HERITABILITY OF MILK YIELD IN A POPULATION OF RABBITS UNDER THE CONDITIONS OF THE VALLEY OF MEXICO

Abstract

Variance components and heritability of milk production were estimated for a population of 114 does (42 New Zealand White (NZW), 24 Californian (CAL), 37 NZW x CAL, and 37 CAL x NZW) in the Mexican Valley. Does were daughters of 21 sires and 53 dams which included 300 litters and 2375 milk yield records. Milk yield (MY) was calculated weighing each litter 8 times, before and after milking. Statistical analysis was carried out by using an individual animal model, which included the fixed effects of breed group, kidding number (1, 2, 3), number of nipples (8, 9, 10), kidding month (January-February, March-April, May-June, July-August), pregnant state (pregnant does and empty does), the covariates days of lactation, days of pregnancy and litter size, and the direct and residual random effects. The mean and standard deviation for MY was 145±64 gd-1. The additive genetic variance, the error variances phenotypic variance and the heritability of MY were 247.86 g2, 1869.0 g2 and 0.12±0.02, respectively. In conclusion, the heritability of milk production was low, but within the range of values notified in the literature; which suggest that genetic selection might not be best choice for improving milk yield in rabbits.