Influence of the preplacement holding time and feeding hydration supplementation before placement on yolk sac utilization, the crop filling rate, feeding behavior and first-week broiler performance

Abstract

This study investigated the effects of the broiler chick preplacement holding time and feeding hydration supplementation before placement on yolk sac utilization, the crop filling rate, feeding–drinking behavior and first-wk broiler performance. Broiler hatching eggs were obtained from a commercial broiler breeder flock of Ross 308 at 37 wk of age and incubated in a commercial hatchery. At 510 h of incubation, all chicks were removed from the hatcher and separated into cardboard chick boxes containing 80 chicks each. The chick boxes were randomly separated into two groups with either added commercial hydration supplementation (gel: Hydrogel-95) or the control (no gel). Then, the chicks were randomly distributed into 5 groups with different holding times across each hydration supplementation treatment (gel and control). The preplacement holding times were 6, 24, 48, 60, and 72 h from the pull time from the hatchers in the hatchery to placement in the broiler house on the farm, at which point the chicks were able to access feed and water. There were 10 subtreatment groups comprising 5 chick preplacement holding time groups × 2 hydration supplementation groups. There were 12 replicates (160 chicks per pen) per holding period × gel treatment, with a total of 19,200 chicks placed. The feed and water access time did not influence yolk sac utilization, but the absolute or relative residual yolk sac (g, %) decreased linearly with the duration after the pull time (P < 0.001). Longer preplacement holding times were associated with a higher percentage of chicks with full crops at 3 h after placement (P < 0.001). Chicks with the shortest (6 h) preplacement holding time had a lower percentage of feed-seeking activity compared to the 24, 48, and 72 h holding time groups at 3 h after placement (P < 0.001). The highest chick eating and drinking activity was observed in the 72 h group at both 3 and 8 h after placement. Chick weight at placement was significantly reduced linearly with the duration after the pull time (0.106 g/h; R2 = 0.775), and as expected, the highest and lowest BW were found in the 6 (41.51 g) and 72 h (34.50 g) preplacement holding time groups, respectively. However, BW and BW gain were higher in the 24 h group than in the other preplacement holding time groups (P < 0.001) at 7 d after placement. Mortality within the first 3 d after placement increased only when the preplacement holding time was extended to 72 h (P = 0.002). Mortality during 4 to 7 d postplacement was not affected by the holding time at all, but the 72-h holding time group still had statistically significantly higher mortality cumulatively from 0 to 7 d (P = 0.024). Neither BW nor mortality was affected by feeding the hydration supplement at placement, and the lack of effect persisted through 7 d after placement (P > 0.05).It can be concluded that the BW at 7 d after placement was greater in the 24 h holding time group than in shorter (6 h) or longer (48, 60, and 72 h) preplacement holding time groups. In the present study, a greater number of chicks were raised, and it was clearly demonstrated that mortality, as a direct indicator of flock health and welfare, was not affected by preplacement holding times up to and including a 60 h after take-off under thermal comfort conditions, but holding for a further 12 h to 72 h, mortality at 7 d of age after placement was increased. On the other hand, holding chicks in a short period (6 h) did not improve mortality and the BW at 7 d, suggesting that some delay to placement can be beneficial. In addition, feeding hydrogel during the preplacement holding period had no positive effect on BW gain and cumulative mortality during the first week of the growing period.