Genetic differences in turnover of glycogen phosphorylase in broiler and layer chickens.

Specific labelling of glycogen phosphorylase with the precursor of the cofactor has allowed definition of the turnover parameters of the enzyme in the pectoralis of rapidly growing broiler chickens, and slowly growing layer chickens. Selection for rapid growth rate in broilers has resulted in a lower rate of turnover of phosphorylase, but the difference between rates of synthesis and degradation is maintained, which contrasts markedly with the age-dependent coalescence of the two values in layer chickens.