Lack of effect of body weight of breeder pullets at various ages and the amount of food allocated on their subsequent laying performance

Abstract

1. Two factorial experiments were carried out with White Rock (Arbor Acres) female pullets, kept in layer cages, to evaluate the relationship between body weight (BW) at different ages and the amount of food allocated (FA) on laying performance. Differences in BW at the beginning of experiments 1 and 2 (12 and 18 weeks of age, respectively) were obtained by segregating pullets raised under the recommended FA into weight groups (WGs): standard (ST), light BW (LBW) and heavy BW (HBW). Each of the 3 WGs was further divided into 2 subgroups, raised either under the recommended FA or a moderately increased FA until 34 weeks of age. The experiments were terminated at approximately 65 weeks of age. 2. Body weight was significantly (P 0.05) affected by WGs until 28 and 60 weeks, and by FA until 56 and 44 weeks of age in experiments 1 and 2, respectively. The increased FA significantly accelerated the age of onset of egg production and increased BW at that time. Neither of these variables was affected by BW at 12 weeks of age. BW at 18 weeks of age did not affect age of sexual maturity, but at that time the BW of the LBW- and the HBW-birds was significantly lower and higher, respectively, than that of the ST-birds. 3. Number of eggs per laying or per housed hen was not affected by the WG and/or FA. The exception was the significant interaction between the 2 factors in their effect on the number of eggs per laying hen observed in experiment 1, in which the increased FA prevented the decline in the HBW-birds. 4. The data suggest that the laying performance of broiler breeder hens segregated according to their weight at 12 or 18 weeks of age, and kept in layer cages is not affected by their weight at these ages, and thereafter. The effects of a moderate increase in FA, and of the interaction between this factor and WGs, on laying performance, are not straightforward.