Egg numbers, weight, and egg mass production in meat-type quail through 58 weeks old

Abstract

Egg production was evaluated in a line of meat-type quail undergoing selection for increased 21-day body weight, using random regression and compares the influence of heterogeneity of residual variance on estimated genetic parameters to the growth curve of meat quails. Six models were estimated, one for homogeneous residual variance and five for heterogeneous residual variance structures, established at intervals of 182, 112, 91, 56, or 28 days. An increase (P < 0.01) of the natural logarithm of the likelihood function, by increasing the number of heterogeneous classes was observed. The model that considered homogeneity of residual variances  was inadequate. Genetic variability was observed for egg weight with homogeneity of residual variance varying from .15 to  .32 and with heterogeneity varying from .16 to .38 in 13 partial (4-wk long) laying periods. Heritabilities for number of eggs laid and egg mass varied from .03 to .10 and .03 to .15, and from 0.01 to 0.15 and .01 to .20, respectively, with homogeneity and heterogeneity of residual variances. It is justifiable to include egg weight in the selection goals for meat-type quail. Low heritabilities values were found for egg number and egg mass but there are particular periods, especially from 99-126 days old and from 211-238 days old where selection could be effective. Peak production values for the three traits occurred between these periods.