03 Continuous 14 54.83 3.35 0.40 45.94 3.96 60.71 6.00 1.60 1.59 31.18 12.57 57.31 Intermittent 14 52.41 3.07 0.39 47.80 4.33 64.48 6.00 2.07 1.38 32.07 12.56 61.76 Continuous 12 55.32 3.36 0.40 48.95 4.98 69.73 5.60 2.33 1.35 30.75 12.68 55.85 Intermittent 12 56.93 3.40 0.39 48.95 4.94 67.22 6.13 2.07 1.39 30.40 12.24 53.84 SEM 0.53 0.07 0.002 0.74 0.16 1.54 0.11 0.09 0.04 0.26 0.13 0.84 GLM analysis Arcsine transformation Lighting pattern Continuous 54.17 3.35 0.39 46.38 4.35 63.84 5.91 1.93 1.44 31.13 12.71 58.09 Intermittent 54.71 3.32 0.39 48.86 4.62 65.17 6.09 2.02 1.38 31.17 12.44 57.54 P value 0.60 0.85 0.18 0.09 0.38 0.67 0.43 0.64 0.46 0.41 0.31 0.74 Photoperiod (h) 16 53.57 3.42 0.40 47.03 4.35 62.45 6.13 1.90 1.38 31.25 12.68 59.08a 14 53.62 3.21 0.39 46.87 4.14 62.59 6.00 1.83 1.48 31.62 12.57 59.54a 12 56.13 3.38 0.40 48.95 4.96 68.48 5.87 2.00 1.37 30.58 12.46 54.84b P value 0.07 0.48 0.74 0.44 0.09 0.19 0.62 0.25 0.43 0.12 0.79 0.02 Lighting pattern × Photoperiod P value 0.13 0.46 0.26 0.29 0.76 0.68 0.53 0.29 0.44 0.60 0.78 0.23 a,bValues with different letter superscripts in the same column mean significant difference (P < 0.05). EW = egg weight; ESS = eggshell strength; EST = eggshell thickness; ESC = eggshell color; AH = albumen height; HU = Haugh unit; YC = yolk color; EG = egg grade; ESI = egg shape index; RYW = relative yolk weight; RESW = relative eggshell weight; RAW = relative albumen weight. View Large DISCUSSION Lighting had important effects on growth and development, performance, and healthy condition in poultry (Zhang 2008). There has been a lot of research about the effects of intermittent lighting on performance of birds (Rowland 1985), but mostly concentrating on commercial high-producing poultry, not on traditional or native chicken. Freitas et al. (2005) compared a kind of intermittent lighting, natural gradual increasing light, and a kind of continuous lighting, and found that the intermittent lighting and natural gradual increasing lighting did not affect the egg production of the layers in open house. Leeson et al. (2005) compared the effects of various step-down lighting regimens in the rearing period on rearing and laying performance in commercial laying pullets, and found that step-down lighting had no significant improvement in egg numbers, egg mass, etc. Gewehr and Freitas (2007) showed that intermittent lighting did not affect the performance and could be an alternative way of lighting for the layers. Effects of photoperiod on birds mainly reflect in establishment of circadian rhythm (Dawson et al., 2001) and regulation of prolactin concentration (Johnston 2004). In this present study, 2 lighting patterns (continuous and intermittent lighting) and 3 photoperiods (16, 14, 12 h) were arranged to study the effects of lighting pattern, photoperiod alone, and in combination on egg production of BYC, and found that egg-laying rate, EM, and FER during 22 to 43 and 22 to 57 wk were not significantly affected by lighting pattern alone (P > 0.05), which supported the above that intermittent lighting did not affect the egg production of laying hens, but AFI in 12 h groups was significantly higher than those in 14 and 16 h groups (P < 0.05). Ma et al. (2011) studied the effects of photoperiod on feeding duration and feed intake of BYC, and found that the shorter the photoperiod, the longer the feeding duration and feed intake of the birds, whereas Lewis et al. (2007) reported that the feed intake in the laying period was not significantly affected by the rearing photoperiod for Lohmann Brown. The higher AFI here may be due to the birds having the capability of perceiving day-length and adjusting feed intake, which needs further research. Egg mass and FER are important indicators of egg production. During 44 to 57 wk, EM was significantly higher (2.97 > 2.87, P = 0.05) and FER was significantly lower (3.64 < 3.78, P = 0.03) in continuous groups than in intermittent groups, which suggested that continuous lighting was better for the egg production in late laying period of the bird. The mortality rate of the birds during 22 to 43, 44 to 57, and 22 to 57 wk were not significantly affected by the lighting pattern, photoperiod alone, and in combination, which was partly in agreement with Lewis et al. (2007) who reported that mortality of the layers during laying phases was unaffected by the photoperiod, whereas properly designed intermittent lighting (8L:6D:2L:8D) could reduce mortality of Japanese quail (Zahoor et al., 2011). Photoperiod affected the egg weight, yolk ratio, and eggshell thickness (Lewis and Morris 2006), and also the sexual maturation of the layers (Chen et al., 2007). Pan et al. (2007) reported that both light increasing ways and photoperiod affected the egg quality of Hy-Line Brown layers, and this effect may be through affecting the oviduct shape and further influencing on egg quality (Wang et al., 2009). Shen et al. (2012) compared two continuous lighting and two intermittent lighting on egg quality of BYC at 28, 38, and 48 wk of age, and found that the EW and RYW were 1.63% and 8.91% higher in intermittent 12 h group than in continuous 16 h group, respectively. In this study there were no significant effects on most of egg quality parameters by lighting pattern, photoperiod alone, and in combination at 57 wk (P > 0.05), but RAW in 12 h groups was significantly lower than those in 16 and 14 h groups (P = 0.02). Zhang et al. (2009) compared the egg quality between BYC and Lohmann Pink when their egg-laying rate reached 50%, and found that there were significant differences in most of parameters including EW, ESC, ESS, EST, AH, HU, YC, etc., except RESW, which indicated that the breed is an important factor affecting egg quality. Here this present study indicated that there had significant effects on EST, AH, HU, and EG by the lighting pattern alone (P < 0.05) at 37 wk of age. Eggshell thickness, AH, HU, and EG in continuous lighting groups were significantly lower than those in intermittent lighting groups (P < 0.05). Albumen height and HU are important parameters reflecting the egg freshness and albumen quality, eggshell thickness is related with the shelf life of eggs, egg grade reflects the freshness of eggs, so higher EST, AH, HU and EG in intermittent lighting groups indicates better egg quality, which may be related to less egg production during 44 to 57 wk. Jácome et al. (2014) studied that commercial layers in Brazil are photo-stimulated with more than 12 h of light, and suggested the lighting programs influenced egg production, but not egg quality indices. In this study, EW in 12 h groups was significantly higher than those in 16 and 14 h groups (P < 0.05), considering higher AFI in 12 h groups above, we suggest 12 h lighting is enough for meeting the requirement of egg production and egg quality of the native chicken. We previously used 6 photoperiodic treatments to study the egg laying of BYC during 20 to 61 wk (Geng et al. 2014), including 16L:8D (0600 to 2200 h), 12L:2D:4L:6D, 8L:4D:4L:8D, 16L:8D (0300 to 1900 h),14L:10D, and 18L:6D, and found that average egg-laying rate of 12L:2D:4L:6D group (62.91%) and 14L:10D (61.74%) were significantly higher than others except 8L:4D:4L:8D group (61.13%), though no change in photoperiod from the rearing to production phase for this group (12 to 12 L). In this present study, we had the same 12 L schedule for groups 5 and 6 (12L:12D and 8L:4D:4L:8D, respectively), and found that 12 L significantly improved the AFI of chicken during 22 to 57 wk, EM during 44 to 57 wk, and decreased RAW at 57 wk, suggesting that no change in photoperiod from rearing to the production phase will have long-lasting effects on egg production or egg quality, the related mechanism needs further research. CONCLUSION The present study indicated that 1) the egg production was not significantly affected by lighting pattern alone during 22 to 57 wk (P > 0.05), but the photoperiod significantly affected AFI (P < 0.05); 2) continuous lighting is better for the egg production during 44 to 57 wk, and intermittent lighting is better for egg quality of the native bird at 37 wk; 3) 12 h lighting is enough for meeting the requirement of the native chicken during the laying period; 4) no change in photoperiod from the rearing to the production phase (12 to 12 L) will have long-lasting effects on egg production or egg quality under the present condition. Acknowledgements The authors wish to thank National Natural Science Funds (grant numbers 31372353, 30972128), Beijing Natural Science Fund (grant number 6102010) for providing financial supports, and staff from BYC Breeder Farm for feeding and management of the experimental birds. REFERENCES Chen H. , Huang R. L. , Zhang H. X. , Di K. Q. , Pan D. , Hou Y. G. . 2007 . Effects of photoperiod on ovarian morphology and carcass traits at sexual maturity in pullets . Poult. Sci. 86 : 917 – 920 . Google Scholar CrossRef Search ADS PubMed Dawson A. , King V. M. , Bentley G. E. , Ball G. F. . 2001 . Photoperiodic control of seasonality in birds . J. Biol. Rhythms 16 : 365 – 380 . Google Scholar CrossRef Search ADS PubMed Freitas H. J. , Cott J. T. B. , Oliveira A. I. , Gewehr C. E. . 2005 . Avaliação de programas de iluminação sobre o desempenho zootécnico de poedeiras leves . Ciênc. Agrotec. 29 : 424 – 428 . Google Scholar CrossRef Search ADS Geng A. L. , Xu S. F. , Zhang Y. , Zhang J. , Chu Q. , Liu H. G. . 2014 . Effects of photoperiod on broodiness, egg-laying and endocrine responses in native laying hens . Br. Poult. Sci. 55 : 264 – 269 . Google Scholar CrossRef Search ADS PubMed Geweher C. E. , Freitas H. G. . 2007 . Iluminação intermitente para poedeiras criadas em galpões abertos . Rev. Ciênc. Agroveter. 6 : 54 – 62 . Hocking P. M. , Bain M. , Channing C. E. , Fleming R. , Wilson S. . 2003 . Genetic variation for egg production, egg quality and bone strength in selected and traditional breeds of laying fowl . Br. Poult. Sci. 44 : 365 – 373 . Google Scholar CrossRef Search ADS PubMed Jacome I. , Rossi L. , Borille R. . 2014 . Influence of artificial lighting on the performance and egg quality of commercial layers: a review . Rev. Bras. Cienc. Avic. 16 : 337 – 344 . Google Scholar CrossRef Search ADS Johnston J. D. 2004 . Photoperiodic regulation of prolactin secretion: changes in intra-pituitary signaling and lactotroph heterogeneity . J. Endocrino. 3 : 351 – 356 . Google Scholar CrossRef Search ADS Juliet R. R. 2004 . Factors affecting egg internal quality and egg shell quality in laying hens . Jpn. Poult. Sci. 41 : 161 – 177 . Google Scholar CrossRef Search ADS Koelkebeck K. W. 1999 . What is egg quality and conserving it . [cited 1999 June] . http://livestocktrail.illinois.edu/poultrynet/paperDisplay.cfm?ContentID=522. accessed on March 29, 2018 . Leeson S. , Caston L. , Lewis P. D. . 2005 . Rearing and laying performance following various step-down lighting regimens in the rearing period . Poult. Sci. 84 : 626 – 632 . Google Scholar CrossRef Search ADS PubMed Lewis P. D. , Morris T. R. . 2006 . 28 – 30 Poultry Lighting: The Theory and Practice . Nottingham University Press, North Carolina. Lewis P. D. , Caston L. , Leeson S. . 2007 . Rearing photoperiod and abrupt versus gradual photostimulation for egg-type pullets . Br. Poult. Sci. 48 : 276 – 283 . Google Scholar CrossRef Search ADS PubMed Liu H. G. , Xu S. F. . 2001 . Beijing Fatty Chicken and their development and utilization . Eco. Domest. Anim. 22 : 50 – 52 . Ma H. , Li B. M. , Shen L. , Geng A. L. , Zhang Y. , Shi Z. X. . 2001 . Effects of lighting on feeding regulation of Beijing You Chicken during laying period . Proc. 5th China Anim. Sci. Tech. Forum. Chongqing, Rongchang . National Livestock and Poultry Genetic Resources Committee. Animal Genetic Resources in China. Poultry . 2011 . China Agriculture Publishing House , Beijing . Pan D. , Chen H. , Di K. Q. , Guo Y. X. , Zhang Z. J. , Huang R. L. . 2007 . Effects of photoperiod on egg quality of layer during the peak laying period . Heilongjiang Anim. Hus. Vet. Med. 7 : 59 – 60 . Rowland K. W. 1985 . Intermittent Lighting for Laying Fowls: a Review . Worlds Poult. Sci. J. 41 : 5 – 19 . Google Scholar CrossRef Search ADS Shen L. , Ma H. , Geng A. L. , Zhang Y. , Shi Z. X. . 2011 . Effect of Segmental photoperiod regime on production performance of egg-type Beijing You Chicken . China Poult. 33 : 10 – 14 . Shen L. , Geng A. L. , Ma H. , Li B. M. , Tao S. J. , Shi Z. X. . 2012 . Effect of photoperiod programs on egg quality of egg-type Beijing You Chickens . China Poult. 34 : 23 – 26 . Tang S. , Li D. L. , Jia Y. X. , Liu Z. Z. , Zheng M. Q. , Qin N. , Bai H. , Zhu J. , Bi Y. L. , Liu N. , Hua D. K. , Chen Y. , Zhao G. P. , Wen J. , Chen J. L. . 2012 . Effects of lighting rhythm and dietary energy and protein level on comprehensive performance of middle speed yellow feather broilers . China Poult. 34 : 61 – 62 . Wang C. J. , Chen H. , Hou Y. G. , Wang F. , Wang H. F. , Huang R. L. . 2009 . Comparative morphological study on oviduct and egg quality in different photoperiod . J. Agr. Univ. Hebei. 32 : 88 – 91 . Zhang S. H. 2008 . Research on feather pecking development of chicks under different environment . Northeast Agri. Univ. PhD Diss., Harbin . Zhang J. , Chu Q. , Liu H. G. . 2009 . Study of egg quality of different breeds at earlier stage of laying . Proc. 14th National Poult. Sci. Symposium . Harbin . 444 – 447 . Zahoor A. , Mian A. A. , Ahmad T. , Nadeem S. , Rrhman A. , Akram M. . 2011 . Effect of intermittent lighting on different production traits of Japanese quail. SAADC 2011 . 626 – 630 in Strategies and Challenges for Sustainable Animal Agriculture-Crop Systems, Volume III : full papers. Proc. 3rd International Conference on Sustainable Animal Agriculture for Developing Countries . Nakhon Ratchasima , Thailand . © 2018 Poultry Science Association Inc. This article is published and distributed under the term of oxford University Press, standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Poultry Science Oxford University Press

Effects of lighting pattern and photoperiod on egg production and egg quality of a native chicken under free-range condition

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Oxford University Press
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© 2018 Poultry Science Association Inc.
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0032-5791
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1525-3171
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10.3382/ps/pey104
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Abstract

ABSTRACT The paper aimed to study the effects of lighting pattern and photoperiod alone and in combination on egg production, egg quality in Beijing You Chicken (BYC). A total of 630 19-wk-old BYC laying hens were randomly allocated to 6 groups with 105 birds each, 3 replicates per group, reared in individually lit floor pens with separate outdoor areas. A 2 × 3 factorial experiment (2 lighting patterns: continuous and intermittent lighting; 3 photoperiods: 16, 14, 12 h) was arranged, including 16L:8D (6:00 to 22:00) for group 1; 12L:2D:4L:6D (6:00 to 18:00, 20:00 to 24:00) for group 2; 14L:10D (6:00 to 20:00) for group 3; 10L:2D:4L:8D (6:00 to 16:00, 18:00 to 22:00) for group 4; 12L:12D (6:00 to 18:00) for group 5, and 8L:4D:4L:8D (6:00 to 14:00, 18:00 to 22:00) for group 6, respectively. Egg production parameters were calculated for 22 to 43, 44 to 57, and 22 to 57 wk, and egg quality parameters were measured at the end of 37 and 57 wk. The results showed that the egg production of BYC was not significantly affected by lighting pattern, photoperiod alone, or in combination during 22 to 43 and 22 to 57 wk (P > 0.05), but average feed intake in 12 h groups was significantly higher than those in 14 and 16 h groups during 22 to 43 and 22 to 57 wk (P < 0.05). Egg mass and feed egg ratio were significantly affected by lighting pattern, photoperiod alone, and in combination during 44 to 57 wk (P < 0.05). Egg mass was significantly higher (P = 0.05) and feed egg ratio was significantly lower (P = 0.03) in continuous groups than in intermittent groups. There were significant effects for eggshell thickness, albumen height, haugh unit, and egg grade by lighting pattern alone (P < 0.05) at 37 wk. The study suggested that 1) the egg production was not significantly affected by lighting pattern alone during 22 to 57 wk (P > 0.05), but the photoperiod significantly affected average feed intake (P < 0.05); 2) continuous lighting is better for the egg production during 44 to 57 wk, and intermittent lighting is better for egg quality of the native bird at 37 wk; 3) 12 h lighting is enough for meeting the requirement of the native chicken during the laying period; (4) no change in photoperiod from the rearing to the production phase (12 to 12 L) will have long-lasting effects on egg production or egg quality under the present condition. INTRODUCTION In recent years, people have paid more attention to the egg quality, which is related to various external and internal qualities that are measured in eggs (Koelkebeck 1999). Egg quality is important to the egg industry worldwide. Factors affecting egg quality include strain, age, nutritional factors, stress, production system, etc. (Juliet 2004). There are clear differences in eggshell quality between modern commercial birds and traditional laying fowl (Hocking et al., 2003), and external quality such as egg shape, egg weight, etc. (Zhang et al., 2009). Beijing You Chicken (BYC), a dual-purpose native chicken used for meat and egg production in Beijing district, is well known for its characteristic appearance (having crest, beard, shank feathers, and 5-toes) and high quality of meat and egg (Liu and Xu 2001) was listed as one of the most important chicken breeds by Ministry of Agriculture, China (National Livestock and Poultry Genetic Resources Committee 2017). A lot of companies and farms emerged that are especially engaged in rearing BYC and most farms are adapted to the free range system by using the orchard, hillside, and woods where the birds go outside for food and activities at daytime, and go back into the house to rest at night. Usually the male chicken will be sold out as meat-type chicken during 90 to 120 d, and the female will be reared as egg-laying hens. Compared with modern high-producing strains such as Hy-Line Brown, Lohmann Brown, etc., BYC has a lower egg output (150 to 170 eggs per year) but still are reared under a similar lighting schedule, e.g., continuous 16 h lighting during the egg-laying period. Shen et al. (2011) studied the effects of 4 kinds of lighting treatments (16L:8D,6:00 to 22:00; 12L:2D:4L:6D, 6:00 to 18:00, 20:00 to 24:00; 8L:4D:4L:8D, 8:00 to 16:00, 20:00 to 24:00; 16L:8D, 3:00 to 19:00) on the performance of BYC laying hens, and found that the intermittent 12 h lighting (8L:4D:4L:8D) had beneficial effects on the performance for the pre-laying and peak laying period. Tang et al. (2012) compared the effects of different lighting program on the performance of growing BYC (8 to 90 d of age), and found that the weight gain of the bird in continuous 16 h group (16L:8D) was better than in intermittent 18 h group (3L:1D). Our group adopted 6 kinds of photoperiodic treatments to study the egg laying of BYC during 20 to 61wk, and found that the egg-laying rate was significantly higher in intermittent 16 h group than in continuous 16 h group (Geng et al., 2014). Based on above, the present study aimed to study the effects of lighting pattern and photoperiod alone and in combination on egg production, egg quality of BYC under free-range condition, and provide some references for the appropriate lighting management of the bird. MATERIALS AND METHODS Experimental Design and Birds The experiment was conducted at BYC Breeding Farm, Daxing district, Beijing. Six hundred and thirty 19-wk-old commercial BYC laying hens having the same genetic origin were moved from the rearing room (keeping natural photoperiod 11 to 12 h) and randomly allocated to 6 experimental groups, 105 birds every group with 3 replicates, 35 birds per replicate (pen) under free-range condition. The birds were reared in individually lit floor pens with separate outdoor areas. The indoor density was about 6.8 birds/m2, and outdoor density was about 1.9 birds/m2. Nest boxes, perches, and rice husk litters were equipped in each pen. A 2 × 3 factorial experiment was arranged (2 lighting patterns: continuous and intermittent lighting; 3 photoperiods: 16, 14, 12 h), including 16L:8D (6:00 to 22:00) for group 1; 12L:2D:4L:6D (6:00 to 18:00. 20:00 to 24:00) for group 2; 14L:10D (6:00 to 20:00) for group 3; 10L:2D:4L:8D (6:00 to 16:00,18:00 to 22:00) for group 4; 12L:12D (6:00 to 18:00) for group 5; and 8L:4D:4L:8D (6:00 to 14:00,18:00 to 22:00) for group 6, respectively (see Table 1). In order to keep the same ranging time for the birds, the groups adopted the arrangement below: lights at 6:00 in the morning every day, birds fed 6:00 to 8:00, birds range freely 8:00 to 14:00, and return to their pens at 14:00 when the second feeding time begins. Special light-proof cloth and the light controller were used in each pen. Table 1. Experimental design and lighting treatments. Group Lighting pattern Photoperiod/(h) Lighting regimen 1 Continuous 16 16L:8D (6:00 to 22:00) 2 Intermittent 16 12L:2D:4L:6D (6:00 to 18:00, 20:00 to 24:00) 3 Continuous 14 14L:10D (6:00 to 20:00) 4 Intermittent 14 10L:2D:4L:8D (6:00 to 16:00, 18:00 to 22:00) 5 Continuous 12 12L:12D (6:00 to 18:00) 6 Intermittent 12 8L:4D:4L:8D (6:00 to 14:00, 18:00 to 22:00) Group Lighting pattern Photoperiod/(h) Lighting regimen 1 Continuous 16 16L:8D (6:00 to 22:00) 2 Intermittent 16 12L:2D:4L:6D (6:00 to 18:00, 20:00 to 24:00) 3 Continuous 14 14L:10D (6:00 to 20:00) 4 Intermittent 14 10L:2D:4L:8D (6:00 to 16:00, 18:00 to 22:00) 5 Continuous 12 12L:12D (6:00 to 18:00) 6 Intermittent 12 8L:4D:4L:8D (6:00 to 14:00, 18:00 to 22:00) View Large Table 1. Experimental design and lighting treatments. Group Lighting pattern Photoperiod/(h) Lighting regimen 1 Continuous 16 16L:8D (6:00 to 22:00) 2 Intermittent 16 12L:2D:4L:6D (6:00 to 18:00, 20:00 to 24:00) 3 Continuous 14 14L:10D (6:00 to 20:00) 4 Intermittent 14 10L:2D:4L:8D (6:00 to 16:00, 18:00 to 22:00) 5 Continuous 12 12L:12D (6:00 to 18:00) 6 Intermittent 12 8L:4D:4L:8D (6:00 to 14:00, 18:00 to 22:00) Group Lighting pattern Photoperiod/(h) Lighting regimen 1 Continuous 16 16L:8D (6:00 to 22:00) 2 Intermittent 16 12L:2D:4L:6D (6:00 to 18:00, 20:00 to 24:00) 3 Continuous 14 14L:10D (6:00 to 20:00) 4 Intermittent 14 10L:2D:4L:8D (6:00 to 16:00, 18:00 to 22:00) 5 Continuous 12 12L:12D (6:00 to 18:00) 6 Intermittent 12 8L:4D:4L:8D (6:00 to 14:00, 18:00 to 22:00) View Large The birds were fed commercial corn-soybean-based diets with 15.1% crude protein (CP), 11.20 MJ/kg metabolizable energy (ME), and 2.0% calcium during 19 to 21 wk, and with 15.5% CP, 11.08 MJ/kg ME, and 2.75% calcium during 22 to 57 wk. The incandescent lamps were used, and the bulbs were 2 m off the ground, and average light intensity was 10 lux. Appropriate temperature and moisture were manipulated. Under severe weather conditions such as thundering and haze days, the birds were confined inside the pen to reduce the stress. The study was performed in accordance with local ethical guidelines and met the requirement of the institutional animal care and use committee. Measurement and Methods Feed intake, egg numbers, and egg weight of each pen were recorded every day, and weekly average feed intake (AFI), egg-laying rate, egg mass (EM), feed egg ratio (FER), and mortality rate for each group were calculated for 22 to 43, 44 to 57, and 22 to 57 wk, and egg quality parameters at the end of 37 and 57 wk were measured and calculated, respectively. A total of 10 fresh eggs were randomly chosen from each replicate, totaled 30 eggs for each group. Egg weight (EW), haugh unit (HU), albumen height (AH), yolk color (YC), egg grade (EG), eggshell strength (ESS), eggshell thickness (EST), eggshell color (ESC), egg shape index (ESI), relative yolk weight (RYW), relative eggshell weight (RESW), and relative albumen weight (RAW) were measured and calculated within 24 h. Egg weight, AH, HU, YC, and EG were measured by using the Egg Multi Tester (Model EMT-7300, Robotmation Co., Ltd, Japan), Egg grade included AA, A, B, and C, represented as score of 3, 2, 1, and 0, respectively. Eggshell color was measured by using the TSS OCR-PS (Technical Services and Supplies, England). Eggshell thickness was measured by using the Echo-meter (Model ETG-1061A, Karl Deutsch, Germany). Egg shape index was measured by using Egg Shape Index Tester (FHK, Fujihira Industry Co., Ltd, Japan), Eggshell strength was measured by using the Egg Force Reader (Orka Food Technology Ltd., Israel). Lastly, yolk and albumen were separated by egg separator and each was weighed, and the RYW, RAW, and RESW were calculated accordingly. Statistical Analyses The data were analyzed statistically using SPSS 16.0 Software for Windows (SPSS Inc. Chicago, IL). General linear model was used to analyze the main effects of lighting pattern and photoperiod alone, and the combination between lighting pattern and photoperiod. Duncan's test was used for multiple comparisons. The percentage was arcsine transformed before analysis. P < 0.05 was regarded as statistically significant. RESULTS Table 2 shows that egg production during 22 to 43 wk was not significantly affected by lighting pattern alone (P > 0.05). Egg-laying rate, EM, FER, and mortality rate were not significantly affected by photoperiod alone (P > 0.05), but AFI of 12 h was significantly higher than those in 14 and 16 h groups (P = 0.01). There were no significant effects on egg production of the native birds for the combination of lighting pattern and photoperiod during 22 to 43 wk (P > 0.05). Table 2. Effects of lighting pattern and photoperiod on egg production of Beijing You Chicken during 22 to 43 wks. Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.86 58.02 2.88 3.78 0.13 Intermittent 16 10.92 54.83 2.80 3.90 0 Continuous 14 10.69 56.41 2.72 3.93 0.09 Intermittent 14 10.84 55.30 2.73 3.97 0.09 Continuous 12 11.36 48.90 2.56 4.44 0.04 Intermittent 12 11.57 55.88 2.87 4.03 0.13 SEM 0.09 1.32 0.07 0.49 0.02 GLM analysis Arcsine transformation Lighting pattern Continuous 10.97 54.45 2.72 5.37 0.09 Intermittent 11.11 55.34 2.80 5.25 0.07 P value 0.46 0.74 0.58 0.74 0.90 Photoperiod 16 10.89b 56.43 2.84 4.76 0.07 14 10.76b 55.85 2.73 5.68 0.09 12 11.47a 52.39 2.72 5.49 0.09 P value 0.01 0.40 0.76 0.91 0.71 Lighting pattern × Photoperiod P value 0.94 0.25 0.53 0.16 0.96 Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.86 58.02 2.88 3.78 0.13 Intermittent 16 10.92 54.83 2.80 3.90 0 Continuous 14 10.69 56.41 2.72 3.93 0.09 Intermittent 14 10.84 55.30 2.73 3.97 0.09 Continuous 12 11.36 48.90 2.56 4.44 0.04 Intermittent 12 11.57 55.88 2.87 4.03 0.13 SEM 0.09 1.32 0.07 0.49 0.02 GLM analysis Arcsine transformation Lighting pattern Continuous 10.97 54.45 2.72 5.37 0.09 Intermittent 11.11 55.34 2.80 5.25 0.07 P value 0.46 0.74 0.58 0.74 0.90 Photoperiod 16 10.89b 56.43 2.84 4.76 0.07 14 10.76b 55.85 2.73 5.68 0.09 12 11.47a 52.39 2.72 5.49 0.09 P value 0.01 0.40 0.76 0.91 0.71 Lighting pattern × Photoperiod P value 0.94 0.25 0.53 0.16 0.96 Values with different letter superscripts in the same column mean significant difference (P < 0.05). AFI = average feed intake; FER = feed egg ratio. View Large Table 2. Effects of lighting pattern and photoperiod on egg production of Beijing You Chicken during 22 to 43 wks. Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.86 58.02 2.88 3.78 0.13 Intermittent 16 10.92 54.83 2.80 3.90 0 Continuous 14 10.69 56.41 2.72 3.93 0.09 Intermittent 14 10.84 55.30 2.73 3.97 0.09 Continuous 12 11.36 48.90 2.56 4.44 0.04 Intermittent 12 11.57 55.88 2.87 4.03 0.13 SEM 0.09 1.32 0.07 0.49 0.02 GLM analysis Arcsine transformation Lighting pattern Continuous 10.97 54.45 2.72 5.37 0.09 Intermittent 11.11 55.34 2.80 5.25 0.07 P value 0.46 0.74 0.58 0.74 0.90 Photoperiod 16 10.89b 56.43 2.84 4.76 0.07 14 10.76b 55.85 2.73 5.68 0.09 12 11.47a 52.39 2.72 5.49 0.09 P value 0.01 0.40 0.76 0.91 0.71 Lighting pattern × Photoperiod P value 0.94 0.25 0.53 0.16 0.96 Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.86 58.02 2.88 3.78 0.13 Intermittent 16 10.92 54.83 2.80 3.90 0 Continuous 14 10.69 56.41 2.72 3.93 0.09 Intermittent 14 10.84 55.30 2.73 3.97 0.09 Continuous 12 11.36 48.90 2.56 4.44 0.04 Intermittent 12 11.57 55.88 2.87 4.03 0.13 SEM 0.09 1.32 0.07 0.49 0.02 GLM analysis Arcsine transformation Lighting pattern Continuous 10.97 54.45 2.72 5.37 0.09 Intermittent 11.11 55.34 2.80 5.25 0.07 P value 0.46 0.74 0.58 0.74 0.90 Photoperiod 16 10.89b 56.43 2.84 4.76 0.07 14 10.76b 55.85 2.73 5.68 0.09 12 11.47a 52.39 2.72 5.49 0.09 P value 0.01 0.40 0.76 0.91 0.71 Lighting pattern × Photoperiod P value 0.94 0.25 0.53 0.16 0.96 Values with different letter superscripts in the same column mean significant difference (P < 0.05). AFI = average feed intake; FER = feed egg ratio. View Large Table 3 shows that AFI, egg-laying rate, and mortality rate were not significantly affected by lighting pattern, photoperiod alone, or in combination during 44 to 57 wk (P > 0.05), but EM and FER were significantly affected by lighting pattern, photoperiod alone, and in combination (P < 0.05). Egg mass was significantly higher (2.97 > 2.87 kg, P = 0.05) and FER was significantly lower (3.64 < 3.78, P = 0.03) in continuous groups than in intermittent groups. Egg mass was significantly higher (P = 0.02) and FER was significantly lower (P = 0.02) in 16 and 12 h groups than in 14 h groups. Egg mass was significantly higher (P = 0.04) and FER was significantly lower (P = 0.02) in continuous 16 h and continuous 12 h groups than those in continuous 14 h, intermittent 14 h, and intermittent 12 h groups. Table 3. Effects of lighting pattern and photoperiod on egg production of Beijing You Chicken during 44 to 57 wk. Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.63 56.60 3.03 3.51 0 Intermittent 16 10.73 55.68 2.91 3.70 0 Continuous 14 10.74 54.56 2.79 3.87 0.22 Intermittent 14 11.00 53.37 2.86 3.77 0.07 Continuous 12 11.00 55.82 3.10 3.55 0.07 Intermittent 12 11.00 53.21 2.85 3.86 0.21 SEM 0.10 0.74 0.02 0.03 0.03 GLM analysis Arcsine transformation Lighting pattern Continuous 10.79 55.66 2.97a 3.64b 0.09 Intermittent 10.91 54.09 2.87b 3.78a 0.09 P value 0.54 0.29 0.05 0.03 0.99 Photoperiod 16 10.68 56.14 2.97a 3.61b 0 14 10.87 53.97 2.82b 3.82a 0.14 12 11.00 54.51 2.98a 3.71b 0.14 P value 0.42 0.46 0.02 0.02 0.11 Lighting pattern × photoperiod Continuous 16 h 10.63 56.60 3.03a 3.51c 0 Continuous 14 h 10.74 54.56 2.79b 3.87a 0.22 Continuous 12 h 11.00 55.82 3.10a 3.55c 0.07 Intermittent 16 h 10.73 55.68 2.91a,b 3.70b 0 Intermittent 14 h 11.00 53.37 2.86b 3.77b 0.07 Intermittent 12 h 11.00 53.21 2.85b 3.86a 0.21 P value 0.87 0.88 0.04 0.02 0.17 Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.63 56.60 3.03 3.51 0 Intermittent 16 10.73 55.68 2.91 3.70 0 Continuous 14 10.74 54.56 2.79 3.87 0.22 Intermittent 14 11.00 53.37 2.86 3.77 0.07 Continuous 12 11.00 55.82 3.10 3.55 0.07 Intermittent 12 11.00 53.21 2.85 3.86 0.21 SEM 0.10 0.74 0.02 0.03 0.03 GLM analysis Arcsine transformation Lighting pattern Continuous 10.79 55.66 2.97a 3.64b 0.09 Intermittent 10.91 54.09 2.87b 3.78a 0.09 P value 0.54 0.29 0.05 0.03 0.99 Photoperiod 16 10.68 56.14 2.97a 3.61b 0 14 10.87 53.97 2.82b 3.82a 0.14 12 11.00 54.51 2.98a 3.71b 0.14 P value 0.42 0.46 0.02 0.02 0.11 Lighting pattern × photoperiod Continuous 16 h 10.63 56.60 3.03a 3.51c 0 Continuous 14 h 10.74 54.56 2.79b 3.87a 0.22 Continuous 12 h 11.00 55.82 3.10a 3.55c 0.07 Intermittent 16 h 10.73 55.68 2.91a,b 3.70b 0 Intermittent 14 h 11.00 53.37 2.86b 3.77b 0.07 Intermittent 12 h 11.00 53.21 2.85b 3.86a 0.21 P value 0.87 0.88 0.04 0.02 0.17 a–cValues with different letter superscripts in the same column mean significant difference (P < 0.05). AFI = average feed intake; FER = feed egg ratio. View Large Table 3. Effects of lighting pattern and photoperiod on egg production of Beijing You Chicken during 44 to 57 wk. Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.63 56.60 3.03 3.51 0 Intermittent 16 10.73 55.68 2.91 3.70 0 Continuous 14 10.74 54.56 2.79 3.87 0.22 Intermittent 14 11.00 53.37 2.86 3.77 0.07 Continuous 12 11.00 55.82 3.10 3.55 0.07 Intermittent 12 11.00 53.21 2.85 3.86 0.21 SEM 0.10 0.74 0.02 0.03 0.03 GLM analysis Arcsine transformation Lighting pattern Continuous 10.79 55.66 2.97a 3.64b 0.09 Intermittent 10.91 54.09 2.87b 3.78a 0.09 P value 0.54 0.29 0.05 0.03 0.99 Photoperiod 16 10.68 56.14 2.97a 3.61b 0 14 10.87 53.97 2.82b 3.82a 0.14 12 11.00 54.51 2.98a 3.71b 0.14 P value 0.42 0.46 0.02 0.02 0.11 Lighting pattern × photoperiod Continuous 16 h 10.63 56.60 3.03a 3.51c 0 Continuous 14 h 10.74 54.56 2.79b 3.87a 0.22 Continuous 12 h 11.00 55.82 3.10a 3.55c 0.07 Intermittent 16 h 10.73 55.68 2.91a,b 3.70b 0 Intermittent 14 h 11.00 53.37 2.86b 3.77b 0.07 Intermittent 12 h 11.00 53.21 2.85b 3.86a 0.21 P value 0.87 0.88 0.04 0.02 0.17 Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.63 56.60 3.03 3.51 0 Intermittent 16 10.73 55.68 2.91 3.70 0 Continuous 14 10.74 54.56 2.79 3.87 0.22 Intermittent 14 11.00 53.37 2.86 3.77 0.07 Continuous 12 11.00 55.82 3.10 3.55 0.07 Intermittent 12 11.00 53.21 2.85 3.86 0.21 SEM 0.10 0.74 0.02 0.03 0.03 GLM analysis Arcsine transformation Lighting pattern Continuous 10.79 55.66 2.97a 3.64b 0.09 Intermittent 10.91 54.09 2.87b 3.78a 0.09 P value 0.54 0.29 0.05 0.03 0.99 Photoperiod 16 10.68 56.14 2.97a 3.61b 0 14 10.87 53.97 2.82b 3.82a 0.14 12 11.00 54.51 2.98a 3.71b 0.14 P value 0.42 0.46 0.02 0.02 0.11 Lighting pattern × photoperiod Continuous 16 h 10.63 56.60 3.03a 3.51c 0 Continuous 14 h 10.74 54.56 2.79b 3.87a 0.22 Continuous 12 h 11.00 55.82 3.10a 3.55c 0.07 Intermittent 16 h 10.73 55.68 2.91a,b 3.70b 0 Intermittent 14 h 11.00 53.37 2.86b 3.77b 0.07 Intermittent 12 h 11.00 53.21 2.85b 3.86a 0.21 P value 0.87 0.88 0.04 0.02 0.17 a–cValues with different letter superscripts in the same column mean significant difference (P < 0.05). AFI = average feed intake; FER = feed egg ratio. View Large Table 4 shows that the egg production during 22 to 57 wk was not significantly affected by lighting pattern alone (P > 0.05). Egg-laying rate, EM, FER, and mortality rate were not significantly affected by photoperiod alone (P > 0.05), but AFI was significantly higher in 12 h than those in 14 and 16 h groups (P = 0.01). There were no significant effects on the egg production for the combination of lighting pattern and photoperiod during 22 to 57 wk (P > 0.05). Table 4. Effects of lighting pattern and photoperiod on egg production of Beijing You Chicken during 22 to 57 wk. Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.77 57.47 2.94 3.67 0.08 Intermittent 16 10.85 55.16 2.84 3.83 0 Continuous 14 10.71 55.69 2.75 3.89 0.14 Intermittent 14 10.91 54.55 2.78 3.92 0.08 Continuous 12 11.21 51.59 2.77 4.05 0.05 Intermittent 12 11.35 54.84 2.87 3.95 0.16 SEM 0.07 0.85 0.05 0.30 0.02 GLM analysis Arcsine transformation Lighting pattern Continuous 10.90 54.92 2.82 4.70 0.09 Intermittent 11.04 54.85 2.83 4.68 0.08 P value 0.34 0.97 0.90 0.97 0.79 Photoperiod 16 10.81b 56.31 2.89 4.31 0.03 14 10.81b 55.12 2.77 4.96 0.03 12 11.29a 53.22 2.82 4.80 0.03 P value 0.01 0.33 0.55 0.66 0.23 Lighting pattern × photoperiod P value 0.94 0.38 0.69 0.96 0.08 Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.77 57.47 2.94 3.67 0.08 Intermittent 16 10.85 55.16 2.84 3.83 0 Continuous 14 10.71 55.69 2.75 3.89 0.14 Intermittent 14 10.91 54.55 2.78 3.92 0.08 Continuous 12 11.21 51.59 2.77 4.05 0.05 Intermittent 12 11.35 54.84 2.87 3.95 0.16 SEM 0.07 0.85 0.05 0.30 0.02 GLM analysis Arcsine transformation Lighting pattern Continuous 10.90 54.92 2.82 4.70 0.09 Intermittent 11.04 54.85 2.83 4.68 0.08 P value 0.34 0.97 0.90 0.97 0.79 Photoperiod 16 10.81b 56.31 2.89 4.31 0.03 14 10.81b 55.12 2.77 4.96 0.03 12 11.29a 53.22 2.82 4.80 0.03 P value 0.01 0.33 0.55 0.66 0.23 Lighting pattern × photoperiod P value 0.94 0.38 0.69 0.96 0.08 a,bValues with different letter superscripts in the same column mean significant difference (P < 0.05). AFI = average feed intake; FER = feed egg ratio. View Large Table 4. Effects of lighting pattern and photoperiod on egg production of Beijing You Chicken during 22 to 57 wk. Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.77 57.47 2.94 3.67 0.08 Intermittent 16 10.85 55.16 2.84 3.83 0 Continuous 14 10.71 55.69 2.75 3.89 0.14 Intermittent 14 10.91 54.55 2.78 3.92 0.08 Continuous 12 11.21 51.59 2.77 4.05 0.05 Intermittent 12 11.35 54.84 2.87 3.95 0.16 SEM 0.07 0.85 0.05 0.30 0.02 GLM analysis Arcsine transformation Lighting pattern Continuous 10.90 54.92 2.82 4.70 0.09 Intermittent 11.04 54.85 2.83 4.68 0.08 P value 0.34 0.97 0.90 0.97 0.79 Photoperiod 16 10.81b 56.31 2.89 4.31 0.03 14 10.81b 55.12 2.77 4.96 0.03 12 11.29a 53.22 2.82 4.80 0.03 P value 0.01 0.33 0.55 0.66 0.23 Lighting pattern × photoperiod P value 0.94 0.38 0.69 0.96 0.08 Lighting pattern Photoperiod/(h) AFI/(kg) Egg-laying rate/(%) Egg mass/(kg) FER/(kg:kg) Mortality rate/(%) Continuous 16 10.77 57.47 2.94 3.67 0.08 Intermittent 16 10.85 55.16 2.84 3.83 0 Continuous 14 10.71 55.69 2.75 3.89 0.14 Intermittent 14 10.91 54.55 2.78 3.92 0.08 Continuous 12 11.21 51.59 2.77 4.05 0.05 Intermittent 12 11.35 54.84 2.87 3.95 0.16 SEM 0.07 0.85 0.05 0.30 0.02 GLM analysis Arcsine transformation Lighting pattern Continuous 10.90 54.92 2.82 4.70 0.09 Intermittent 11.04 54.85 2.83 4.68 0.08 P value 0.34 0.97 0.90 0.97 0.79 Photoperiod 16 10.81b 56.31 2.89 4.31 0.03 14 10.81b 55.12 2.77 4.96 0.03 12 11.29a 53.22 2.82 4.80 0.03 P value 0.01 0.33 0.55 0.66 0.23 Lighting pattern × photoperiod P value 0.94 0.38 0.69 0.96 0.08 a,bValues with different letter superscripts in the same column mean significant difference (P < 0.05). AFI = average feed intake; FER = feed egg ratio. View Large Table 5 shows that there were significant effects on EST, AH, HU, and EG by the lighting pattern alone (P < 0.05) at 37 wk. Eggshell thickness, AH, HU, and EG in continuous groups were significantly lower than those in intermittent groups (P = 0.01, P = 0.04, P = 0.05, and P = 0.03). Egg weight and AH were significantly affected by photoperiod alone (P < 0.05). Egg weight and AH in 12 h groups were significantly higher than those in 16 and 14 h groups (P = 0.02 and P = 0.01). There were no significant effects on the egg quality for the combination of lighting pattern and photoperiod at 37 wk (P > 0.05). Table 5. Effects of lighting pattern and photoperiod on egg quality of Beijing You Chicken at 37 wk (n = 30). Photoperiod ESS/ EST/ ESC/ AH/ RYW RESW RAW Lighting pattern /(h) EW/(g) (kg/cm2) (mm) (%) (mm) HU YC EG ESI /(%) /(%) /(%) Continuous 16 47.64 4.35 0.40 46.95 4.06 63.82 7.20 2.07 1.31 29.22 13.28 57.51 Intermittent 16 50.71 4.36 0.44 49.80 4.42 65.61 7.07 2.13 1.33 28.68 13.36 57.96 Continuous 14 50.28 4.63 0.41 49.44 3.87 60.53 7.67 1.93 1.33 30.51 13.52 55.97 Intermittent 14 49.43 4.19 0.43 46.09 4.53 67.87 6.93 2.33 1.33 29.10 13.13 57.77 Continuous 12 52.61 4.35 0.40 51.01 4.73 67.17 7.20 2.13 1.34 29.07 13.04 57.89 Intermittent 12 52.31 4.39 0.42 52.07 5.49 75.45 7.27 2.80 1.35 30.01 13.11 56.88 SEM 0.52 0.07 0.004 0.74 0.15 1.47 0.10 0.09 0.01 0.34 0.16 0.46 GLM analysis Arcsine transformation Lighting pattern Continuous 50.18 4.44 0.40b 49.13 4.22b 63.84b 7.36 2.04b 1.32 29.59 13.28 57.12 Intermittent 50.82 4.31 0.43a 49.32 4.81a 69.64a 7.08 2.42a 1.33 29.27 13.20 57.53 P value 0.52 0.34 0.01 0.89 0.04 0.05 0.21 0.03 0.51 0.69 0.80 0.78 Photoperiod (h) 16 49.17b 4.35 0.42 48.37 4.24b 64.71 7.13 2.10 1.32 28.95 13.32 57.73 14 49.85b 4.41 0.42 47.76 4.19b 64.19 7.30 2.13 1.33 29.81 13.32 56.87 12 52.46a 4.37 0.41 51.54 5.11a 71.31 7.23 2.47 1.34 29.54 13.08 57.39 P value 0.02 0.95 0.23 0.08 0.01 0.08 0.81 0.16 0.15 0.50 0.77 0.50 Lighting pattern × photoperiod P value 0.23 0.29 0.10 0.21 0.83 0.61 0.27 0.36 0.78 0.12 0.78 0.17 Photoperiod ESS/ EST/ ESC/ AH/ RYW RESW RAW Lighting pattern /(h) EW/(g) (kg/cm2) (mm) (%) (mm) HU YC EG ESI /(%) /(%) /(%) Continuous 16 47.64 4.35 0.40 46.95 4.06 63.82 7.20 2.07 1.31 29.22 13.28 57.51 Intermittent 16 50.71 4.36 0.44 49.80 4.42 65.61 7.07 2.13 1.33 28.68 13.36 57.96 Continuous 14 50.28 4.63 0.41 49.44 3.87 60.53 7.67 1.93 1.33 30.51 13.52 55.97 Intermittent 14 49.43 4.19 0.43 46.09 4.53 67.87 6.93 2.33 1.33 29.10 13.13 57.77 Continuous 12 52.61 4.35 0.40 51.01 4.73 67.17 7.20 2.13 1.34 29.07 13.04 57.89 Intermittent 12 52.31 4.39 0.42 52.07 5.49 75.45 7.27 2.80 1.35 30.01 13.11 56.88 SEM 0.52 0.07 0.004 0.74 0.15 1.47 0.10 0.09 0.01 0.34 0.16 0.46 GLM analysis Arcsine transformation Lighting pattern Continuous 50.18 4.44 0.40b 49.13 4.22b 63.84b 7.36 2.04b 1.32 29.59 13.28 57.12 Intermittent 50.82 4.31 0.43a 49.32 4.81a 69.64a 7.08 2.42a 1.33 29.27 13.20 57.53 P value 0.52 0.34 0.01 0.89 0.04 0.05 0.21 0.03 0.51 0.69 0.80 0.78 Photoperiod (h) 16 49.17b 4.35 0.42 48.37 4.24b 64.71 7.13 2.10 1.32 28.95 13.32 57.73 14 49.85b 4.41 0.42 47.76 4.19b 64.19 7.30 2.13 1.33 29.81 13.32 56.87 12 52.46a 4.37 0.41 51.54 5.11a 71.31 7.23 2.47 1.34 29.54 13.08 57.39 P value 0.02 0.95 0.23 0.08 0.01 0.08 0.81 0.16 0.15 0.50 0.77 0.50 Lighting pattern × photoperiod P value 0.23 0.29 0.10 0.21 0.83 0.61 0.27 0.36 0.78 0.12 0.78 0.17 a,bValues with different letter superscripts in the same column mean significant difference (P < 0.05). EW = egg weight; ESS = eggshell strength; EST = eggshell thickness; ESC = eggshell color; AH = albumen height; HU = Haugh unit; YC = yolk color; EG = egg grade; ESI = egg shape index; RYW = relative yolk weight; RESW = relative eggshell weight; RAW = relative albumen weight. View Large Table 5. Effects of lighting pattern and photoperiod on egg quality of Beijing You Chicken at 37 wk (n = 30). Photoperiod ESS/ EST/ ESC/ AH/ RYW RESW RAW Lighting pattern /(h) EW/(g) (kg/cm2) (mm) (%) (mm) HU YC EG ESI /(%) /(%) /(%) Continuous 16 47.64 4.35 0.40 46.95 4.06 63.82 7.20 2.07 1.31 29.22 13.28 57.51 Intermittent 16 50.71 4.36 0.44 49.80 4.42 65.61 7.07 2.13 1.33 28.68 13.36 57.96 Continuous 14 50.28 4.63 0.41 49.44 3.87 60.53 7.67 1.93 1.33 30.51 13.52 55.97 Intermittent 14 49.43 4.19 0.43 46.09 4.53 67.87 6.93 2.33 1.33 29.10 13.13 57.77 Continuous 12 52.61 4.35 0.40 51.01 4.73 67.17 7.20 2.13 1.34 29.07 13.04 57.89 Intermittent 12 52.31 4.39 0.42 52.07 5.49 75.45 7.27 2.80 1.35 30.01 13.11 56.88 SEM 0.52 0.07 0.004 0.74 0.15 1.47 0.10 0.09 0.01 0.34 0.16 0.46 GLM analysis Arcsine transformation Lighting pattern Continuous 50.18 4.44 0.40b 49.13 4.22b 63.84b 7.36 2.04b 1.32 29.59 13.28 57.12 Intermittent 50.82 4.31 0.43a 49.32 4.81a 69.64a 7.08 2.42a 1.33 29.27 13.20 57.53 P value 0.52 0.34 0.01 0.89 0.04 0.05 0.21 0.03 0.51 0.69 0.80 0.78 Photoperiod (h) 16 49.17b 4.35 0.42 48.37 4.24b 64.71 7.13 2.10 1.32 28.95 13.32 57.73 14 49.85b 4.41 0.42 47.76 4.19b 64.19 7.30 2.13 1.33 29.81 13.32 56.87 12 52.46a 4.37 0.41 51.54 5.11a 71.31 7.23 2.47 1.34 29.54 13.08 57.39 P value 0.02 0.95 0.23 0.08 0.01 0.08 0.81 0.16 0.15 0.50 0.77 0.50 Lighting pattern × photoperiod P value 0.23 0.29 0.10 0.21 0.83 0.61 0.27 0.36 0.78 0.12 0.78 0.17 Photoperiod ESS/ EST/ ESC/ AH/ RYW RESW RAW Lighting pattern /(h) EW/(g) (kg/cm2) (mm) (%) (mm) HU YC EG ESI /(%) /(%) /(%) Continuous 16 47.64 4.35 0.40 46.95 4.06 63.82 7.20 2.07 1.31 29.22 13.28 57.51 Intermittent 16 50.71 4.36 0.44 49.80 4.42 65.61 7.07 2.13 1.33 28.68 13.36 57.96 Continuous 14 50.28 4.63 0.41 49.44 3.87 60.53 7.67 1.93 1.33 30.51 13.52 55.97 Intermittent 14 49.43 4.19 0.43 46.09 4.53 67.87 6.93 2.33 1.33 29.10 13.13 57.77 Continuous 12 52.61 4.35 0.40 51.01 4.73 67.17 7.20 2.13 1.34 29.07 13.04 57.89 Intermittent 12 52.31 4.39 0.42 52.07 5.49 75.45 7.27 2.80 1.35 30.01 13.11 56.88 SEM 0.52 0.07 0.004 0.74 0.15 1.47 0.10 0.09 0.01 0.34 0.16 0.46 GLM analysis Arcsine transformation Lighting pattern Continuous 50.18 4.44 0.40b 49.13 4.22b 63.84b 7.36 2.04b 1.32 29.59 13.28 57.12 Intermittent 50.82 4.31 0.43a 49.32 4.81a 69.64a 7.08 2.42a 1.33 29.27 13.20 57.53 P value 0.52 0.34 0.01 0.89 0.04 0.05 0.21 0.03 0.51 0.69 0.80 0.78 Photoperiod (h) 16 49.17b 4.35 0.42 48.37 4.24b 64.71 7.13 2.10 1.32 28.95 13.32 57.73 14 49.85b 4.41 0.42 47.76 4.19b 64.19 7.30 2.13 1.33 29.81 13.32 56.87 12 52.46a 4.37 0.41 51.54 5.11a 71.31 7.23 2.47 1.34 29.54 13.08 57.39 P value 0.02 0.95 0.23 0.08 0.01 0.08 0.81 0.16 0.15 0.50 0.77 0.50 Lighting pattern × photoperiod P value 0.23 0.29 0.10 0.21 0.83 0.61 0.27 0.36 0.78 0.12 0.78 0.17 a,bValues with different letter superscripts in the same column mean significant difference (P < 0.05). EW = egg weight; ESS = eggshell strength; EST = eggshell thickness; ESC = eggshell color; AH = albumen height; HU = Haugh unit; YC = yolk color; EG = egg grade; ESI = egg shape index; RYW = relative yolk weight; RESW = relative eggshell weight; RAW = relative albumen weight. View Large Table 6 shows that there were no significant effects on most of egg quality parameters by lighting pattern, photoperiod alone, and in combination at 57 wk (P > 0.05), except for RAW. Relative albumen weight in 12 h groups was significantly lower than those in 16 and 14 h groups (P = 0.02). Egg weight and AH in 12 h groups were higher than those in 16 and 14 h groups, close to the significant level (P = 0.07 and P = 0.09). Table 6. Effects of lighting pattern and photoperiod on egg quality of BYC at 57 wk (n = 30). Photoperiod ESS/ EST/ ESC/ AH/ RYW/ RESW/ RAW/ Lighting pattern /(h) EW/(g) (kg/cm2) (mm) (%) (mm) HU YC EG ESI (%) (%) (%) Continuous 16 52.35 3.34 0.40 44.23 4.10 61.09 6.13 1.87 1.38 31.46 12.86 61.12 Intermittent 16 54.79 3.49 0.40 49.83 4.59 63.80 6.13 1.93 1.37 31.03 12.51 57.03 Continuous 14 54.83 3.35 0.40 45.94 3.96 60.71 6.00 1.60 1.59 31.18 12.57 57.31 Intermittent 14 52.41 3.07 0.39 47.80 4.33 64.48 6.00 2.07 1.38 32.07 12.56 61.76 Continuous 12 55.32 3.36 0.40 48.95 4.98 69.73 5.60 2.33 1.35 30.75 12.68 55.85 Intermittent 12 56.93 3.40 0.39 48.95 4.94 67.22 6.13 2.07 1.39 30.40 12.24 53.84 SEM 0.53 0.07 0.002 0.74 0.16 1.54 0.11 0.09 0.04 0.26 0.13 0.84 GLM analysis Arcsine transformation Lighting pattern Continuous 54.17 3.35 0.39 46.38 4.35 63.84 5.91 1.93 1.44 31.13 12.71 58.09 Intermittent 54.71 3.32 0.39 48.86 4.62 65.17 6.09 2.02 1.38 31.17 12.44 57.54 P value 0.60 0.85 0.18 0.09 0.38 0.67 0.43 0.64 0.46 0.41 0.31 0.74 Photoperiod (h) 16 53.57 3.42 0.40 47.03 4.35 62.45 6.13 1.90 1.38 31.25 12.68 59.08a 14 53.62 3.21 0.39 46.87 4.14 62.59 6.00 1.83 1.48 31.62 12.57 59.54a 12 56.13 3.38 0.40 48.95 4.96 68.48 5.87 2.00 1.37 30.58 12.46 54.84b P value 0.07 0.48 0.74 0.44 0.09 0.19 0.62 0.25 0.43 0.12 0.79 0.02 Lighting pattern × Photoperiod P value 0.13 0.46 0.26 0.29 0.76 0.68 0.53 0.29 0.44 0.60 0.78 0.23 Photoperiod ESS/ EST/ ESC/ AH/ RYW/ RESW/ RAW/ Lighting pattern /(h) EW/(g) (kg/cm2) (mm) (%) (mm) HU YC EG ESI (%) (%) (%) Continuous 16 52.35 3.34 0.40 44.23 4.10 61.09 6.13 1.87 1.38 31.46 12.86 61.12 Intermittent 16 54.79 3.49 0.40 49.83 4.59 63.80 6.13 1.93 1.37 31.03 12.51 57.03 Continuous 14 54.83 3.35 0.40 45.94 3.96 60.71 6.00 1.60 1.59 31.18 12.57 57.31 Intermittent 14 52.41 3.07 0.39 47.80 4.33 64.48 6.00 2.07 1.38 32.07 12.56 61.76 Continuous 12 55.32 3.36 0.40 48.95 4.98 69.73 5.60 2.33 1.35 30.75 12.68 55.85 Intermittent 12 56.93 3.40 0.39 48.95 4.94 67.22 6.13 2.07 1.39 30.40 12.24 53.84 SEM 0.53 0.07 0.002 0.74 0.16 1.54 0.11 0.09 0.04 0.26 0.13 0.84 GLM analysis Arcsine transformation Lighting pattern Continuous 54.17 3.35 0.39 46.38 4.35 63.84 5.91 1.93 1.44 31.13 12.71 58.09 Intermittent 54.71 3.32 0.39 48.86 4.62 65.17 6.09 2.02 1.38 31.17 12.44 57.54 P value 0.60 0.85 0.18 0.09 0.38 0.67 0.43 0.64 0.46 0.41 0.31 0.74 Photoperiod (h) 16 53.57 3.42 0.40 47.03 4.35 62.45 6.13 1.90 1.38 31.25 12.68 59.08a 14 53.62 3.21 0.39 46.87 4.14 62.59 6.00 1.83 1.48 31.62 12.57 59.54a 12 56.13 3.38 0.40 48.95 4.96 68.48 5.87 2.00 1.37 30.58 12.46 54.84b P value 0.07 0.48 0.74 0.44 0.09 0.19 0.62 0.25 0.43 0.12 0.79 0.02 Lighting pattern × Photoperiod P value 0.13 0.46 0.26 0.29 0.76 0.68 0.53 0.29 0.44 0.60 0.78 0.23 a,bValues with different letter superscripts in the same column mean significant difference (P < 0.05). EW = egg weight; ESS = eggshell strength; EST = eggshell thickness; ESC = eggshell color; AH = albumen height; HU = Haugh unit; YC = yolk color; EG = egg grade; ESI = egg shape index; RYW = relative yolk weight; RESW = relative eggshell weight; RAW = relative albumen weight. View Large Table 6. Effects of lighting pattern and photoperiod on egg quality of BYC at 57 wk (n = 30). Photoperiod ESS/ EST/ ESC/ AH/ RYW/ RESW/ RAW/ Lighting pattern /(h) EW/(g) (kg/cm2) (mm) (%) (mm) HU YC EG ESI (%) (%) (%) Continuous 16 52.35 3.34 0.40 44.23 4.10 61.09 6.13 1.87 1.38 31.46 12.86 61.12 Intermittent 16 54.79 3.49 0.40 49.83 4.59 63.80 6.13 1.93 1.37 31.03 12.51 57.03 Continuous 14 54.83 3.35 0.40 45.94 3.96 60.71 6.00 1.60 1.59 31.18 12.57 57.31 Intermittent 14 52.41 3.07 0.39 47.80 4.33 64.48 6.00 2.07 1.38 32.07 12.56 61.76 Continuous 12 55.32 3.36 0.40 48.95 4.98 69.73 5.60 2.33 1.35 30.75 12.68 55.85 Intermittent 12 56.93 3.40 0.39 48.95 4.94 67.22 6.13 2.07 1.39 30.40 12.24 53.84 SEM 0.53 0.07 0.002 0.74 0.16 1.54 0.11 0.09 0.04 0.26 0.13 0.84 GLM analysis Arcsine transformation Lighting pattern Continuous 54.17 3.35 0.39 46.38 4.35 63.84 5.91 1.93 1.44 31.13 12.71 58.09 Intermittent 54.71 3.32 0.39 48.86 4.62 65.17 6.09 2.02 1.38 31.17 12.44 57.54 P value 0.60 0.85 0.18 0.09 0.38 0.67 0.43 0.64 0.46 0.41 0.31 0.74 Photoperiod (h) 16 53.57 3.42 0.40 47.03 4.35 62.45 6.13 1.90 1.38 31.25 12.68 59.08a 14 53.62 3.21 0.39 46.87 4.14 62.59 6.00 1.83 1.48 31.62 12.57 59.54a 12 56.13 3.38 0.40 48.95 4.96 68.48 5.87 2.00 1.37 30.58 12.46 54.84b P value 0.07 0.48 0.74 0.44 0.09 0.19 0.62 0.25 0.43 0.12 0.79 0.02 Lighting pattern × Photoperiod P value 0.13 0.46 0.26 0.29 0.76 0.68 0.53 0.29 0.44 0.60 0.78 0.23 Photoperiod ESS/ EST/ ESC/ AH/ RYW/ RESW/ RAW/ Lighting pattern /(h) EW/(g) (kg/cm2) (mm) (%) (mm) HU YC EG ESI (%) (%) (%) Continuous 16 52.35 3.34 0.40 44.23 4.10 61.09 6.13 1.87 1.38 31.46 12.86 61.12 Intermittent 16 54.79 3.49 0.40 49.83 4.59 63.80 6.13 1.93 1.37 31.03 12.51 57.03 Continuous 14 54.83 3.35 0.40 45.94 3.96 60.71 6.00 1.60 1.59 31.18 12.57 57.31 Intermittent 14 52.41 3.07 0.39 47.80 4.33 64.48 6.00 2.07 1.38 32.07 12.56 61.76 Continuous 12 55.32 3.36 0.40 48.95 4.98 69.73 5.60 2.33 1.35 30.75 12.68 55.85 Intermittent 12 56.93 3.40 0.39 48.95 4.94 67.22 6.13 2.07 1.39 30.40 12.24 53.84 SEM 0.53 0.07 0.002 0.74 0.16 1.54 0.11 0.09 0.04 0.26 0.13 0.84 GLM analysis Arcsine transformation Lighting pattern Continuous 54.17 3.35 0.39 46.38 4.35 63.84 5.91 1.93 1.44 31.13 12.71 58.09 Intermittent 54.71 3.32 0.39 48.86 4.62 65.17 6.09 2.02 1.38 31.17 12.44 57.54 P value 0.60 0.85 0.18 0.09 0.38 0.67 0.43 0.64 0.46 0.41 0.31 0.74 Photoperiod (h) 16 53.57 3.42 0.40 47.03 4.35 62.45 6.13 1.90 1.38 31.25 12.68 59.08a 14 53.62 3.21 0.39 46.87 4.14 62.59 6.00 1.83 1.48 31.62 12.57 59.54a 12 56.13 3.38 0.40 48.95 4.96 68.48 5.87 2.00 1.37 30.58 12.46 54.84b P value 0.07 0.48 0.74 0.44 0.09 0.19 0.62 0.25 0.43 0.12 0.79 0.02 Lighting pattern × Photoperiod P value 0.13 0.46 0.26 0.29 0.76 0.68 0.53 0.29 0.44 0.60 0.78 0.23 a,bValues with different letter superscripts in the same column mean significant difference (P < 0.05). EW = egg weight; ESS = eggshell strength; EST = eggshell thickness; ESC = eggshell color; AH = albumen height; HU = Haugh unit; YC = yolk color; EG = egg grade; ESI = egg shape index; RYW = relative yolk weight; RESW = relative eggshell weight; RAW = relative albumen weight. View Large DISCUSSION Lighting had important effects on growth and development, performance, and healthy condition in poultry (Zhang 2008). There has been a lot of research about the effects of intermittent lighting on performance of birds (Rowland 1985), but mostly concentrating on commercial high-producing poultry, not on traditional or native chicken. Freitas et al. (2005) compared a kind of intermittent lighting, natural gradual increasing light, and a kind of continuous lighting, and found that the intermittent lighting and natural gradual increasing lighting did not affect the egg production of the layers in open house. Leeson et al. (2005) compared the effects of various step-down lighting regimens in the rearing period on rearing and laying performance in commercial laying pullets, and found that step-down lighting had no significant improvement in egg numbers, egg mass, etc. Gewehr and Freitas (2007) showed that intermittent lighting did not affect the performance and could be an alternative way of lighting for the layers. Effects of photoperiod on birds mainly reflect in establishment of circadian rhythm (Dawson et al., 2001) and regulation of prolactin concentration (Johnston 2004). In this present study, 2 lighting patterns (continuous and intermittent lighting) and 3 photoperiods (16, 14, 12 h) were arranged to study the effects of lighting pattern, photoperiod alone, and in combination on egg production of BYC, and found that egg-laying rate, EM, and FER during 22 to 43 and 22 to 57 wk were not significantly affected by lighting pattern alone (P > 0.05), which supported the above that intermittent lighting did not affect the egg production of laying hens, but AFI in 12 h groups was significantly higher than those in 14 and 16 h groups (P < 0.05). Ma et al. (2011) studied the effects of photoperiod on feeding duration and feed intake of BYC, and found that the shorter the photoperiod, the longer the feeding duration and feed intake of the birds, whereas Lewis et al. (2007) reported that the feed intake in the laying period was not significantly affected by the rearing photoperiod for Lohmann Brown. The higher AFI here may be due to the birds having the capability of perceiving day-length and adjusting feed intake, which needs further research. Egg mass and FER are important indicators of egg production. During 44 to 57 wk, EM was significantly higher (2.97 > 2.87, P = 0.05) and FER was significantly lower (3.64 < 3.78, P = 0.03) in continuous groups than in intermittent groups, which suggested that continuous lighting was better for the egg production in late laying period of the bird. The mortality rate of the birds during 22 to 43, 44 to 57, and 22 to 57 wk were not significantly affected by the lighting pattern, photoperiod alone, and in combination, which was partly in agreement with Lewis et al. (2007) who reported that mortality of the layers during laying phases was unaffected by the photoperiod, whereas properly designed intermittent lighting (8L:6D:2L:8D) could reduce mortality of Japanese quail (Zahoor et al., 2011). Photoperiod affected the egg weight, yolk ratio, and eggshell thickness (Lewis and Morris 2006), and also the sexual maturation of the layers (Chen et al., 2007). Pan et al. (2007) reported that both light increasing ways and photoperiod affected the egg quality of Hy-Line Brown layers, and this effect may be through affecting the oviduct shape and further influencing on egg quality (Wang et al., 2009). Shen et al. (2012) compared two continuous lighting and two intermittent lighting on egg quality of BYC at 28, 38, and 48 wk of age, and found that the EW and RYW were 1.63% and 8.91% higher in intermittent 12 h group than in continuous 16 h group, respectively. In this study there were no significant effects on most of egg quality parameters by lighting pattern, photoperiod alone, and in combination at 57 wk (P > 0.05), but RAW in 12 h groups was significantly lower than those in 16 and 14 h groups (P = 0.02). Zhang et al. (2009) compared the egg quality between BYC and Lohmann Pink when their egg-laying rate reached 50%, and found that there were significant differences in most of parameters including EW, ESC, ESS, EST, AH, HU, YC, etc., except RESW, which indicated that the breed is an important factor affecting egg quality. Here this present study indicated that there had significant effects on EST, AH, HU, and EG by the lighting pattern alone (P < 0.05) at 37 wk of age. Eggshell thickness, AH, HU, and EG in continuous lighting groups were significantly lower than those in intermittent lighting groups (P < 0.05). Albumen height and HU are important parameters reflecting the egg freshness and albumen quality, eggshell thickness is related with the shelf life of eggs, egg grade reflects the freshness of eggs, so higher EST, AH, HU and EG in intermittent lighting groups indicates better egg quality, which may be related to less egg production during 44 to 57 wk. Jácome et al. (2014) studied that commercial layers in Brazil are photo-stimulated with more than 12 h of light, and suggested the lighting programs influenced egg production, but not egg quality indices. In this study, EW in 12 h groups was significantly higher than those in 16 and 14 h groups (P < 0.05), considering higher AFI in 12 h groups above, we suggest 12 h lighting is enough for meeting the requirement of egg production and egg quality of the native chicken. We previously used 6 photoperiodic treatments to study the egg laying of BYC during 20 to 61 wk (Geng et al. 2014), including 16L:8D (0600 to 2200 h), 12L:2D:4L:6D, 8L:4D:4L:8D, 16L:8D (0300 to 1900 h),14L:10D, and 18L:6D, and found that average egg-laying rate of 12L:2D:4L:6D group (62.91%) and 14L:10D (61.74%) were significantly higher than others except 8L:4D:4L:8D group (61.13%), though no change in photoperiod from the rearing to production phase for this group (12 to 12 L). In this present study, we had the same 12 L schedule for groups 5 and 6 (12L:12D and 8L:4D:4L:8D, respectively), and found that 12 L significantly improved the AFI of chicken during 22 to 57 wk, EM during 44 to 57 wk, and decreased RAW at 57 wk, suggesting that no change in photoperiod from rearing to the production phase will have long-lasting effects on egg production or egg quality, the related mechanism needs further research. CONCLUSION The present study indicated that 1) the egg production was not significantly affected by lighting pattern alone during 22 to 57 wk (P > 0.05), but the photoperiod significantly affected AFI (P < 0.05); 2) continuous lighting is better for the egg production during 44 to 57 wk, and intermittent lighting is better for egg quality of the native bird at 37 wk; 3) 12 h lighting is enough for meeting the requirement of the native chicken during the laying period; 4) no change in photoperiod from the rearing to the production phase (12 to 12 L) will have long-lasting effects on egg production or egg quality under the present condition. Acknowledgements The authors wish to thank National Natural Science Funds (grant numbers 31372353, 30972128), Beijing Natural Science Fund (grant number 6102010) for providing financial supports, and staff from BYC Breeder Farm for feeding and management of the experimental birds. REFERENCES Chen H. , Huang R. L. , Zhang H. X. , Di K. 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SAADC 2011 . 626 – 630 in Strategies and Challenges for Sustainable Animal Agriculture-Crop Systems, Volume III : full papers. Proc. 3rd International Conference on Sustainable Animal Agriculture for Developing Countries . Nakhon Ratchasima , Thailand . © 2018 Poultry Science Association Inc. This article is published and distributed under the term of oxford University Press, standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)

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Poultry ScienceOxford University Press

Published: Jun 22, 2018

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