Patterns of body condition use and its impact on fertility

Abstract

A total of 60 nulliparous crossbred rabbit females were, a posteriori, divided into 2 experimental groups according to their natural "decision" to conceive or not at day 11 post first parturition (L: solely-lactating or LP: lactating-pregnant). This design allowed us to study the evolution of body reserves around first parturition and its influence on the future reproductive success of rabbit females. Primiparous rabbit females that failed to conceive when inseminated at day 11 post-partum (L) seemed to have a higher perirenal fat thickness (PFT) 12 d pre-partum (+0.25 mm; P=0.079) than females that conceived (LP). In the subsequent days, L females showed a significantly higher mobilisation rate than LP females (on av.-0.12 and -0.07 mm of PFT per day, respectively; P=0.007), reaching a lower PFT at partum (5.17 mm vs. 5.62 mm, respectively; P = 0.002). However, due to a greater recovery rate observed in L females (+0.15 vs. +0.08 mm of PFT per day for L and LP females, respectively; P=0.007), PFT at 10 d post-partum was similar (on av. 5.86 mm). These different patterns showed that PFT level at 12 d pre-partum and PFT mobilisation rate onwards seems to drive the start of a new pregnancy. It also seems to modify the energy metabolism of rabbit females, allowing does to recover perirenal fat tissue without compromising the production of milk necessary for the current litter.