Effect of Early Light Treatment and Diet Self-Selection on Laying Performance

Conventionally reared commercial strain White Leghorn type pullets subjected to a constant 8 hr day were transferred to individual laying cages at either 15, 18, or 21 weeks of age. Each treatment was represented by 10 replicate groups of 4 consecutively caged, randomly distributed birds. Fourteen hours constant light was provided throughout. Birds were offered a conventional diet or two split diets providing a diet self-selection based on calcium differential. Conventional production parameters were measured to 65 weeks of age. Age at lighting had no effect on egg weight after 26 weeks of age (P>.05), although results from egg grading at 30, 48, and 63 weeks of age showed a dramatic difference in the proportion of large and small eggs in favor of the late housed group. Mean egg weight per se was thus not a good indicator of economic egg size in this situation. After 26 weeks of age, age at lighting had no effect (P>.05) on egg production, feed intake, or shell quality. Diet self-selection resulted in improved shell quality but failed to confirm previous reports of reduced feed intake. It is concluded that in order to move very young pullets to laying quarters with immediate full light treatment, rearing treatment must necessarily be modified in order to achieve increased body weight at this earlier age.