Dietary energy level, feeder space, and group size on growth performance and carcass characteristics of growing-finishing barrows and gilts

To benefit from feeding low net energy (NE) diets, growing-finishing pigs must be able to increase feed intake to compensate for lower caloric density, but this might be difficult in pens with a high stocking density. Access to the feeder, trough space, and(or) floor area may limit voluntary feed intake. The objective of this study was to clarify the relationships among dietary NE level, feeder space, group size, sex, and interactions in growing-finishing pigs. In a 2 × 2 × 2 × 2 factorial design, 1920 pigs (33 kg) housed in 96 fully-slatted floor pens (6.1 × 2.4 m) with 2 or 3 feeder spaces, and 18 or 22 barrows or gilts per pen, were fed either low (9.2 MJ/kg) or high (9.85 MJ/kg) NE diets over 5 growth phases (Grower 1: day [d] 0 to 20, Grower 2: d 21 to 41, Grower 3: d 42 to 62, Finisher 1: d 63 to 80, Finisher 2: d 81 to slaughter). Pen body weight (BW) and average daily feed disappearance (ADFD) were measured for each growth phase, biweekly from the start of shipping and at slaughter. Warm carcasses were weighed and graded (Destron). For the entire trial, pigs fed low versus (vs.) high NE diets had 0.119 kg/d greater (P < 0.001) ADFD, but 0.556 MJ/d lower (P < 0.050) average daily caloric disappearance (ADCD), and 0.017 kg/kg lower (P < 0.001) gain-to-feed (G:F). Pens with 18 vs. 22 pigs had 0.062 kg/d greater (P < 0.001) ADFD, 0.730 MJ/d greater (P < 0.010) ADCD, and 0.029 kg/d greater (P < 0.001) average daily weight gain (ADWG). Pigs in pens with 3 vs. 2 feeding spaces had 0.051 kg/d greater (P < 0.010) ADFD, 0.511 MJ/d greater (P = 0.050) ADCD but 0.004 kg/kg lower (P < 0.050) G:F. Pigs fed low vs. high NE diets had 0.6 kg lower (P < 0.050) carcass weight and 0.9 mm lower (P < 0.050) loin depth. Pens with 18 vs. 22 pigs took 2.8 days less (P < 0.001) to reach 130 kg slaughter BW. Pens with 18 vs. 22 pigs had a 0.4 %-point decrease (P < 0.050) in dressing percentage. Feeding low vs. high NE diets reduced (P < 0.001) feed cost by Can $21.87/tonne, $3.34/pig, $0.03/kg gain, and increased (P < 0.05) gross income subtracting feed cost (ISFC) by $1.82/pig. Housing 18 vs. 22 pigs per pen increased (P < 0.010) ISFC by $1.98 per pig. Lack of interactions between NE level, feeder space, and group size for ADFD indicate that low NE diets can be fed to pigs even if they have lower than recommended floor area allowance during part of the finishing phase.

THE EFFECTS OF STOCKING DENSITY ON THE PERFORMANCE OF BROILER CHICKENS

THREE trials were conducted to determine the optimum stocking density for broiler chickens raised in a tropical environment In Trial 1, 100,67, 50,40, 34 and 29 birds were placed in duplicates in each pen with an area of 3.72 M2 to give stocking densities of 0.037, 0.056, 0.074, 0.093, 0.10 and 0 128 M2 per bird respectively. In Trial 2, stocking densities of 0.046, 0056, 0.064, 0.074, 0.083 and 0.093 M2 per bird were compared. Trial 3 involved studying the effects of providing equal feeder space (5cm/bird) or equal number of similar sized feeders (2 feeders per pen) when birds were stocked at floor spaces of 0.056, 0.064, 0.74, 0.083 and 0.093 sq meter per bird. Results showed that weight gain and feed consumption decreased, while total meat yield and net income per unit area increased, with increase in stocking rates. Feed efficiency, mortality and carcass dressing percentages were not significantly affected by the stocking rates. The effects of stocking densities on the performance of the birds were not altered by equalizing the feeder space per bird or by providing equal number of feeders per unit space. Management problems in terms of wetness of litter, feeding and watering were encountered with stocking densities of 0.037, 0.046 and 0.056 M2/ bird. Stocking rates of 0.083, 0.093, 0.10 and 0.128 M2 were uneconomic and did not produce superior performances to stocking densities of 0.064 or 0.074 M2/bird. On the basis of the results, floor spaces of 0.064 or 0.074 M2 per bird may be recommended as the optimum for broiler chickens raised in the tropics. The feeder space at these optimum stocking rates need not be more than 5cm per bird.

Breakdown of the ideal free distribution under conditions of severe and low competition

Under the ideal free distribution (IFD), the number of organisms competing for a resource at different sites is proportional to the resource distribution among sites. The ideal free distribution of competitors in a heterogeneous environment often predicts habitat matching, where the relative number of individuals using any two patches matches the relative availability of resources in those same two patches. If a resource is scarce, access might be restricted to individuals with high resource holding potential, resulting in deviation from the IFD. The distribution of animals may also deviate from the IFD in the case of resource abundance, when social attraction or preference for specific locations rather than competition may determine distribution. While it was originally developed to explain habitat choice, we apply the habitat matching rule to microscale foraging decisions. We show that chickens feeding from two nondepleting feeders distribute proportionally to feeder space under intermediate levels of competition. However, chicken distribution between the feeders deviates from the IFD when feeder space is limited and competition high. Further, despite decreasing aggression with increasing feeder space, deviation from IFD is also observed under an excess supply of feeder space, indicating different mechanisms responsible for deviations from the IFD. Besides demonstrating IFD sensitivity to competition, these findings highlight IFD’s potential as a biological basis for determining minimal resource requirements in animal housing. Significance statement The ideal free distribution (IFD) predicts how animals ought to distribute themselves within a habitat in order to maximize their payoff. Recent studies, however, have questioned the validity of the IFD concept following anomalous results. We studied the IFD in chickens by systematically varying the amount and distribution of space at two feed troughs. We show that when tested over a sufficiently large range, the distribution of birds depends on the overall resource availability. Furthermore, behavioral data suggest that distinctly different mechanisms account for deviations from the IFD at shortage and excess supply of feeder space, respectively.

Research Brief: Effect of Feed Form andFeeder Position on Feed Consumption Patterns in Male Broilers

Highlights Male broilers showed significant preference for whole pellets as compared to a 50:50 (by mass) mixture of pellets and fines and 100% fines. Broilers preferentially consumed pellets from the mixed diets, with 65% of the mixed diet consumed as pellets. Changes in feeder location did not affect preferences, and locations of preferred feed forms were readily re-acquired after re-positioning. Variation in pellet content may reduce effective feeder space through increased competition for pellets. Abstract. Post-starter phase broiler diets are almost universally pelleted during the manufacturing process to improve nutrient density, handling characteristics, and live performance. Low pellet durability, transportation, and on-farm handling and distribution can result in pellet destruction, ultimately resulting in variation in pellet distribution in a wire-auger feeding system. Given that poultry selectively feed to meet nutritional needs, the variation in pellet distribution observed in commercial feeding systems may result in a reduction in effective feeder space through increased competition for pellets. The objective of this study was to determine the effect of mixtures of feed form and location on feed consumption patterns in broilers. Feed form treatments included 100% pellets (P), a 50:50 mix (M) of pellets and fines (by mass), and 100% fines (F). A total of 264 broilers were randomly allocated to each of six rooms at 37 days of age and provided with each of the three feed form treatments in separate feeders. Feeder locations were rotated every three days, allowing each feed form treatment to be located in all three feeder positions. Overall mean consumption rates for each feed form treatment were significantly different (p = 0.0001) with 70.3%, 21.3%, and 8.1% for the pellet only, mixed, and fines diets, respectively, and a pooled SEM of 0.02%. No significant differences were found for feeder position (p = 0.12) or test period (p = 0.91). Broilers were able to reliably re-acquire the position of preferred feed form treatments after each location change Keywords: Feeding systems, Housing design, Poultry.

168 Effects of proportion of pigs per feeder hole and stocking density on growth performance and tail and ear biting in the nursery

The objective of this study was to evaluate the impact of different numbers of pigs per feeder hole and stocking densities on growth performance and incidence of tail and ear biting in the nursery. A total of 2,160 pigs (PIC 337 × Camborough, initial BW 6.1 ± 0.3 kg; weaning age 21.5 ± 0.7 d) were used in a 42-d study. Each pen contained a semi-automatic feeder with 2, 4, 6, or 8 holes of 16 cm wide by 14 cm deep each. At allotment, 20 pigs were placed per pen. The experiment was designed in a 4 x 3 factorial arrangement with nine replicates per treatment, comparing four different number of pigs per feeder hole (PFH) (10; 5; 3.3 and 2.5), and three stocking densities (SD) (0.15; 0.25 and 0.35 m2/pig). Pen was the experimental unit for data analysis. For final weight and ADG, a quadratic effect (P = 0.001) was observed for PFH and linear effect (P = 0.001) for SD. For ADFI, low stocking density increased ADFI (linear, P = 0.002). For G:F, a quadratic effect was observed for PFH (P = 0.037). No significant effects were observed for mortality (P > 0.464). The percentage of removals was affected by the interaction between PFH and SD (P = 0.039), indicating that increasing feeder space may reduce the percentage of removals at high stocking densities (0.15 and 0.25 m2/pig). For tail and ear biting, a quadratic effect was observed for PFH and SD (P = 0.031). These results suggest that both feeder space and stocking density affect performance and incidence of tail and ear biting, most of the times as quadratic and linear effects, respectively, and the factors may work together to influence pig removal rate in the nursery phase.

355 Effect of shelf setting of a wet/dry feeder on growth performance of finishing pigs

Recent advancements in wet/dry shelf feeders have caused them to become more popular in swine finishing barns. Pigs consume feed faster from wet/dry feeders compared with dry feeders, so manufacturers recommend higher stocking density than dry feeders. However, there are little data published indicating optimal feeder shelf settings for wet/dry feeders. The objective of this study was to evaluate two shelf settings for wet/dry feeders in a commercial setting. Pigs (n = 1200) were blocked by initial BW and pens were assigned within block to one of two shelf settings: 60% or 85% open. Openings for each feeder were determined by caliper measurement. Each pen (n = 20/treatment) was stocked with 30 pigs, providing 2.54 cm of linear feeder space (15 pigs per 38.1 cm feeder hole) and 0.637 m2 of floor space per pig. Mash feed (primarily corn-soybean meal-DDGS) delivery was recorded daily using Big Dutchmen Feed Exact Pro, and pigs were weighed biweekly throughout the 84 d trial. Data were analyzed using PROC MIXED of SAS with pen considered the experimental unit. Initial pig BW was similar (17.5 vs 17.4 kg; SE=0.1) for 85% and 60% treatments, respectively. Feeder shelves that were 85% open allowed pigs to have greater (P < 0.01) ADG (1.06 vs. 1.02 kg/d; SE=0.01), ADFI (2.63 vs. 2.48; SE=0.01) and were heavier at d 84 (107.1 vs 103.3 kg; SE=0.4) compared with feeder shelf openings of 60%. However, feeders that were 60% open supported better G:F (0.412 vs 0.404; P < 0.01; SE=0.001) compared with the 85% openings, respectively. No behavioral vices were observed in this study. These data suggest shelf settings for wet/dry feeders that are 85% open support faster but less efficient growth than shelf settings of 60%.