EFFECT OF PHOTOPERIOD AND LIGHT-INTENSITY ON THE PERFORMANCE OF INTACT MALE TURKEYS

Injurious pecking can be a major cause of mortality in growing turkeys , particularly if given a long photoperiod. Consequently, birds are us ually reared under low light intensity (<1 lux) and/or have their beak s trimmed. The influence of an 8, 12, 16 or 23 h photoperiod at an int ensity of 1 or 10 lux on the performance of intact (not beak trimmed o r de-snooded) BUT8 male turkeys was assessed in a 4 X 2 empirical stud y. Excessive injurious pecking in groups exposed to 10 lux light inten sity on >12 h photoperiods necessitated an unscheduled reduction to 1 lux light intensity. Overall, light intensity did not significantly af fect food intake, food conversion efficiency, growth or carcass compos ition. Groups exposed to 10 lux light intensity for all or part of the trial had higher losses and a greater incidence of pecking than birds maintained on a 1 lux light intensity. Growth was inconsistently affe cted by photoperiod, with birds on 12 h having the highest body ic,eig ht at 108 days but no significant differences at 136 days. Patterns of food intake were variable but cumulatively to 136 days food intake wa s not significantly affected by daylength. Overall, but particularly a fter 108 days, birds on longer photoperiods converted food more effici ently. Mortality and the incidence of injurious pecking was positively correlated with photoperiod and breast meat yield and testicular weig ht were greater in birds on longer daylengths. There were no significa nt interactions between photoperiod and illuminance.