Effect of posthatch feed and water access time on residual yolk and broiler live performance.

This study investigated the effect of feed and water access time on yolk sac utilization and subsequent broiler live performance. Hatching eggs were collected from commercial flocks of Ross 308 breeders at 35 and 39 wk of age in experiments 1 and 2, respectively. Chicks already out of their shells that still had some dampness on their down were removed, recorded, feather-sexed, and weighed at 488 h of incubation in both experiments. Chicks were weighed individually and received feed and water at 2 (immediate feed; IF), 8, 12, 16, 20, 24, 28, and 32 h after hatching (488 h) in experiments 1 and 2 (IF) and at 24, 26, 28, 32, 36, and 40 h after hatching in experiment 2. The residual yolk sac weight was determined at 32 and 40 h after hatching (day 0) in all groups in experiments 1 and 2, respectively. Feed consumption and BW were recorded at 7, 14, 21, and 35 d and at the same age relative to placement on feed and water at the end of the growing period. Mortality was recorded twice daily in both experiments. Feed and water access time did not influence yolk sac utilization in either experiment (P > 0.05). The IF group exhibited a higher (P < 0.05) BW than those that received feed at or after 28 h at 35 d in both experiments. There was a significant increase in feed consumption in the IF group compared with the groups with access to feed and water after 24 h at 35 d in experiment 2 (P < 0.05), with a similar trend in experiment 1 (P > 0.05). There were no significant differences in the feed conversion ratio (FCR) or mortality at 35 d of age, but the IF group tended to have a poorer FCR than the other groups in both experiments. When the total feed and water times were equalized among all groups, irrespective of the deprivation duration, there were no significant differences among the groups in the BW, feed consumption, the FCR, or mortality in both experiments. It can be concluded that feed and water deprivation for 28 h or longer after hatching (≥28 h) negatively affects the final BW but tends to improve the FCR at 35 d of age compared with chicks that receive feed immediately (2 h after hatching). When the feeding period was equalized in all groups, feed and water deprivation up to 40 h under optimum conditions had no detrimental effect on final live performance. These results suggest that the total feeding period is more critical for broiler performance than the time of posthatch access to feed and water.

The effect of increased concentration of carbon dioxide during the first 3 days of incubation on albumen characteristics, embryonic mortality and hatchability of broiler hatching eggs1.

Three experiments were conducted to determine the effects of increased CO2 concentration during the first 3 d of incubation on albumen height and pH, embryonic mortality, and hatchability of broiler hatching eggs. Hatching eggs were obtained from commercial broiler breeder flocks of Ross 308 at 39 and 37 wk of age in Experiments 1 and 2, respectively. In Experiment 3, eggs were collected at 28 and 35 wk of age. Eggs were incubated under either standard conditions (Control-CO2) for the entire incubation or increased CO2 concentrations during the first 3 d of incubation (High-CO2) in 3 experiments. In Experiments 1 and 2, the CO2 concentration was gradually increased from the beginning of incubation onwards to reach 0.80% at 72 h by manual injection of CO2 into airtight laboratory incubators. In the control incubators, the CO2 concentration remained below 0.10% during the same period. Prior to setting, and at 3 d of incubation, the eggs were opened for albumen height and pH measurements in Experiments 1 and 2. In Experiment 3, the eggs were set in commercial incubators. During the first 3 d of incubation, the CO2 concentration was gradually increased to reach 0.70% at 72 h naturally (High-CO2). In the Control-CO2 incubator, the CO2 concentration remained below 0.10%. After 3 d, incubation was continued with the control incubator conditions for all eggs from both groups in the 3 experiments. The albumen height was not affected by CO2 treatment, but the treatment significantly decreased albumen pH at 3 d in Experiments 1 and 2 (P < 0.05). A greater CO2 concentration during early incubation reduced fertile hatchability due to increased early embryonic mortality by 2% in the 3 experiments (P ≤ 0.05). The differences in pH might provide one explanation why increased CO2 concentration during early incubation resulted in increased early embryonic mortality. These data indicated that at the beginning of the incubation, ventilation was necessary to prevent increases in CO2 concentration for optimum hatchability results.