Post-pellet liquid application fat disproportionately coats fines and affects mixed-sex broiler live performance from 16 to 42 d of age

Post-pellet liquid application fat disproportionately coats fines and affects mixed-sex broiler... Abstract The effect of 2 fat application sites (FAS) and 2 levels of fines on feed manufacturing parameters and broiler live performance from 16 to 42 d was studied. The FAS included mixer-added fat (MAF) and post-pellet liquid application (PPLA) of fat. While the MAF diets had all fat added to the diet prior to pelleting, the PPLA diets were pelleted with 0.5% MAF, and the remaining 3.5% fat was added subsequent to pellet cooling. The levels of fines included 0 and 30%. A total of 32 pens was placed with 8 males and 8 females (mixed-sex) in each pen. Broiler chicks were fed a common crumbled starter for approximately 16 d and then transitioned to one of the 4 dietary treatments. The PPLA pellets were more durable than were MAF pellets (P < 0.01), but required more energy to pellet (P < 0.01). When adding liquid fat post pellet to the diets with 30% fines, the fines absorbed more liquid fat and exhibited a greater gross energy when compared to pellets (P < 0.01). Male broilers consuming the PPLA diets were 50, 97, and 120 g heavier than male broilers consuming the MAF diets at 28, 35, and 42 d, respectively (P < 0.01). Female broilers consuming the PPLA diets with 30% fines were 71 and 90 g heavier than female broilers consuming the MAF diets with 30% fines at 28 and 35 d, respectively (P < 0.05). It was concluded that the females may have benefited from consuming high-energy-density fines present in the PPLA diets with 30% fines when compared to females consuming MAF diets with 30% fines because the additional fat that coated the fines offset the negative energy associated with prehension of the fines. DESCRIPTION OF PROBLEM Feed represents the greatest monetary input for animal producers. It has been estimated that 60 to 70% of the cost of animal production is dedicated to feed ingredients and their transformation into an edible form [1]. It has been reported that the greatest expenditure in the manufacture of broiler feeds is the pelleting process, which has been shown to represent over 40% of the energy consumed in a feed mill [2]. Despite the expense of pelleting, it has long been understood that offering broilers pelleted feeds has resulted in improved live performance. Specifically, research has shown that broilers offered pellets consumed feed more efficiently than broilers consuming mash, resulting in less time spent at the feeder [3]. Once the benefits of pellets to broiler live performance was established, a need existed to determine how pellet quality affected broiler live performance, with pellet quality having been defined as the ratio of pellets to pellet fines in the feeder [4]. It was demonstrated that offering broilers diets with an increasing level of fines resulted in decreased BW gain and poorer FCR [4]. It was concluded that fines exhibited a lower effective energy density because the energy required to consume the feed was greater. Several factors have been determined to affect pellet quality, including diet ingredient composition, conditioning parameters, particle size, pellet mill die specifications, and pellet cooling [5]. Of all the factors affecting pellet quality, diet ingredient composition has been determined to be the most influential. Mixer-added fat (MAF) has been shown to be detrimental to pellet quality [6–10], but as fat is an essential ingredient that provides broilers with dietary energy, compromises between dietary energy and pellet quality have long been required. Post-pellet liquid application (PPLA) systems were implemented to solve this conflict. Utilizing PPLA systems allows liquid fat to be withheld from the mixer before pelleting, and then added post pellet so that pellet quality is maintained while still using liquid fats. However, even though the quantity of liquid fat can be reduced prior to pelleting, the generation of fines during the production process is inevitable. Considering the generation of fines throughout the process and the use of PPLA systems, it was proposed that liquid fat could preferentially coat fines when compared to pellets, since fines exhibited a greater surface-area-to-mass ratio. Previous work also has determined that fines retained less moisture than pellets after cooling, which could result in liquid fat exhibiting greater affinity for fines because their hydrophobic forces would be weakened relative to higher-moisture pellets [11]. With the above in mind, it was theorized that post-coating fat, in the presence of fines, could lead to an imbalance of energy density across the feed forms, which could affect live performance given preferential consumption of pellets over fines. MATERIALS AND METHODS Feed Manufacturing The experimental methods utilized 2 fat application sites (FAS) and 2 levels of fines to make corn-soy-based broiler diets (Table 1). The fat addition was either MAF or PPLA. The targeted levels of fines were 0 and 30%. All feed was manufactured following the guidelines for Current Good Manufacturing Practice (CGMP). All corn and soybean meal was ground using a hammermill [12] equipped with a 2.4 mm screen on the impact side and a 3.2 mm screen on the release side. The grower and finisher basal diets were batched and then blended in a twin shaft counterpoise ribbon mixer [13] for 180 s of dry mix time, and then an additional 90 s of wet mix time. The basal diets contained 0.5% MAF. The PPLA diets were pelleted as the basal, while the MAF diets were blended with an additional 3.5% MAF for an additional 90 s of mix time prior to pelleting. The diets were conditioned for 30 s at 79°C for the grower diets and 74°C for the finisher diets in a single-pass conditioner [14] and then pelleted using a 30 HP pellet mill [15]. The pellet mill was equipped with a 4.4 × 28.5 mm die for the common starter diet and a 4.4 × 44 mm die for the grower and finisher diets. Pellets were cooled in a counterflow cooler [16]. The starter diet was crumbled [17], while the grower and finisher diets remained in pellet form. The grower and finisher diets were screened [18] to ensure 100% pellets were available to generate the 0% fines diets. Any material that passed a US # 6 screen was considered to be fine and used to generate the 30% fines diets. Table 1. Ingredient composition of broiler starter, grower, and finisher diets. Ingredients  Starter (0 to 15 d)  Grower (16 to 34 d)  Finisher (35 to 42 d)    (%)  Corn  60.85  61.94  66.91  SBM (48% CP)  29.35  28.54  24.76  Poultry fat  1.00  4.00  4.00  Poultry byproduct meal  5.58  2.00  1.00  Limestone  0.60  0.64  0.60  Dicalcium phosphate  1.15  1.45  1.33  Salt  0.50  0.50  0.50  DL-Methionine  0.20  0.19  0.15  L-Lysine  0.14  0.11  0.13  L-Threonine  0.08  0.08  0.07  Trace mineral premix1  0.20  0.20  0.20  Vitamin premix2  0.05  0.05  0.05  Choline chloride (60%)  0.20  0.20  0.20  Selenium3  0.05  0.05  0.05  Coccidiostat4  0.05  0.05  0.05  Calculated nutrients        Protein  22.25  20.00  18.00  Calcium  0.90  0.80  0.70  Available phosphorous  0.45  0.40  0.35  Total lysine  1.25  1.12  1.01  Total methionine + cysteine  0.91  0.82  0.73  ME, kcal/g  2.94  3.09  3.15  Ingredients  Starter (0 to 15 d)  Grower (16 to 34 d)  Finisher (35 to 42 d)    (%)  Corn  60.85  61.94  66.91  SBM (48% CP)  29.35  28.54  24.76  Poultry fat  1.00  4.00  4.00  Poultry byproduct meal  5.58  2.00  1.00  Limestone  0.60  0.64  0.60  Dicalcium phosphate  1.15  1.45  1.33  Salt  0.50  0.50  0.50  DL-Methionine  0.20  0.19  0.15  L-Lysine  0.14  0.11  0.13  L-Threonine  0.08  0.08  0.07  Trace mineral premix1  0.20  0.20  0.20  Vitamin premix2  0.05  0.05  0.05  Choline chloride (60%)  0.20  0.20  0.20  Selenium3  0.05  0.05  0.05  Coccidiostat4  0.05  0.05  0.05  Calculated nutrients        Protein  22.25  20.00  18.00  Calcium  0.90  0.80  0.70  Available phosphorous  0.45  0.40  0.35  Total lysine  1.25  1.12  1.01  Total methionine + cysteine  0.91  0.82  0.73  ME, kcal/g  2.94  3.09  3.15  1Mineral premix provided the following per kg of diet: Mn, 120 mg; Zn, 120 mg; Fe, 80 mg; Cu, 10 mg; I, 2.5 mg; Co, 1 mg. 2Vitamin premix provided the following per kg of diet: vitamin A, 6600 IU; vitamin D3, 1980 IU; vitamin E, 33 IU; vitamin B12, 0.02 mg; biotin, 0.13 mg, menadione, 2 mg; thiamine, 2 mg; riboflavin, 6.6 mg; pantothenic acid, 11 mg; vitamin B6, 4 mg; niacin, 55 mg; folic acid, 1.1 mg. 3Selenium premix provided Se at 0.3 mg/kg of feed. 4Monensin was included at 99 mg/kg of feed (Coban 90, Elanco, Greenfield, IN). View Large The basal diets were batched and stored in overhead bins. Equal allotments of each basal batch were used to batch the PPLA and MAF diets. After sufficient pellets were collected, the remaining pellets were crumbled [17] to generate fines. The MAF-0% fines diets were made by bagging screened pellets directly out of the pellet storage bin. The rest of the diets required additional mixing beyond pelleting to add required amounts of fat or fines. The additional mixing occurred in a single-shaft double-ribbon mixer [19]. The MAF-30% fines diets were made by combining 70% screened pellets with 30% fines in the mixer where they were subjected to 10 s of mixing time. The PPLA-0% fines diets were made by combining 96.5% screened pellets with 3.5% fat where they were subjected to 70 s of mixing time. The PPLA-30% fines diets were made by combining 67.5% screened pellets and 29% fines with 3.5% fat that were then subjected to 70 s of mixing time. The purpose of mixing pellets and fines with fat was to mimic poor pellet quality entering a PPLA system, even though a PPLA system was not specifically employed for feed manufacture during the current trial. Broiler Management The Institutional Animal Care and Use Committee (IACUC) approved all bird handling and housing. The rearing of broilers occurred in a fully enclosed tunnel-ventilated broiler house with PVC and wire pens on concrete floors covered with wood shavings. A total of 32 1.2 × 1.8 m pens was used, allotting 8 replicate pens per dietary treatment. Each pen contained one bell-type drinker and one tube feeder. The litter in each pen was from a previous study that used a common diet for all pens. The caked litter was left unaltered to reduce broiler intake of shavings. A total of 256 Ross YPM × 708 males and 256 Ross YPM × 708 females were allocated to one of 4 dietary treatments to provide 8 males and 8 females in each pen [20]. Chicks were sourced from the resident university broiler breeder flock. Equal placement of males and females in each pen (mixed-sex) better represented current industry practices in which broilers have been generally placed straight-run. Each chick was introduced to water and placed on feed upon entering its pen. Each chick was allotted 908 g of common starter crumble before transitioning to its respective dietary treatments at approximately 16 d of age. Each tube feeder was shaken daily from 7 d of age. After 14 d, each tube feeder was shaken twice daily. Feed was adjusted at 14 d for any mortality to ensure all birds were allowed access to the same amount of starter feed prior to transitioning to treatment grower diets. Feed also was adjusted at 35 d for any mortality to ensure all birds were allowed access to 2.7 kg of their respective grower diets. The finisher diets were fed from approximately 35 d through the remainder of the trial. The lighting schedule was 23 h of light to 7 d, 22 h to 14 d, 21 h to 21 d, and 16 h thereafter. The litter brooding temperatures were 36°C at placement then incrementally decreased to 29°C by 7 days. The temperature remained constant at 28°C to 14 d, 26°C to 21 d, and was then maintained to 24°C through 42 days. Data Collection Feed manufacturing data collection included production rates, conditioned mash and hot pellet temperatures, pellet samples for pellet durability analysis, and pellet mill energy consumption. Pellets were subjected to pellet durability testing via the standard and modified [21] tumble box method. Samples of pellets and fines were analyzed for gross energy [22] and crude fat [23]. Pellet mill energy consumption was collected by the feed mill automation system as a continuous input variable at the programmable logic controller every 15 s [24]. Live performance data collection included male and female group BW at placement, 14 d, 28 d, 35 d, and 42 days. Feed weighbacks were collected at 14 d, 28 d, 35 d, and 42 days. The BW and feed weighback data were used to calculate feed intake (FI) and adjusted FCR. The FCR was calculated based on BW gain from hatch and was adjusted by adding the BW of any mortality from each pen into the FCR equation. Statistical Analysis The feed manufacturing data were analyzed using the Fit Model platform of JMP 11.2 [25] as a one-way ANOVA based on FAS. The gross energy and crude fat of the diets were analyzed using the Fit Model platform of JMP 11.2 as a one-way ANOVA based on FAS, level of fines, and feed form. The live performance experiment was a 2 × 2 factorial design with 2 FAS and 2 levels of fines. Live performance data were analyzed as a completely randomized block design using the Fit Model platform of JMP 11.2 for ANOVA. Means were separated with the LSMeans procedure of JMP and considered statistically significant at P ≤ 0.05 unless otherwise noted. RESULTS AND DISCUSSION Feed Manufacturing It was determined that the 30% fines treatments, regardless of FAS, were not statistically different in the actual level of fines. This was also true for the 0% fines treatments, which verified the mixing procedures implemented to maintain equal amounts of fines. The PPLA pellets were more durable than the MAF pellets utilizing the standard and modified tumble box method in both the grower and the finisher diets (P < 0.01). The PPLA pellets also required more energy to pellet and gained more heat as they transitioned through the pellet mill die hole wall when compared to the MAF pellets (P < 0.01) (Table 2). This was in agreement with previous data that demonstrated the negative impact that MAF had on pellet durability [6–10]. A similar trend was reported in which energy consumption decreased as the percentage fat added at the mixer increased [6]. This occurred because the fat acted as a lubricant between the feed and the pellet mill die hole wall, which reduced the pressure within the die [26]. Since more energy was invested during pelleting the PPLA diets, a greater amount of heat was transferred into the feed as it passed through the pellet mill die hole wall. This was in agreement with other reports suggesting that compounds with the inherent ability to reduce energy input at the pellet mill also reduced the amount of heat transferred to the pellets transitioning the die [27]. Removing MAF reduced the lubricious value of the feed, which resulted in an increased hot pellet temperature. Table 2. Effect of fat application site (FAS) on pellet durability as determined by the standard (PDI) and modified (MPDI) tumble box methods, pellet mill energy consumption (PMEC), and change in temperature between conditioned mash and hot pellets in grower and finisher diets.     Grower  Finisher  FAS1  n  PDI2  MPDI3  PMEC4  ΔT5  PDI  MPDI  PMEC  ΔT      (%)  (%)  (kWh/T)  (°C)  (%)  (%)  (kWh/T)  (°C)  MAF  3  90.47B  48.27B  7.89B  5.83b  90.73B  55.13B  8.66B  7.83B  PPLA  3  95.27A  81.27A  10.85A  10.17a  94.53A  78.93A  12.34A  13.72A   P-value  0.002  0.001  0.001  0.013  0.001  0.001  0.001  0.001   SEM6  0.49  2.32  0.27  0.714  0.31  1.17  0.19  0.303      Grower  Finisher  FAS1  n  PDI2  MPDI3  PMEC4  ΔT5  PDI  MPDI  PMEC  ΔT      (%)  (%)  (kWh/T)  (°C)  (%)  (%)  (kWh/T)  (°C)  MAF  3  90.47B  48.27B  7.89B  5.83b  90.73B  55.13B  8.66B  7.83B  PPLA  3  95.27A  81.27A  10.85A  10.17a  94.53A  78.93A  12.34A  13.72A   P-value  0.002  0.001  0.001  0.013  0.001  0.001  0.001  0.001   SEM6  0.49  2.32  0.27  0.714  0.31  1.17  0.19  0.303  a,bMeans within each column that possess different superscripts differ significantly (P ≤ 0.05). A,BMeans within each column that possess different superscripts differ significantly (P ≤ 0.01). 1Fat application site included 4% mixer-added fat (MAF) or 0.5% mixer-added fat with the additional 3.5% fat added post pellet (PPLA). 2Pellet Durability Index (ASAE S269.4) was determined on samples collected at the pellet mill die. 3Pellet Durability Index (ASAE S269.4) was determined on samples collected at the pellet mill die with 3 nuts (diameter = 19 mm). 4Pellet mill energy consumption was collected as a continuous variable by automation system. 5Change in temperature was determined between conditioned mash exiting the conditioner and hot pellets exiting the pellet mill die. 6Standard error of mean (SEM) for n = 3 samples of each FAS. View Large Gross energy and crude fat were significantly different between pellets and fines of the PPLA diet with 30% fines in both the grower and finisher diets (P < 0.01) (Table 3). The fines exhibited greater gross energy and crude fat when compared to pellets in the grower and finisher diets. These data demonstrated that fines absorbed more liquid fat than pellets when they were post coated in the presence of each other. This most likely occurred because fines possessed a greater surface-area-to-mass ratio when compared to pellets, which would have allowed them to absorb more liquid per unit weight when compared to pellets. Table 3. Effect of fat application site (FAS) and level of fines on gross energy and crude fat analysis of pellets and fines in grower and finisher diets.         Gross energy2  Crude fat3  FAS1  Fines  Feed form  n  Grower  Finisher  Grower  Finisher    (%)      (kcal/g)  (%)  MAF  0  Pellets  3  3.84B  3.85B  5.94A,B  5.42B  PPLA  0  Pellets  3  3.91A,B  3.86B  5.81B  5.79B  PPLA  30  Pellets  3  3.87B  3.75B  4.89B  5.79B  PPLA  30  Fines  3  4.02A  4.02A  7.83A  8.01A   P-value      0.009  0.002  0.008  0.006   SEM4      0.029  0.033  0.426  0.322          Gross energy2  Crude fat3  FAS1  Fines  Feed form  n  Grower  Finisher  Grower  Finisher    (%)      (kcal/g)  (%)  MAF  0  Pellets  3  3.84B  3.85B  5.94A,B  5.42B  PPLA  0  Pellets  3  3.91A,B  3.86B  5.81B  5.79B  PPLA  30  Pellets  3  3.87B  3.75B  4.89B  5.79B  PPLA  30  Fines  3  4.02A  4.02A  7.83A  8.01A   P-value      0.009  0.002  0.008  0.006   SEM4      0.029  0.033  0.426  0.322  A,BMeans within each column that possess different superscripts differ significantly (P ≤ 0.01). 1Fat application site included 4% mixer-added fat (MAF) or 0.5% mixer-added fat with the additional 3.5% fat added post pellet (PPLA). 2Determined by bomb calorimetry [22]. 3Analyzed by Carolina Analytical Services (Bear Creek, NC 27207). 4Standard error of mean (SEM) for n = 3 samples of each combination of FAS, level of fines, and feed form analyzed. View Large Grow-out Male broilers consuming PPLA diets were significantly heavier than males consuming MAF diets at 28, 35, and 42 d (P < 0.01) (Table 4). Removing fat from diets prior to pelleting has not always resulted in improved BW [9, 10]. The current study was not in agreement with these previous studies, which generally removed MAF to improve pellet quality. Similarly, the current study removed MAF to create a durable pellet, but then a portion of the pellets was ground to intentionally create poor pellet quality in the fixed 30% fines treatments. Thus, while durable pellets have traditionally accompanied improved pellet quality, the current study generated feeds having a durable pellet but an overall poor pellet quality to determine if PPLA fat would preferentially coat pellets or fines. Table 4. Main and interaction effects of fat application site (FAS) and level of fines on cumulative body weight (BW) of male and female broilers.       Male BW    Female BW  FAS1  Fines  n  14 d  28 d  35 d  42 d    14 d  28 d  35 d  42 d    (%)            (g)          Main effects                      MAF    16  463  1657B  2475B  3325B    450  1465  2107b  2770  PPLA    16  468  1707A  2572A  3445A    452  1494  2149a  2811  P-value      0.441  0.007  0.001  0.001    0.691  0.114  0.050  0.157    0  16  458b  1675  2528  3396    446  1465  2123  2799    30  16  473a  1692  2518  3374    456  1498  2133  2781    P-value    0.048  0.336  0.645  0.457    0.139  0.132  0.637  0.532    SEM2    5  13  15  20    5  13  15  20                          Interaction Effects                      MAF  0  8  461  1665  2497  3340    450  1471a,b  2125a,b  2806  MAF  30  8  465  1648  2453  3309    449  1458b  2088b  2734  PPLA  0  8  455  1684  2560  3452    441  1459a,b  2121a,b  2793  PPLA  30  8  481  1730  2584  3439    464  1529a  2178a  2829  P-value      0.146  0.081  0.129  0.754    0.102  0.029  0.031  0.067  SEM2      7  18  22  29    7  17  21  28        Male BW    Female BW  FAS1  Fines  n  14 d  28 d  35 d  42 d    14 d  28 d  35 d  42 d    (%)            (g)          Main effects                      MAF    16  463  1657B  2475B  3325B    450  1465  2107b  2770  PPLA    16  468  1707A  2572A  3445A    452  1494  2149a  2811  P-value      0.441  0.007  0.001  0.001    0.691  0.114  0.050  0.157    0  16  458b  1675  2528  3396    446  1465  2123  2799    30  16  473a  1692  2518  3374    456  1498  2133  2781    P-value    0.048  0.336  0.645  0.457    0.139  0.132  0.637  0.532    SEM2    5  13  15  20    5  13  15  20                          Interaction Effects                      MAF  0  8  461  1665  2497  3340    450  1471a,b  2125a,b  2806  MAF  30  8  465  1648  2453  3309    449  1458b  2088b  2734  PPLA  0  8  455  1684  2560  3452    441  1459a,b  2121a,b  2793  PPLA  30  8  481  1730  2584  3439    464  1529a  2178a  2829  P-value      0.146  0.081  0.129  0.754    0.102  0.029  0.031  0.067  SEM2      7  18  22  29    7  17  21  28  a,bMeans within each column that possess different superscripts differ significantly (P ≤ 0.05). A,BMeans within each column that possess different superscripts differ significantly (P ≤ 0.01). 1Fat application site included 4% mixer-added fat (MAF) or 0.5% mixer-added fat with the additional 3.5% fat added post pellet (PPLA). 2Standard error of mean (SEM) for n = 16 pens of 16 birds for each FAS and level of fines, and n = 8 for each interaction of FAS and level of fines. View Large Female broilers were subject to an interaction between FAS and level of fines in which the females consuming the PPLA diets with 30% fines were significantly heavier than females consuming MAF diets with 30% fines at 28 and 35 d (P < 0.05) (Table 4). It was previously determined that smaller birds were less dominant and spent less time at the feeder pan [28–31] and that birds compete for resources in large groups [32]. The present management practice of shaking feeders twice daily combined with the flow of a tube feeder appeared to create a feed pan in which pellets were available to the first birds at the feeder while fines were available to the subsequent birds. Females consuming the PPLA diet with 30% fines may have been heavier than the females consuming the MAF diets with 30% fines because the fines that were post coated exhibited greater gross energy and crude fat. Fat-laden fines most likely compensated for the negative energy associated with prehension of fines [4], allowing female BW to be maintained when offered a large quantity of fines. Broilers consuming PPLA diets exhibited improved FCR at 28 (P < 0.05), 35 (P < 0.01), and 42 d (P < 0.05) when compared to broilers consuming MAF diets (Table 5). A possible reason for the improved FCR when broilers consumed PPLA diets could be gut passage rate. Studies have been conducted affirming that an increased concentration of dietary fat decreased the transit time of digesta, resulting in more time for enzymatic hydrolysis of nutrients [33, 34]. While gastrointestinal transit time was not measured in the current study, the physical location of the fat surrounding the pellet as opposed to within the pellet also could have played a role in rate of passage. Furthermore, a decrease in fat digestibility was reported when diets were subjected to heat conditioning when compared to diets that were cold pelleted [35]. The PPLA diets in the current study contained fat that was not subjected to heat, which may have increased the digestibility and nutritional quality of the fat. Table 5. Main and interaction effects of fat application site (FAS) and level of fines on feed intake and feed conversion ratio (FCR) of mixed-sex broilers.       Feed intake  FCR2  FAS1  Fines  n  14 d  28 d  35 d  42 d  14 d  28 d  35 d  42 d    (%)    (g)  (g:g)  Main effects                      MAF    16  538  2143  3306  4692  1.30  1.41a  1.47A  1.57a  PPLA    16  541  2171  3340  4726  1.30  1.40b  1.45B  1.54b  P-value      0.669  0.319  0.324  0.463  0.961  0.027  0.009  0.024    0  16  538  2145  3327  4730  1.32a  1.40  1.46  1.55    30  16  542  2168  3319  4687  1.29b  1.41  1.46  1.55    P-value    0.724  0.401  0.797  0.355  0.012  0.937  0.684  0.885    SEM3    7  19  24  32  0.012  0.005  0.006  0.007  Interaction effects                    MAF  0  8  542  2154  3333  4739  1.32  1.41  1.47  1.57  MAF  30  8  533  2131  3278  4645  1.29  1.41  1.48  1.56  PPLA  0  8  534  2136  3322  4722  1.32  1.40  1.45  1.54  PPLA  30  8  550  2205  3359  4730  1.29  1.40  1.45  1.54  P-value      0.200  0.110  0.194  0.280  0.876  0.757  0.588  0.868  SEM3      9  27  34  46  0.018  0.007  0.008  0.009        Feed intake  FCR2  FAS1  Fines  n  14 d  28 d  35 d  42 d  14 d  28 d  35 d  42 d    (%)    (g)  (g:g)  Main effects                      MAF    16  538  2143  3306  4692  1.30  1.41a  1.47A  1.57a  PPLA    16  541  2171  3340  4726  1.30  1.40b  1.45B  1.54b  P-value      0.669  0.319  0.324  0.463  0.961  0.027  0.009  0.024    0  16  538  2145  3327  4730  1.32a  1.40  1.46  1.55    30  16  542  2168  3319  4687  1.29b  1.41  1.46  1.55    P-value    0.724  0.401  0.797  0.355  0.012  0.937  0.684  0.885    SEM3    7  19  24  32  0.012  0.005  0.006  0.007  Interaction effects                    MAF  0  8  542  2154  3333  4739  1.32  1.41  1.47  1.57  MAF  30  8  533  2131  3278  4645  1.29  1.41  1.48  1.56  PPLA  0  8  534  2136  3322  4722  1.32  1.40  1.45  1.54  PPLA  30  8  550  2205  3359  4730  1.29  1.40  1.45  1.54  P-value      0.200  0.110  0.194  0.280  0.876  0.757  0.588  0.868  SEM3      9  27  34  46  0.018  0.007  0.008  0.009  a,bMeans within each column that possess different superscripts differ significantly (P ≤ 0.05). A,BMeans within each column that possess different superscripts differ significantly (P ≤ 0.01). 1Fat application site included 4% mixer-added fat (MAF) or 0.5% mixer-added fat with the additional 3.5% fat added post pellet (PPLA). 2The FCR was calculated based on BW gain from hatch and was adjusted by adding the BW of any mortality from each pen into the FCR equation. 3Standard error of mean (SEM) for n = 16 pens of 16 birds for each FAS and level of fines, and n = 8 for each interaction of FAS and level of fines. View Large CONCLUSIONS AND APPLICATIONS Adding fat post pelleting improved pellet durability, but increased pellet mill energy consumption and resulted in more frictional heat transfer to pellets as they transitioned the pellet mill die when compared to diets with greater concentrations of MAF. If pellets and fines were present when adding fat post pelleting, liquids preferentially coated fines when compared to pellets. The consumption of fat-laden, energy-dense fines may have ameliorated the negative energy associated with the consumption of fines. While disproportionate liquid distribution was beneficial in the case of liquid fat, disproportionate liquid distribution may not be of benefit when considering other liquid ingredients. Footnotes Primary Audience: Feed Manufacturers, Nutritionists REFERENCES AND NOTES 1. McKinney L. J., Behnke K. C.. 2007. Principles of feed manufacuturing: Efficient broiler operation. Kansas State University . 2. Whitehead W. K., Shupe W. L.. 1980. Energy use in broiler hatcheries and feed mills. Poult. Sci.  59: 16– 20. Google Scholar CrossRef Search ADS   3. Jensen L. S., Merrill L. H., Reddy C. V., McGinnis J.. 1962. Observations on eating patterns and rate of food passage of birds feed pelleted and unpelleted diets. Poult. Sci.  41: 1414– 1419. Google Scholar CrossRef Search ADS   4. McKinney L. J., Teeter R. G.. 2004. Predicting effective caloric value of nonnutritive facts: I. Pellet quality and II. Prediction of consequential formulation dead zones. Poult. Sci.  83: 1165– 1174. Google Scholar CrossRef Search ADS PubMed  5. Behnke K. C. 1994. Factors affecting pellet quality. Pages 44– 54 in Proc. Maryland Nutr. Conf. Feed Manuf. , College Park, MD. Maryland Feed Ind. Counc., Univ. Maryland, College Park. 6. Gehring C. K., Lilly K. G. S., Shires L. K., Beaman K. R., Loop S. A., Moritz J. S.. 2011. Increasing mixer-added fat reduces the electrical energy required for pelleting and improves exogenous enzyme efficacy for broilers. J. Appl. Poult. Res.  20: 75– 89. Google Scholar CrossRef Search ADS   7. Fahrenholz A. C. 2012. Evaluating factors affecting pellet durability and energy consumption in a pilot feed mill and comparing methods for evaluating pellet durability. PhD Diss . Kansas State Univ. Manhattan, KS. 8. Corey A. M., Wamsley K. G. S., Winowiski T. S., Moritz J. S.. Effects of calcium lignosulfonate, mixer-added fat, and feed form on feed manufacture and broiler performance. J. Appl. Poult. Res.  23: 418– 428. CrossRef Search ADS   9. Loar R. E., Wamsley K. G. S., Evans A., Moritz J. S., Corzo A.. 2014. Effects of varying conditioning temperatures and mixer-added fat on feed manufacturing efficiency, 28-to-42-day broiler performance, early skeletal effect, and true amino acid digestibility. J. Appl. Poult. Res.  23: 444– 455. Google Scholar CrossRef Search ADS   10. Auttawong S. 2015. Impact of ground corn particle size and distribution on pellet quality, liver performance of broilers, and preventriculus and gizzard weights. PhD Diss . North Carolina State University. Raleigh, NC. 11. Cutlip S. E., Hott J. M., Buchanan N. P., Rack A. L., Latshaw J. D., Moritz J. S.. 2008. The effect of steam-conditioning practices on pellet quality and growing broiler nutritional value. J. Appl. Poult. Res.  17: 249– 261. Google Scholar CrossRef Search ADS   12. Hammermill, model 1522, Roskamp Champion, Waterloo, IA. 13. Twin shaft counterpoise ribbon mixer, model TRDB126060, Hayes & Stolz, Fort Worth, TX. 14. Steam conditioner, model C18LL4/F6, California Pellet Mill, Crawfordsville, IN. 15. Pellet mill, model PM1112-2, California Pellet Mill, Crawfordsville, IN. 16. Counterflow cooler, model VK09X09KL, Geeland Counterflow USA, Inc, Orlando, FL. 17. Crumbler, model 624S, Roskamp Champion, Waterloo, IA. 18. Pellet screener, model 2x4 ROTO-SHAKER, ANDRITZ Inc., Muncy, PA. 19. Single shaft double ribbon mixer, model SRM304, Scott Equipment Company, New Prague, MN. 20. Aviagen Group, Huntsville, AL. 21. ASAE. 1997. Cubes, Pellets, and Crumbles – Definitions and Methods for Determining Density, Durability, and Moisture Content . ASAE Standard S269. 4 American Society of Agricultural and Biological Engineers, St. Joseph, MI. 22. Manual bomb calorimeter, model 2901 EB, Parr Instrument Company, Moline, IL. 23. Carolina Analytical Services, Bear Creek, NC. 24. Automation system, model 47011, Repete, Sussex, WI. 25. Statistical analysis, SAS Institute, Cary, NC. 26. Thomas M., van Vliet T., van der Poel A. F. B. 1998. Physical quality of pelleted animal feed 3. Contribution of feedstuff components. Anim. Feed Sci. Tech.  70: 59– 78. Google Scholar CrossRef Search ADS   27. Wamsley K. G. S., Moritz J. S.. 2013. Resolving poor pellet quality and maintaining amino acid digestibility in commercial turkey diet feed manufacture. J. Appl. Poult. Res.  22: 439– 446. Google Scholar CrossRef Search ADS   28. Nakaue H. S. Effect of type of feeder, feeder space, and bird density under intermittent lighting regimens with broilers. Poult. Sci . 60: 708– 712. CrossRef Search ADS   29. Quart M. D., Adams A. W.. 1982. Effects of cage design and bird density on layers. 1. Productivity, feathering and nervousness. Poult. Sci.  61: 1606– 1613. 30. Cunningham D. L., van Tienhoven A., Gvaryahu G.. 1988. Population size, cage area, and dominance rank effects on productivity and well-being of laying hens. Poult. Sci.  67: 399– 406. Google Scholar CrossRef Search ADS PubMed  31. Glover B. G., Foltz K. L., Holaskova I., Moritz J. S.. 2016. Effects of modest improvements in pellet quality and experiment pen size on broiler chicken performance. J. Appl. Poult. Res.  25: 21– 28. Google Scholar CrossRef Search ADS   32. Leone E. H., Estevez I.. 2008. Space use according to the distribution of resources and level of competition. Poult. Sci.  87: 3– 13. Google Scholar CrossRef Search ADS PubMed  33. Mateos G. G., Sell J. L.. 1981. Influence of fat and carbohydrate source on rate of food passage of semipurified diets for laying hens. Poult. Sci.  60: 2114– 2119. Google Scholar CrossRef Search ADS   34. Mateos G. G., Sell J. L., Eastwood J. A.. 1982. Rate of food passage (transit time) as influenced by level of supplemental fat. Poult. Sci.  61: 94– 100. Google Scholar CrossRef Search ADS PubMed  35. Barekatain M. R., Wu S. B., Toghyani M., Swick R. A.. 2015. Effects of grinding and pelleting condition on efficiency of full-fat canola seed for replacing supplemental oil in broiler chicken diets. Anim. Feed Sci. Tech.  207: 140– 149. Google Scholar CrossRef Search ADS   © 2017 Poultry Science Association Inc. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Applied Poultry Research Oxford University Press

Post-pellet liquid application fat disproportionately coats fines and affects mixed-sex broiler live performance from 16 to 42 d of age

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© 2017 Poultry Science Association Inc.
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Abstract

Abstract The effect of 2 fat application sites (FAS) and 2 levels of fines on feed manufacturing parameters and broiler live performance from 16 to 42 d was studied. The FAS included mixer-added fat (MAF) and post-pellet liquid application (PPLA) of fat. While the MAF diets had all fat added to the diet prior to pelleting, the PPLA diets were pelleted with 0.5% MAF, and the remaining 3.5% fat was added subsequent to pellet cooling. The levels of fines included 0 and 30%. A total of 32 pens was placed with 8 males and 8 females (mixed-sex) in each pen. Broiler chicks were fed a common crumbled starter for approximately 16 d and then transitioned to one of the 4 dietary treatments. The PPLA pellets were more durable than were MAF pellets (P < 0.01), but required more energy to pellet (P < 0.01). When adding liquid fat post pellet to the diets with 30% fines, the fines absorbed more liquid fat and exhibited a greater gross energy when compared to pellets (P < 0.01). Male broilers consuming the PPLA diets were 50, 97, and 120 g heavier than male broilers consuming the MAF diets at 28, 35, and 42 d, respectively (P < 0.01). Female broilers consuming the PPLA diets with 30% fines were 71 and 90 g heavier than female broilers consuming the MAF diets with 30% fines at 28 and 35 d, respectively (P < 0.05). It was concluded that the females may have benefited from consuming high-energy-density fines present in the PPLA diets with 30% fines when compared to females consuming MAF diets with 30% fines because the additional fat that coated the fines offset the negative energy associated with prehension of the fines. DESCRIPTION OF PROBLEM Feed represents the greatest monetary input for animal producers. It has been estimated that 60 to 70% of the cost of animal production is dedicated to feed ingredients and their transformation into an edible form [1]. It has been reported that the greatest expenditure in the manufacture of broiler feeds is the pelleting process, which has been shown to represent over 40% of the energy consumed in a feed mill [2]. Despite the expense of pelleting, it has long been understood that offering broilers pelleted feeds has resulted in improved live performance. Specifically, research has shown that broilers offered pellets consumed feed more efficiently than broilers consuming mash, resulting in less time spent at the feeder [3]. Once the benefits of pellets to broiler live performance was established, a need existed to determine how pellet quality affected broiler live performance, with pellet quality having been defined as the ratio of pellets to pellet fines in the feeder [4]. It was demonstrated that offering broilers diets with an increasing level of fines resulted in decreased BW gain and poorer FCR [4]. It was concluded that fines exhibited a lower effective energy density because the energy required to consume the feed was greater. Several factors have been determined to affect pellet quality, including diet ingredient composition, conditioning parameters, particle size, pellet mill die specifications, and pellet cooling [5]. Of all the factors affecting pellet quality, diet ingredient composition has been determined to be the most influential. Mixer-added fat (MAF) has been shown to be detrimental to pellet quality [6–10], but as fat is an essential ingredient that provides broilers with dietary energy, compromises between dietary energy and pellet quality have long been required. Post-pellet liquid application (PPLA) systems were implemented to solve this conflict. Utilizing PPLA systems allows liquid fat to be withheld from the mixer before pelleting, and then added post pellet so that pellet quality is maintained while still using liquid fats. However, even though the quantity of liquid fat can be reduced prior to pelleting, the generation of fines during the production process is inevitable. Considering the generation of fines throughout the process and the use of PPLA systems, it was proposed that liquid fat could preferentially coat fines when compared to pellets, since fines exhibited a greater surface-area-to-mass ratio. Previous work also has determined that fines retained less moisture than pellets after cooling, which could result in liquid fat exhibiting greater affinity for fines because their hydrophobic forces would be weakened relative to higher-moisture pellets [11]. With the above in mind, it was theorized that post-coating fat, in the presence of fines, could lead to an imbalance of energy density across the feed forms, which could affect live performance given preferential consumption of pellets over fines. MATERIALS AND METHODS Feed Manufacturing The experimental methods utilized 2 fat application sites (FAS) and 2 levels of fines to make corn-soy-based broiler diets (Table 1). The fat addition was either MAF or PPLA. The targeted levels of fines were 0 and 30%. All feed was manufactured following the guidelines for Current Good Manufacturing Practice (CGMP). All corn and soybean meal was ground using a hammermill [12] equipped with a 2.4 mm screen on the impact side and a 3.2 mm screen on the release side. The grower and finisher basal diets were batched and then blended in a twin shaft counterpoise ribbon mixer [13] for 180 s of dry mix time, and then an additional 90 s of wet mix time. The basal diets contained 0.5% MAF. The PPLA diets were pelleted as the basal, while the MAF diets were blended with an additional 3.5% MAF for an additional 90 s of mix time prior to pelleting. The diets were conditioned for 30 s at 79°C for the grower diets and 74°C for the finisher diets in a single-pass conditioner [14] and then pelleted using a 30 HP pellet mill [15]. The pellet mill was equipped with a 4.4 × 28.5 mm die for the common starter diet and a 4.4 × 44 mm die for the grower and finisher diets. Pellets were cooled in a counterflow cooler [16]. The starter diet was crumbled [17], while the grower and finisher diets remained in pellet form. The grower and finisher diets were screened [18] to ensure 100% pellets were available to generate the 0% fines diets. Any material that passed a US # 6 screen was considered to be fine and used to generate the 30% fines diets. Table 1. Ingredient composition of broiler starter, grower, and finisher diets. Ingredients  Starter (0 to 15 d)  Grower (16 to 34 d)  Finisher (35 to 42 d)    (%)  Corn  60.85  61.94  66.91  SBM (48% CP)  29.35  28.54  24.76  Poultry fat  1.00  4.00  4.00  Poultry byproduct meal  5.58  2.00  1.00  Limestone  0.60  0.64  0.60  Dicalcium phosphate  1.15  1.45  1.33  Salt  0.50  0.50  0.50  DL-Methionine  0.20  0.19  0.15  L-Lysine  0.14  0.11  0.13  L-Threonine  0.08  0.08  0.07  Trace mineral premix1  0.20  0.20  0.20  Vitamin premix2  0.05  0.05  0.05  Choline chloride (60%)  0.20  0.20  0.20  Selenium3  0.05  0.05  0.05  Coccidiostat4  0.05  0.05  0.05  Calculated nutrients        Protein  22.25  20.00  18.00  Calcium  0.90  0.80  0.70  Available phosphorous  0.45  0.40  0.35  Total lysine  1.25  1.12  1.01  Total methionine + cysteine  0.91  0.82  0.73  ME, kcal/g  2.94  3.09  3.15  Ingredients  Starter (0 to 15 d)  Grower (16 to 34 d)  Finisher (35 to 42 d)    (%)  Corn  60.85  61.94  66.91  SBM (48% CP)  29.35  28.54  24.76  Poultry fat  1.00  4.00  4.00  Poultry byproduct meal  5.58  2.00  1.00  Limestone  0.60  0.64  0.60  Dicalcium phosphate  1.15  1.45  1.33  Salt  0.50  0.50  0.50  DL-Methionine  0.20  0.19  0.15  L-Lysine  0.14  0.11  0.13  L-Threonine  0.08  0.08  0.07  Trace mineral premix1  0.20  0.20  0.20  Vitamin premix2  0.05  0.05  0.05  Choline chloride (60%)  0.20  0.20  0.20  Selenium3  0.05  0.05  0.05  Coccidiostat4  0.05  0.05  0.05  Calculated nutrients        Protein  22.25  20.00  18.00  Calcium  0.90  0.80  0.70  Available phosphorous  0.45  0.40  0.35  Total lysine  1.25  1.12  1.01  Total methionine + cysteine  0.91  0.82  0.73  ME, kcal/g  2.94  3.09  3.15  1Mineral premix provided the following per kg of diet: Mn, 120 mg; Zn, 120 mg; Fe, 80 mg; Cu, 10 mg; I, 2.5 mg; Co, 1 mg. 2Vitamin premix provided the following per kg of diet: vitamin A, 6600 IU; vitamin D3, 1980 IU; vitamin E, 33 IU; vitamin B12, 0.02 mg; biotin, 0.13 mg, menadione, 2 mg; thiamine, 2 mg; riboflavin, 6.6 mg; pantothenic acid, 11 mg; vitamin B6, 4 mg; niacin, 55 mg; folic acid, 1.1 mg. 3Selenium premix provided Se at 0.3 mg/kg of feed. 4Monensin was included at 99 mg/kg of feed (Coban 90, Elanco, Greenfield, IN). View Large The basal diets were batched and stored in overhead bins. Equal allotments of each basal batch were used to batch the PPLA and MAF diets. After sufficient pellets were collected, the remaining pellets were crumbled [17] to generate fines. The MAF-0% fines diets were made by bagging screened pellets directly out of the pellet storage bin. The rest of the diets required additional mixing beyond pelleting to add required amounts of fat or fines. The additional mixing occurred in a single-shaft double-ribbon mixer [19]. The MAF-30% fines diets were made by combining 70% screened pellets with 30% fines in the mixer where they were subjected to 10 s of mixing time. The PPLA-0% fines diets were made by combining 96.5% screened pellets with 3.5% fat where they were subjected to 70 s of mixing time. The PPLA-30% fines diets were made by combining 67.5% screened pellets and 29% fines with 3.5% fat that were then subjected to 70 s of mixing time. The purpose of mixing pellets and fines with fat was to mimic poor pellet quality entering a PPLA system, even though a PPLA system was not specifically employed for feed manufacture during the current trial. Broiler Management The Institutional Animal Care and Use Committee (IACUC) approved all bird handling and housing. The rearing of broilers occurred in a fully enclosed tunnel-ventilated broiler house with PVC and wire pens on concrete floors covered with wood shavings. A total of 32 1.2 × 1.8 m pens was used, allotting 8 replicate pens per dietary treatment. Each pen contained one bell-type drinker and one tube feeder. The litter in each pen was from a previous study that used a common diet for all pens. The caked litter was left unaltered to reduce broiler intake of shavings. A total of 256 Ross YPM × 708 males and 256 Ross YPM × 708 females were allocated to one of 4 dietary treatments to provide 8 males and 8 females in each pen [20]. Chicks were sourced from the resident university broiler breeder flock. Equal placement of males and females in each pen (mixed-sex) better represented current industry practices in which broilers have been generally placed straight-run. Each chick was introduced to water and placed on feed upon entering its pen. Each chick was allotted 908 g of common starter crumble before transitioning to its respective dietary treatments at approximately 16 d of age. Each tube feeder was shaken daily from 7 d of age. After 14 d, each tube feeder was shaken twice daily. Feed was adjusted at 14 d for any mortality to ensure all birds were allowed access to the same amount of starter feed prior to transitioning to treatment grower diets. Feed also was adjusted at 35 d for any mortality to ensure all birds were allowed access to 2.7 kg of their respective grower diets. The finisher diets were fed from approximately 35 d through the remainder of the trial. The lighting schedule was 23 h of light to 7 d, 22 h to 14 d, 21 h to 21 d, and 16 h thereafter. The litter brooding temperatures were 36°C at placement then incrementally decreased to 29°C by 7 days. The temperature remained constant at 28°C to 14 d, 26°C to 21 d, and was then maintained to 24°C through 42 days. Data Collection Feed manufacturing data collection included production rates, conditioned mash and hot pellet temperatures, pellet samples for pellet durability analysis, and pellet mill energy consumption. Pellets were subjected to pellet durability testing via the standard and modified [21] tumble box method. Samples of pellets and fines were analyzed for gross energy [22] and crude fat [23]. Pellet mill energy consumption was collected by the feed mill automation system as a continuous input variable at the programmable logic controller every 15 s [24]. Live performance data collection included male and female group BW at placement, 14 d, 28 d, 35 d, and 42 days. Feed weighbacks were collected at 14 d, 28 d, 35 d, and 42 days. The BW and feed weighback data were used to calculate feed intake (FI) and adjusted FCR. The FCR was calculated based on BW gain from hatch and was adjusted by adding the BW of any mortality from each pen into the FCR equation. Statistical Analysis The feed manufacturing data were analyzed using the Fit Model platform of JMP 11.2 [25] as a one-way ANOVA based on FAS. The gross energy and crude fat of the diets were analyzed using the Fit Model platform of JMP 11.2 as a one-way ANOVA based on FAS, level of fines, and feed form. The live performance experiment was a 2 × 2 factorial design with 2 FAS and 2 levels of fines. Live performance data were analyzed as a completely randomized block design using the Fit Model platform of JMP 11.2 for ANOVA. Means were separated with the LSMeans procedure of JMP and considered statistically significant at P ≤ 0.05 unless otherwise noted. RESULTS AND DISCUSSION Feed Manufacturing It was determined that the 30% fines treatments, regardless of FAS, were not statistically different in the actual level of fines. This was also true for the 0% fines treatments, which verified the mixing procedures implemented to maintain equal amounts of fines. The PPLA pellets were more durable than the MAF pellets utilizing the standard and modified tumble box method in both the grower and the finisher diets (P < 0.01). The PPLA pellets also required more energy to pellet and gained more heat as they transitioned through the pellet mill die hole wall when compared to the MAF pellets (P < 0.01) (Table 2). This was in agreement with previous data that demonstrated the negative impact that MAF had on pellet durability [6–10]. A similar trend was reported in which energy consumption decreased as the percentage fat added at the mixer increased [6]. This occurred because the fat acted as a lubricant between the feed and the pellet mill die hole wall, which reduced the pressure within the die [26]. Since more energy was invested during pelleting the PPLA diets, a greater amount of heat was transferred into the feed as it passed through the pellet mill die hole wall. This was in agreement with other reports suggesting that compounds with the inherent ability to reduce energy input at the pellet mill also reduced the amount of heat transferred to the pellets transitioning the die [27]. Removing MAF reduced the lubricious value of the feed, which resulted in an increased hot pellet temperature. Table 2. Effect of fat application site (FAS) on pellet durability as determined by the standard (PDI) and modified (MPDI) tumble box methods, pellet mill energy consumption (PMEC), and change in temperature between conditioned mash and hot pellets in grower and finisher diets.     Grower  Finisher  FAS1  n  PDI2  MPDI3  PMEC4  ΔT5  PDI  MPDI  PMEC  ΔT      (%)  (%)  (kWh/T)  (°C)  (%)  (%)  (kWh/T)  (°C)  MAF  3  90.47B  48.27B  7.89B  5.83b  90.73B  55.13B  8.66B  7.83B  PPLA  3  95.27A  81.27A  10.85A  10.17a  94.53A  78.93A  12.34A  13.72A   P-value  0.002  0.001  0.001  0.013  0.001  0.001  0.001  0.001   SEM6  0.49  2.32  0.27  0.714  0.31  1.17  0.19  0.303      Grower  Finisher  FAS1  n  PDI2  MPDI3  PMEC4  ΔT5  PDI  MPDI  PMEC  ΔT      (%)  (%)  (kWh/T)  (°C)  (%)  (%)  (kWh/T)  (°C)  MAF  3  90.47B  48.27B  7.89B  5.83b  90.73B  55.13B  8.66B  7.83B  PPLA  3  95.27A  81.27A  10.85A  10.17a  94.53A  78.93A  12.34A  13.72A   P-value  0.002  0.001  0.001  0.013  0.001  0.001  0.001  0.001   SEM6  0.49  2.32  0.27  0.714  0.31  1.17  0.19  0.303  a,bMeans within each column that possess different superscripts differ significantly (P ≤ 0.05). A,BMeans within each column that possess different superscripts differ significantly (P ≤ 0.01). 1Fat application site included 4% mixer-added fat (MAF) or 0.5% mixer-added fat with the additional 3.5% fat added post pellet (PPLA). 2Pellet Durability Index (ASAE S269.4) was determined on samples collected at the pellet mill die. 3Pellet Durability Index (ASAE S269.4) was determined on samples collected at the pellet mill die with 3 nuts (diameter = 19 mm). 4Pellet mill energy consumption was collected as a continuous variable by automation system. 5Change in temperature was determined between conditioned mash exiting the conditioner and hot pellets exiting the pellet mill die. 6Standard error of mean (SEM) for n = 3 samples of each FAS. View Large Gross energy and crude fat were significantly different between pellets and fines of the PPLA diet with 30% fines in both the grower and finisher diets (P < 0.01) (Table 3). The fines exhibited greater gross energy and crude fat when compared to pellets in the grower and finisher diets. These data demonstrated that fines absorbed more liquid fat than pellets when they were post coated in the presence of each other. This most likely occurred because fines possessed a greater surface-area-to-mass ratio when compared to pellets, which would have allowed them to absorb more liquid per unit weight when compared to pellets. Table 3. Effect of fat application site (FAS) and level of fines on gross energy and crude fat analysis of pellets and fines in grower and finisher diets.         Gross energy2  Crude fat3  FAS1  Fines  Feed form  n  Grower  Finisher  Grower  Finisher    (%)      (kcal/g)  (%)  MAF  0  Pellets  3  3.84B  3.85B  5.94A,B  5.42B  PPLA  0  Pellets  3  3.91A,B  3.86B  5.81B  5.79B  PPLA  30  Pellets  3  3.87B  3.75B  4.89B  5.79B  PPLA  30  Fines  3  4.02A  4.02A  7.83A  8.01A   P-value      0.009  0.002  0.008  0.006   SEM4      0.029  0.033  0.426  0.322          Gross energy2  Crude fat3  FAS1  Fines  Feed form  n  Grower  Finisher  Grower  Finisher    (%)      (kcal/g)  (%)  MAF  0  Pellets  3  3.84B  3.85B  5.94A,B  5.42B  PPLA  0  Pellets  3  3.91A,B  3.86B  5.81B  5.79B  PPLA  30  Pellets  3  3.87B  3.75B  4.89B  5.79B  PPLA  30  Fines  3  4.02A  4.02A  7.83A  8.01A   P-value      0.009  0.002  0.008  0.006   SEM4      0.029  0.033  0.426  0.322  A,BMeans within each column that possess different superscripts differ significantly (P ≤ 0.01). 1Fat application site included 4% mixer-added fat (MAF) or 0.5% mixer-added fat with the additional 3.5% fat added post pellet (PPLA). 2Determined by bomb calorimetry [22]. 3Analyzed by Carolina Analytical Services (Bear Creek, NC 27207). 4Standard error of mean (SEM) for n = 3 samples of each combination of FAS, level of fines, and feed form analyzed. View Large Grow-out Male broilers consuming PPLA diets were significantly heavier than males consuming MAF diets at 28, 35, and 42 d (P < 0.01) (Table 4). Removing fat from diets prior to pelleting has not always resulted in improved BW [9, 10]. The current study was not in agreement with these previous studies, which generally removed MAF to improve pellet quality. Similarly, the current study removed MAF to create a durable pellet, but then a portion of the pellets was ground to intentionally create poor pellet quality in the fixed 30% fines treatments. Thus, while durable pellets have traditionally accompanied improved pellet quality, the current study generated feeds having a durable pellet but an overall poor pellet quality to determine if PPLA fat would preferentially coat pellets or fines. Table 4. Main and interaction effects of fat application site (FAS) and level of fines on cumulative body weight (BW) of male and female broilers.       Male BW    Female BW  FAS1  Fines  n  14 d  28 d  35 d  42 d    14 d  28 d  35 d  42 d    (%)            (g)          Main effects                      MAF    16  463  1657B  2475B  3325B    450  1465  2107b  2770  PPLA    16  468  1707A  2572A  3445A    452  1494  2149a  2811  P-value      0.441  0.007  0.001  0.001    0.691  0.114  0.050  0.157    0  16  458b  1675  2528  3396    446  1465  2123  2799    30  16  473a  1692  2518  3374    456  1498  2133  2781    P-value    0.048  0.336  0.645  0.457    0.139  0.132  0.637  0.532    SEM2    5  13  15  20    5  13  15  20                          Interaction Effects                      MAF  0  8  461  1665  2497  3340    450  1471a,b  2125a,b  2806  MAF  30  8  465  1648  2453  3309    449  1458b  2088b  2734  PPLA  0  8  455  1684  2560  3452    441  1459a,b  2121a,b  2793  PPLA  30  8  481  1730  2584  3439    464  1529a  2178a  2829  P-value      0.146  0.081  0.129  0.754    0.102  0.029  0.031  0.067  SEM2      7  18  22  29    7  17  21  28        Male BW    Female BW  FAS1  Fines  n  14 d  28 d  35 d  42 d    14 d  28 d  35 d  42 d    (%)            (g)          Main effects                      MAF    16  463  1657B  2475B  3325B    450  1465  2107b  2770  PPLA    16  468  1707A  2572A  3445A    452  1494  2149a  2811  P-value      0.441  0.007  0.001  0.001    0.691  0.114  0.050  0.157    0  16  458b  1675  2528  3396    446  1465  2123  2799    30  16  473a  1692  2518  3374    456  1498  2133  2781    P-value    0.048  0.336  0.645  0.457    0.139  0.132  0.637  0.532    SEM2    5  13  15  20    5  13  15  20                          Interaction Effects                      MAF  0  8  461  1665  2497  3340    450  1471a,b  2125a,b  2806  MAF  30  8  465  1648  2453  3309    449  1458b  2088b  2734  PPLA  0  8  455  1684  2560  3452    441  1459a,b  2121a,b  2793  PPLA  30  8  481  1730  2584  3439    464  1529a  2178a  2829  P-value      0.146  0.081  0.129  0.754    0.102  0.029  0.031  0.067  SEM2      7  18  22  29    7  17  21  28  a,bMeans within each column that possess different superscripts differ significantly (P ≤ 0.05). A,BMeans within each column that possess different superscripts differ significantly (P ≤ 0.01). 1Fat application site included 4% mixer-added fat (MAF) or 0.5% mixer-added fat with the additional 3.5% fat added post pellet (PPLA). 2Standard error of mean (SEM) for n = 16 pens of 16 birds for each FAS and level of fines, and n = 8 for each interaction of FAS and level of fines. View Large Female broilers were subject to an interaction between FAS and level of fines in which the females consuming the PPLA diets with 30% fines were significantly heavier than females consuming MAF diets with 30% fines at 28 and 35 d (P < 0.05) (Table 4). It was previously determined that smaller birds were less dominant and spent less time at the feeder pan [28–31] and that birds compete for resources in large groups [32]. The present management practice of shaking feeders twice daily combined with the flow of a tube feeder appeared to create a feed pan in which pellets were available to the first birds at the feeder while fines were available to the subsequent birds. Females consuming the PPLA diet with 30% fines may have been heavier than the females consuming the MAF diets with 30% fines because the fines that were post coated exhibited greater gross energy and crude fat. Fat-laden fines most likely compensated for the negative energy associated with prehension of fines [4], allowing female BW to be maintained when offered a large quantity of fines. Broilers consuming PPLA diets exhibited improved FCR at 28 (P < 0.05), 35 (P < 0.01), and 42 d (P < 0.05) when compared to broilers consuming MAF diets (Table 5). A possible reason for the improved FCR when broilers consumed PPLA diets could be gut passage rate. Studies have been conducted affirming that an increased concentration of dietary fat decreased the transit time of digesta, resulting in more time for enzymatic hydrolysis of nutrients [33, 34]. While gastrointestinal transit time was not measured in the current study, the physical location of the fat surrounding the pellet as opposed to within the pellet also could have played a role in rate of passage. Furthermore, a decrease in fat digestibility was reported when diets were subjected to heat conditioning when compared to diets that were cold pelleted [35]. The PPLA diets in the current study contained fat that was not subjected to heat, which may have increased the digestibility and nutritional quality of the fat. Table 5. Main and interaction effects of fat application site (FAS) and level of fines on feed intake and feed conversion ratio (FCR) of mixed-sex broilers.       Feed intake  FCR2  FAS1  Fines  n  14 d  28 d  35 d  42 d  14 d  28 d  35 d  42 d    (%)    (g)  (g:g)  Main effects                      MAF    16  538  2143  3306  4692  1.30  1.41a  1.47A  1.57a  PPLA    16  541  2171  3340  4726  1.30  1.40b  1.45B  1.54b  P-value      0.669  0.319  0.324  0.463  0.961  0.027  0.009  0.024    0  16  538  2145  3327  4730  1.32a  1.40  1.46  1.55    30  16  542  2168  3319  4687  1.29b  1.41  1.46  1.55    P-value    0.724  0.401  0.797  0.355  0.012  0.937  0.684  0.885    SEM3    7  19  24  32  0.012  0.005  0.006  0.007  Interaction effects                    MAF  0  8  542  2154  3333  4739  1.32  1.41  1.47  1.57  MAF  30  8  533  2131  3278  4645  1.29  1.41  1.48  1.56  PPLA  0  8  534  2136  3322  4722  1.32  1.40  1.45  1.54  PPLA  30  8  550  2205  3359  4730  1.29  1.40  1.45  1.54  P-value      0.200  0.110  0.194  0.280  0.876  0.757  0.588  0.868  SEM3      9  27  34  46  0.018  0.007  0.008  0.009        Feed intake  FCR2  FAS1  Fines  n  14 d  28 d  35 d  42 d  14 d  28 d  35 d  42 d    (%)    (g)  (g:g)  Main effects                      MAF    16  538  2143  3306  4692  1.30  1.41a  1.47A  1.57a  PPLA    16  541  2171  3340  4726  1.30  1.40b  1.45B  1.54b  P-value      0.669  0.319  0.324  0.463  0.961  0.027  0.009  0.024    0  16  538  2145  3327  4730  1.32a  1.40  1.46  1.55    30  16  542  2168  3319  4687  1.29b  1.41  1.46  1.55    P-value    0.724  0.401  0.797  0.355  0.012  0.937  0.684  0.885    SEM3    7  19  24  32  0.012  0.005  0.006  0.007  Interaction effects                    MAF  0  8  542  2154  3333  4739  1.32  1.41  1.47  1.57  MAF  30  8  533  2131  3278  4645  1.29  1.41  1.48  1.56  PPLA  0  8  534  2136  3322  4722  1.32  1.40  1.45  1.54  PPLA  30  8  550  2205  3359  4730  1.29  1.40  1.45  1.54  P-value      0.200  0.110  0.194  0.280  0.876  0.757  0.588  0.868  SEM3      9  27  34  46  0.018  0.007  0.008  0.009  a,bMeans within each column that possess different superscripts differ significantly (P ≤ 0.05). A,BMeans within each column that possess different superscripts differ significantly (P ≤ 0.01). 1Fat application site included 4% mixer-added fat (MAF) or 0.5% mixer-added fat with the additional 3.5% fat added post pellet (PPLA). 2The FCR was calculated based on BW gain from hatch and was adjusted by adding the BW of any mortality from each pen into the FCR equation. 3Standard error of mean (SEM) for n = 16 pens of 16 birds for each FAS and level of fines, and n = 8 for each interaction of FAS and level of fines. View Large CONCLUSIONS AND APPLICATIONS Adding fat post pelleting improved pellet durability, but increased pellet mill energy consumption and resulted in more frictional heat transfer to pellets as they transitioned the pellet mill die when compared to diets with greater concentrations of MAF. If pellets and fines were present when adding fat post pelleting, liquids preferentially coated fines when compared to pellets. The consumption of fat-laden, energy-dense fines may have ameliorated the negative energy associated with the consumption of fines. While disproportionate liquid distribution was beneficial in the case of liquid fat, disproportionate liquid distribution may not be of benefit when considering other liquid ingredients. Footnotes Primary Audience: Feed Manufacturers, Nutritionists REFERENCES AND NOTES 1. McKinney L. J., Behnke K. C.. 2007. Principles of feed manufacuturing: Efficient broiler operation. Kansas State University . 2. Whitehead W. K., Shupe W. L.. 1980. Energy use in broiler hatcheries and feed mills. Poult. Sci.  59: 16– 20. Google Scholar CrossRef Search ADS   3. Jensen L. S., Merrill L. H., Reddy C. V., McGinnis J.. 1962. Observations on eating patterns and rate of food passage of birds feed pelleted and unpelleted diets. Poult. Sci.  41: 1414– 1419. Google Scholar CrossRef Search ADS   4. McKinney L. J., Teeter R. G.. 2004. 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Journal of Applied Poultry ResearchOxford University Press

Published: Mar 1, 2018

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