Effects of moment of hatch and feed access on chicken development

The current study evaluated effects of hatch moment and immediate feed and water access within a 24-h hatch window on chicken growth and development. Five hundred four male chickens obtained from a 49-wk-old Ross 308 breeder flock were assigned to 72 cages based on hatching moment (early, midterm, or late; selected during periods of 475 to 481, 483 to 487, and 489 to 493 h after onset of incubation). At the end of each hatching period, chickens were moved to the grow-out facility and one-half of the chickens received feed and water ad libitum immediately. Remaining chickens received feed and water from 504 h after onset of incubation (d 0). Body weight gain and feed intake for each cage were recorded at d 0, 1, 4, 7, 11, and 18. Chickens were sampled at d 4 and 18 for organ and carcass development. Early hatchers had lower BW at placement compared with midterm and late hatchers but compensated for this afterward, resulting in a higher BW at d 4 (112.8, 107.1, and 103.3 g, respectively). From d 0 to 18, early hatchers tended to have higher BW gain than both other groups. Relative breast meat yield at d 18, expressed as percentage of carcass weight, was higher for early (30.4%) than midterm (28.5%) and late hatchers (27.8%). Up to d 7, direct feed access resulted in higher BW gain (6.1%) and feed intake (4.2%) compared with delayed feed access. No effect of moment of feed access on feed efficiency or organ weights was found. Direct feed access resulted in a higher weight:length ratio of the jejunum (12.5%) and ileum (7.5%) at d 4 compared with delayed feed access. These results suggest that early hatchers have a different developmental and growth pattern than midterm or late hatchers within a 24-h hatch window. A mild delay in feed access after hatch affects growth and development during the first week after hatch