Raised environmental temperature and food rationing as means of restricting growth of the replacement pullet

1. Four rearing temperature regimes (15, 20, 25, 30 degrees C) and three feeding schedules (ad libitum, restricting to the ad libitum intake of the 12th week and feeding 70% of this rate) were carried out with layer replacement pullets to 170 d of age. From this age, during lay, birds were kept at either 21 degrees C or on a 24-h cycle of 21 for 18 h and 28 degrees C for the 6 h before lights out. Both a white and a brown egg-laying strain were used. 2. Body weight at 169 d of age varied from, on average, 1409 g (15 degrees C, ad libitum) to 943 g (30 degrees C, 70% schedule) for the white strain and 1947 to 1250 g for the same treatments respectively for the brown strain. Sexual maturity was considerably delayed by the 70% feeding schedule, only slightly by rearing at 30 degrees C. 3. Rearing at 30 degrees C tended to depress subsequent egg output. The 70% feeding schedule at least maintained egg output compared with birds fed ad libitum in rearing. 4. There was a highly significant effect of temperature treatment during lay on food intake. The reduction in food intake due to the 21-28 degrees C cycle, however, appeared small.