Selection for Litter Size Variability: Effect on Evolution of Body Condition

Abstract

A divergent selection experiment for litter size variability has been carried out successfully in rabbits. The aim of this work was to determine the evolution of body weight and perirenal fat thickness throughout the productive lifespan of females in the high litter size variability (H) line and the low litter size variability (L) line. The traits measured in females from both the H and L lines were body weight and perirenal fat thickness at the first mating and delivery, the second mating and delivery, and the last mating. Statistical analyses were performed using Bayesian methods. The H and L lines showed similar body weights in the first and second reproductive cycles. However, the L line exhibited higher perirenal fat thickness than the H line at the second delivery (9.19 mm vs. 9.00 mm, respectively P = 87%), despite having almost one young rabbit more at birth. At the end of reproductive life, the H line had a 4.4% higher body weight and a 3.4% higher perirenal fat thickness than the L line. In conclusion, decreasing litter size variability improves the mobilisation and management of body fat reserves in females from the second reproductive cycle.