British Poultry Science

Morris, T. R.

doi: 10.1080/00071669608417831pmid: 8833522

Abstract 1. The theme of the lecture is that research in poultry science has moved too far in the direction of molecular biology and away from studies with whole animals. This has happened partly because exciting prospects are opening up in the field of gene manipulation but mainly because of the use of inappropriate referees to evaluate research proposals. 2. Agricultural research is defined as work intended to benefit agriculture and directed towards those problems which seem capable of solution. Science research is something else. Too much of the money allocated for agricultural and biotechnology research is being spent on science research. The system of rewarding agricultural scientists needs to be adjusted away from counting papers published. 3. Some examples are given of problems in poultry science which seem likely to be soluble by gene manipulation. These include “essential” amino acid synthesis within the chicken, improvement of shell strength, the prevention of many diseases, but probably not the improvement of quantitative traits or of behavioural adaptation to intensive husbandry. 4. Examples are also given of problems likely to require empirical solutions, such as the benefits of acclimatisation or the long‐term response to a lighting programme. Here the need is to develop better theories to guide modelling activities. 5. The author concludes that there is much research that can and should be done in poultry science in the next 20 years but calls for a recognition that some problems cannot be solved by a “fundamental” approach but will need experiments with whole animals coupled with model‐building activities.

Lewis, P. D.; Perry, G. C.; Morris, T. R.

doi: 10.1080/00071669608417832pmid: 8833523

Abstract 1. ISA Brown pullets were given an 8‐h photoperiod and fed ad libitum to 63 d of age. At 63 d the photoperiod was either kept at 8 h or increased to 13 h, and the photostimulated birds were subjected to 1 of 3 feeding systems: ad libitum, 8 h daily access to food or a daily individual allocation of food equal to that given to the 8 h control group. 2. Mean age at first egg (AFE) of the groups given the photoperiod increase was on average 33 d earlier than that of the 8 h controls. Within the photostimulated groups, limiting daily feeding opportunity to 8 h delayed maturity by 4 d compared with ad libitum feeding. The mean AFE of the birds which were given allocated quantities of food was intermediate and not significantly different from either of the other groups. 3. Light was the principal factor which determined AFE, but moderate food restriction had a small modifying influence, consistent with earlier evidence. 4. The 3 groups given a 5‐h increase in photoperiod consumed similar quantities of food to first egg, which was laid around 15 weeks of age. The 8 h control group ate a similar amount of food to this age, but needed more than 40% extra food to reach their first egg at 20 weeks.

Kannan, G.; Mench, J. A.

doi: 10.1080/00071669608417833pmid: 8833524

Abstract 1. Experiments were conducted to determine whether different handling methods and crating periods differentially affect plasma corticosterone (CS) concentrations in 6 to 7‐week‐old broilers. 2. Broilers were subjected to 1 of 3 handling methods for 2 min: (i) 3 birds held in an inverted position in one hand (multiple inverted, MI), (ii) 1 bird held in an inverted position (single inverted, SI), or (iii) upright handling (U), which consisted of holding a bird gently with both hands in an upright position. 3. In experiment 1 birds were returned to their respective pens after handling and in experiment 2 they were crated for up to 4 h after the imposition of handling. In experiment 2 food deprived (FD) and fully fed (FF) uncrated birds were also sampled as controls. Blood samples were collected immediately after handling and at 1‐h intervals after handling or handling and crating. 4. In experiment 1, MI and SI birds had higher CS concentrations than U birds. 5. In experiment 2, there were no significant differences in CS concentrations of crated birds despite the different handling treatments. FD birds had higher mean CS concentrations than FF birds, although not as high as those of crated birds. CS concentrations peaked at 3 h after crating. Birds showed predominantly resting behaviour after crating. 6. These results suggest that handling stress can be reduced in broilers by the use of upright handling. However, the methods of handling is not important in influencing CS concentrations if the birds are crated after handling, either because crating is a more potent stressor than handling or due to stressor additivity.

Jones, R. B.; Satterlee, D. G.; Moreau, J.; Waddington, D.

doi: 10.1080/00071669608417834pmid: 8833525

Abstract 1. Fear‐related behaviour was measured in individually‐housed Japanese quail which had received either untreated drinking water (UDW) or a vitamin C solution (ascorbyl‐2‐polyphosphate, APP, 1 g L‐ascorbic acid/1) for 1 or 4 d. Behavioural tests were carried out at 24 or 27 d of age. Water consumption was measured daily and plasma ascorbic acid (AA) content was assayed after differential treatment for 1 or 4 d. 2. The quail in the APP treatment groups drank significantly more than did those receiving untreated drinking water. 3. Supplementation with APP raised plasma AA concentrations substantially above those found in UDW quail. The lower AA concentrations found after APP treatment for 4 d rather than one may have reflected either inter‐assay variation or limited intestinal absorption following excess ingestion. 4. Quail treated with APP showed less home‐cage avoidance of a novel object and shorter tonic immobility fear reactions than did the UDW birds. The UDW quail showed remarkably similar avoidance and TI scores on test days 1 and 4. Conversely, continued treatment with APP further reduced avoidance scores but, although TI durations fell slightly with continued treatment there were no significant day effects. 5. It was concluded that APP supplementation can reduce underlying fearfulness but that it may not be necessary to continue treatment for longer than 24 h immediately prior to a known frightening event.

Yahav, S.; Straschnow, A.; Plavnik, I.; Hurwitz, S.

doi: 10.1080/00071669608417835pmid: 8833526

Abstract 1. Male broiler chickens were exposed in separate experiments to: (a) constant ambient temperatures (Ta) ranging between 10 and 35°C; (b) 12 h: 12 h diurnal high‐low temperature of 10:30°C, 15:35°G and 15:30°C in different trials; and (c) 12 h of 30 or 35°G and 12 h of variable lower temperature. 2. A progressive decline in weight gain and food intake was obtained as Ta increased from 18 to 35°C. Under diurnally cycling temperature, weight gain and food intake were lower than in the average corresponding constant temperature, with the exception of chickens exposed to 15:30°C, where weight gain and food intake were not significandy different from those of the constant average temperature. 3. As the diurnal cold period was made colder, chickens exposed during half of the diurnal cycle to high temperature (30, 35°C) demonstrated a significant (P ≤ 0.05) increase in weight gain and food intake. 4. There was a good correlation between plasma triiodothyronine (T3) and Ta. The correlation between T3 and food intake was highly significant, but that between T3 and weight gain was poor. 5. The results indicate the difficulties in predicting the performance of broilers exposed to diurnally cycling temperatures from knowledge of the average temperature.

Boshouwers, F. M. G.; Davelaar, F. G.; Landman, W. J. M.; Nicaise, E.; Van den Bos, J.

doi: 10.1080/00071669608417836pmid: 8833527

Abstract 1. The temperature in the close vicinity of commercial broilers was studied in relation to the setpoint temperature throughout the rearing period. 2. Mean temperature in the immediate environment of the chicks was 2.0°C lower than the setpoint of 1 d of age. During the first week this initial temperature difference gradually rose to 1.7°C above setpoint. At 18 d of age a further rise to a mean difference of 4.0°C above setpoint was measured. The difference then remained constant from 32 d of age until the end of the fattening period. 3. It was concluded that the chickens were actually brooded at 30°C. During the rearing period the ambient temperature in the close vicinity of the broilers gradually declined to 26°C. 4. During the finishing period, ambient temperature around the broilers was far above the value recommended for optimal food intake and growth. 5. These results are discussed in relation to heat generation and heat fluxes in the broiler houses.

Uni, Z.; Noy, Y.; Sklan, D.

doi: 10.1080/00071669608417837pmid: 8833528

Abstract 1. Intestinal development was examined in Arbor Acres and Lohmann chicks from one week before hatching until one week after. Changes in morphology and concentrations of DNA, RNA and protein in the duodenal tissue were determined. 2. Villus height and perimeter increased 9 to 11 fold from day 14 of incubation until 7 d after hatching. Arbor Acres chicks had values which were consistently higher than Lohmann chicks. 3. DNA concentration of duodenal tissue increased with age in parallel to the increase in the number of enterocytes per villus. In the pre‐hatch period tissue activity as indicated by RNA/DNA, and ribosomal capacity as shown by the RNA/protein ratios, were high for both strains; values for Arbor Acres embryos and chicks were greater than for Lohmann. 4. DNA concentrations, RNA/DNA, RNA/protein and protein/DNA ratios correlate with morphological measurements and can be used as additional criteria for evaluating development in chick intestine. 5. In the last week of incubation and immediately after hatching, intestinal growth appears to arise mainly from cellular hyperplasia and not from cellular hypertrophy. Intestinal development patterns were similar for both strains but growth was more rapid in Arbor Acres chicks.

Brown, C. R.; Peinke, D.; Loveridge, A.

doi: 10.1080/00071669608417838pmid: 8833529

Abstract 1. The ostrich industry in South Africa (and elsewhere) experiences a high rate of embryo mortality during artificial incubation of eggs. Most of this mortality takes place in the last 10–14 d of incubation. 2. We carried out post‐mortem examinations on 111 embryos that died within this period to assess the causes of this mortality. 3. Malpositioning and severe oedema were the predominant symptoms of dead‐in‐shell embryos with 55% being malpositioned and 41% showing severe oedema. Of these, 22 embryos (24%) showed both symptoms. Malpositioning generally results from incorrect setting of the eggs or inadequate turning and oedema was significantly correlated with the amount of water lost from the eggs which in turn was correlated with egg size. 4. Myopathy, gross lesions of internal organs, haemorrhage, bacterial infections and congenital deformities were found in less than 10% of chicks examined for these symptoms.

Davis, R. H.; Fear, J.; Winton, A. C.

doi: 10.1080/00071669608417839pmid: 8833530

Abstract 1. Diets containing supplements of selenium (10 mg/kg as sodium selenite), copper (500 mg/kg as copper (II) sulphate) and sodium nitroprusside (SNP 300 mg/kg) as a source of cyanide, were fed singly and in all possible combinations to chicks from 14 to 35 d of age. 2. Both copper and SNP individually alleviated the growth depression caused by excess selenium but interacted adversely with one another. The effect of SNP was to decrease liver selenium but copper increased it. Despite this contrast it is suggested that both achieve their beneficial effects through influences on the fraction of liver selenium that can be reduced to volatile forms by hydrochloric acid and zinc. 3. In a second experiment the effects of diets containing additional selenium (2 mg/kg as sodium selenite or selenomethionine) with or without additional copper (100 mg/kg) or SNP (100 mg/kg) on selenium incorporation into eggs were compared. 4. SNP reduced incorporation from selenite whereas copper had no effect. However, copper reduced the incorporation from selenomethionine into the protein fractions of egg white as much as SNP.

Ravindran, V.; Sivakanesan, R.

doi: 10.1080/00071669608417840pmid: 8833531

Abstract 1. The nutrient composition of sweet potato tuber meal (SPM) was similar to that of maize, with the exceptions of crude protein and calcium. The crude protein content was lower (62 v 91 g/kg) and the calcium content was higher (1–9 v 0–1 g/kg) in SPM. The amino acid composition, in general, favoured SPM. 2. Trypsin inhibitor activity, and the contents of oxalate and phytate‐phosphorus in SPM were too low to be of any nutritional concern. 3. The apparent metabolisable energy content of SPM was determined to be similar to that of maize (14–51 v 14–45 MJ/kg). 4. The results of feeding trials showed that SPM can replace up to 400 g/kg maize in broiler diets without adverse effects in performance. The depression in weight gains observed in birds fed on a diet containing 600 g SPM/kg was related largely to lowered food intake arising from the powdery texture of SPM.