A total of 5,240 body weight records of quail of offsprings from 200 males and 400 females matings, fed crude protein diet levels varying from 24 to 30% and 2,900kcal of metabolizable energy, was used to evaluate the sensitivity of genetic values of two meat strains, EV1 and EV2, to changes in crude protein levels of diets, using random regression models. Quails showing higher body weight genetic value in the average environment (crude protein level equal to zero in a scale varying from -1 to 1) respond positively to an increase in crude protein level of diet, this change is more important for EV2 quails (higher slope) and of small magnitude for EV1 quails at 21 days of age. EV1 quails at 42 days of age showed remarked increase in the dispersion for breeding values as crude protein level increased in the diets, suggesting heterogeneity of slope of the breeding values to change in protein level of diets or suggesting a genotype x protein level of diet interaction. EV2 quails showed an increase in the breeding values in function of crude protein level of diet for both ages. Genotype x protein level of diet interferes earlier in the phenotype expression of EV2 quails. Heritability estimates showed a sizeable variation and were of higher values for quails fed higher protein level diets, except for EV1 quails at 21 days of age. Genetic evaluations of quails fed specific crude protein level do not allow a prediction of valid breeding values for quails fed other crude protein level of diet.
meat-type quail; reaction norm; genotype x environment interaction
