Late reproductive senescence in a rabbit line hyper selected for reproductive longevity, and its association with body reserves.

The aim of the present study was to investigate differences in reproductive and body traits during successive parities between two genetic lines. The LP line was constituted by means of selection of animals having an extremely high number of parities (at least 25) and an average reproductive performance compared to the V line selected for litter size at weaning during 31 generations. The two lines were found to have an equal reproductive performance in the first three parities, but the LP line had higher reproductive performance from the fourth parturition onwards. The low reproductive performance after the third parity in the V line was suggested to be caused by constrained environmental conditions in the test station. A line by parity interaction was also observed for body weight, since body weight declined going from the third to the fourth parity in the LP line but not the V line. Thus, it was concluded that hyper selection for reproductive longevity and average prolificacy successfully delayed reproductive senescence, and that this newly founded line showed less environmental sensitivity, which might have been mediated by a higher body reserve.