Litter Survival Differences between Divergently Selected Lines for Environmental Sensitivity in Rabbits

A divergent selection experiment on environmental sensitivity was performed in rabbits. The aim was to estimate the correlated response in kit weight and survival, litter weight, and weight distance from birth to weaning. The weight distance was calculated as the absolute value of the differences between the individual value and the mean value of its litter. The relationship between the probability of survival at 4 d of age, and the weight at birth, was studied. Environmental sensitivity was measured as litter size variability. A total of 2484 kits from 127 does from the low line, and 1916 kits of 114 does from the high line of the 12th generation were weighed. Both of the lines showed similar individual and litter weights at birth and weaning, and a similar survival rate at birth, and at 4 d of age. The survival rate at weaning was higher in the low line (0.67 and 0.62; P = 0.93). The weight distance was higher at birth, but lower at weaning in the low line (47.8 g and 54.1 g; P = 0.98). When the weight at birth was high, the kits had a higher survival rate. In conclusion, selection for environmental sensitivity showed a correlated response in the kits' survival, and in the homogeneity of litter weight at weaning.