Biochemical, physiological and production indices related to fat metabolism in the laying fowl at various stages of physiological development.

The significance of fat accumulation during physiological development of layers was studied using White Leghorn X Australorp pullets from 12 weeks of age. 2. Liver fat, carcass fat, liver weight and body weight increased markedly at the onset of sexual maturity. 3. Within the liver, the protein to DNA ratio did not alter significantly during development; glycogen was not consistently depleted by egg production. 4. Liver fat content was significantly correlated with carcass fat, liver weight and DNA concentration, and plasma total lipid and cholesterol, independent of stage of development; with body weight, liver protein, moisture, and protein to DNA ratio, excluding the period prior to commencement of sexual maturation; and with plasma phospholipid during lay. 5. Obesity was a feature of faster growing fowls which matured earlier, consumed more, utilised food less efficiently for egg production and produced fewer saleable eggs.