Effect of photoperiod duration during incubation on hatch traits, growth, and behavior of Leghorn chicks to 21 days of age.

This study determined the effects of photoperiod duration during incubation on Lohmann LSL-Lite hatch traits, growth, and behavior. Eggs (n = 1,200) were randomly assigned to one of four treatments: 0L:24D (0L), 6L:18D (6L), 12L:12D (12L), or 18L:6D (18L). Light was provided via red (641 nm) LED lamps. Data were analyzed using a one-way ANOVA in a randomized complete block design with significance declared when P < 0.05. In-ovo photoperiod did not affect embryo mortality, hatchability, or hatch window. However, 5, 10, 25, 50, 75, and 90% of the eggs hatched earlier in the 18 L treatment compared to 0 L. Male chicks in the 0 L treatment were heavier than males from 12 or 18 L. Female chicks in the 0 L treatment were heavier than females from 6, 12, or 18 L. Treatment did not affect navel closure, female body length, heterophil/lymphocyte (H/L) ratio, composite asymmetry, or relative yolk-free BW and yolk sac residue. Relative weights of liver, heart, duodenum, ileum, and cecum were heaviest under 18 L. During rearing, BW was higher in the 0 L birds compared to 6 and 18 L at 7 d, 6 and 12 L at 14 d, and 18 L at 21 d, however, flock uniformity was unaffected. No effects were observed on composite asymmetry or H/L ratio at 21 d post-hatch. At 0 d, chicks incubated under 18 L spent a higher percentage of time running and a lower percentage of time resting. At 1 d, chicks in the 18 L treatment spent more time resting, walking, and foraging than those incubated under 0 L. At 2 d, chicks in the 18 L treatment spent a lower percentage of time resting and higher percentage of time foraging compared to 0 L. By 3 d, only standing behaviour was affected with chicks in the 6 L treatment standing for a higher percentage of time than chicks in the 0 and 12 L treatments. In conclusion, the use of photoperiods during incubation impacted duration of incubation without negatively affecting the development of the embryo or pullet stress and behaviour.