The influence of pelleted feed on the response of growing pullets to photoperiods of less than ten hours

Abstract

Abstract 1. An experiment was designed to test the hypothesis that delayed sexual maturity in pullets reared on very short (4 h) constant photoperiods might be partly attributable to limitation of food intake and that offering a pelleted feed might circumvent this effect. 2. The factors investigated were 2 strains (Amber Link and Hyline Brown), 3 photoperiods (4, 7 and 10 h) and 2 forms of food (mash throughout rearing or crumbs from 0 to 4 weeks followed by pellets). All 12 combinations of these factors were tested with 14 replications of 18 pullet chicks allocated to each combination. 3. Mean ages at first egg for 4, 7 and 10 h rearing photoperiods were 189, 184 and 162 d respectively. Pullets given the pelleted diet ate 2% less food to 20 weeks but were 6% heavier at that age. However, the pellet-fed birds were 6 d later in mean age at 50% lay. There was no interaction between form of food and photoperiod in the data for age at first egg. 4. It is concluded that constant short photoperiods during rearing cause delayed sexual maturity entirely due to the effect of light on gonadal development and that limitation of food intake is not a factor in this response.