Research Note: Interaction between hatching time and chick pull time affects broiler live performance

This study investigated the effects of broiler chick hatching time and pull time on subsequent live performance. Hatching eggs were obtained from commercial broiler breeder flocks of Ross 308 at 29 and 30 wk of age in trials 1 and 2, respectively. Eggs were incubated in 2 identical setters on 2 consecutive days. In both trials, portion of the eggs (9,600), incubated on the first day of set, were assigned to delayed-pull (DP) treatment, and the other portion of the eggs (9,600), incubated on the second day of set, were assigned to normal-pull (NP) treatment. The hatching period was divided into 3 hatching time groups, and chicks were classified as hatching in the early (478 to 490 h), middle (490 to 496 h), or late period (496 to 510 h of incubation). At 510 h of incubation based on the NP set date, all chicks were transferred to a broiler research house. A total of 7,200 and 8,400 chicks within 2 chick pull time treatments × 3 hatching time groups were raised in trials 1 and 2, respectively. The primary difference between the DP and NP treatments was an additional 24 h holding period in the hatcher for the DP group. Therefore, chick BW was higher at placement in the NP treatment than in the DP treatment (P < 0.001). However, this advantage disappeared by 7 d, and the average BW did not differ between the DP and NP treatments at 41 d. Chick pull time did not affect feed consumption or feed conversion ratio (FCR) at 41 d. Similar to pull time, hatching time did not impact BW, feed consumption or FCR at 41 d. However, for mortality and European Production Efficiency Index (EPEI) at 41 d, a hatching time × pull time interaction was observed (P < 0.001). Mortality was higher and EPEI was lower in late hatch chicks than in chicks hatched early and middle in the NP treatment, whereas for chicks in the DP treatment, mortality and EPEI did not differ among the hatching time groups. These data indicated that the DP treatment, which held the chicks for an additional 24 h in the hatcher under optimum conditions, produced a lower initial BW accompanied by a period of compensatory weight gain through 41 d, and no differences (P > 0.05) in live performance occurred due to the holding time in the hatcher. Overall, sending the late hatched chicks to the broiler house shortly after hatching increased their mortality and negatively affected their live performance (as measured by EPEI), unlike holding early hatched chicks for a relatively long time after hatching (50 h) in the hatcher.