Stimulation lighting of meat-type pullets

Meat-type pullets of two strains, housed in windowless floor pens, were subjected to two stimulation lighting treatments beginning at 140 days of age. The treatments provided increases in photoperiod from 6 to 16 hr/day by either 1) 5 increases of 2 hr/day each week or 2) increases each of 2 and 1 hr/day followed by 14 increases of .5 hr/day each week. Overall, there was no significant difference due to lighting treatment in number of hatching eggs per hen housed. However, age at 50% production was 6.3 days less; percentage hen egg production was higher, 56.2 vs. 54.2; and egg weight was .8 g lower for hens of Treatment 1 vs. Treatment 2. For the strain with lower egg size, the number of additional eggs obtained for Treatment 1 was no greater than losses due to undersized eggs. For the strain with higher egg size, Treatment 1 prevented excess body weight gain and permitted earlier egg production. The merits of using rapid vs. slow stimulator lighting procedures for meat-type birds depend on the egg and body weight characteristics of the strain of hen.