Genetic variation and phenotypic correlations of food consumption of laying hens corrected for body weight and production.

1. On samples from two brown-egg strains between 1967 and 1979, "residual" food consumption (i.e. food consumption corrected for body weight, weight change and egg mass) of laying hens was investigated with respect to variation between sire families and phenotypic correlations with production traits, egg traits, morphological and physiological variables. A similar residual food intake (corrected for body weight and body-weight gain) was obtained for samples of males in some years. 2. Highly significant differences between sire families were observed for residual food consumption in both strains for females and in one strain for males. 3. In females, highly significant positive phenotypic correlations were found in both populations for residual food intake with wattle length and shank temperature, and in one population with shank length and width. On the whole, a negative correlation was observed with egg-shell thickness. For two variables recorded only in one strain, proportion of broken eggs yolk: albumen ratio, there were highly significant positive correlations. 4. For males also, wattle length and shank temperature were positively correlated with residual food intake. 5. The physiological meaning and possible use of correlated variables as criteria for indirect selection for food efficiency of layers are discussed.