Evaluation of milk yield and some related maternal traits in a crossbreeding project of Egyptian Gabali breed with Spanish V-line in rabbits.

This study was conducted in a four-year rabbit project that aimed to develop a synthetic line named Moshtohor (M) by crossing Sinai Gabali breed (G) with the Spanish V-line (V). The G, V, F(1) (G x V), F(2) (G x V)(2) and M line were analysed. Traits of doe body weight at delivery (DBW), litter size at birth (LSB) and at weaning (LSW), milk production during the first, second, third and fourth week of lactation and total milk yield (TMY) were recorded. Data were analysed using a repeatability uni-trait animal model to estimate the genetic parameters and estimable functions of genetic group effects. Based on them and the matrix of their variance-covariance, the crossbreeding parameters were also estimated. Estimates of heritabilities for all the studied traits were low ranging from 0.06 to 0.11 for DBW, LSB and LSW and from 0.0 to 0.06 for milk production traits. Permanent environmental effects were very low ranging from 0.0 to 0.10 for all the traits, except for DBW (0.41). Least square means of V line were superior (p < 0.05) in DBW (3253 versus 3037 g) and LSB (6.71 versus 6.28 young) relative to G breed. M line had superiority in LSB (6.94 young) compared with G breed. M line and G breed were better than V line for milk production traits (3415 and 3236 versus 2893 g for TMY). Significant effects of direct additive were observed for most traits studied (ranged from -6.8 to 20.7%). Effects of individual heterosis for most milk production traits were significant and ranged from 2.1 to 13.9%, but they were not significant for DBW, LSB and LSW. On the opposite side, effects of maternal heterosis for all the traits were not significant.