Abstract:
Three experiments were conducted to examine the effects of self-select feeding to 40 weeks of age on food, protein and metabolizable energy (ME) intakes and egg mass output of pullets previously trained to this feeding system between 15 and 19 weeks of age and kept at cool (10�_-20�_C) and hot (25�_-35�_C) temperatures. In two experiments different lighting patterns were also compared without noticeable effect. Except for ME intake on the low-ME diet in Experiment 2, protein and ME intakes were significantly improved when pullets fed a low-ME (10.2 MJ/kg) or high-ME (12.0 MJ/kg) complete layer diet at both temperatures were offered a separate protein concentrate on a self-select basis. Increases in egg mass output were most pronounced when the high-ME complete diet was fed with the protein concentrate at the hot temperatures. The resulting egg mass output was similar to that obtained when the low-ME complete diet was fed with the protein concentrate or when a highly concentrated, complete diet, based on the intakes of the high-ME diet and the separate protein concentrate selected by pullets of similar age in an earlier study, was fed. Providing a separate granular source of calcium had no significant effect on the responses to self-select feeding.