Heterosis, maternal and direct genetic effects for litter performance and reproductive intervals in rabbit crosses

Abstract

A crossbreeding experiment was carried out in Egypt involving  a local breed (Baladi  Red, BR) was and an  exotic one (New Zealand effects White, and N ) to estimate direct heterosis, maternal additive effects and direct additive effects on some litter traits  and reproductive intervals in doe rabbits. Litter traits included litter size and weight and mean yourg weight (at birth, 21 days and at weaning), number bom alive and preweaning litter gain and mortality, while reproductive intervals included days open (interval from kindling to next conception) and kindling interval (period between two consecutive parturitions). Data were analysed using a linear mixed model. Winter kindlings recorded the largest litter size and the heaviest weight and gain of litter weight up to weaning along with the lowest preweaning mortality compared to autumn and spring kindlings. Heterosis was found at weaning on litter size and weight at weaning and on some interval traits but not on litter size at birth, where negative values are found. Crossbred litters obtained from mating BR bucks with NZ does were generally associated with superiority compared to those litters obtained from the reverse mating. Maternal additive effects on all letter traits were in favor of NZ breed, although the differences between the two breeds were not significant. In terms of reproductive intervals, BR-mothered litters. For all litters traits and reproductive intervals, the direct additive effect was not significant. NZ-sired litters had higher direct additive effects compared to BR-sired litters, while BR-sired litters recorded shorter reproductive intervals relative to NZ-sired litters.