How to increase litter size in rabbits?
The animal article of the month for March is ‘Correlated responses on litter size traits and survival traits after two-stage selection for ovulation rate and litter size in rabbits’
Litter size is the most important economic trait in prolific species and the only selection criteria for maternal rabbit commercial lines. The number of young rabbits achieved at commercial time depends on the number of born alive as well as their post-natal survival. During the lactating period, milking and nursing ability of the doe are two essential factors. After weaning, a suitable environment to live in and an adequate diet are key features for a good growth and survival of young rabbits.
Selection for litter size has had a low success, thus alternatives have been proposed to improve it more efficiently. Ovulation rate limits the maximum number of kits that can be obtained in a litter. Litter size also depends on prenatal survival. A two-stage selection by ovulation rate and litter size is a natural way to simultaneously improve both traits. Thus, we have developed a rabbit line using this selection criterion, line OR_LS. In our experiment, females with the highest ovulation rate were selected at first stage, and the females with the largest litter size among them were selected in a second stage (Figure 1).
Figure 1: Two-stage selection by ovulation rate and litter size.
The current paper tackles the genetic evaluation of litter size at birth (number of kits born alive and dead), at 28 days-old (weaning) and at 63 days-old (commercial time) as well as their survivals after the two-stage selection experiment by ovulation rate and litter size named before. Litter size improved more using this two-stage criterion than direct selection for litter size. Several authors have suggested that increasing litter size leads to a higher mortality. However, no changes in survival at birth and from birth to commercial time were observed in this experiment. These findings support that the increase of litter size did not reduce the perinatal and postnatal survival in the LS_OR rabbit line.
This article is freely available for one month: ‘Correlated responses on litter size traits and survival traits after two-stage selection for ovulation rate and litter size in rabbits’
Author: A. Y. Badawy, R. Peiró, A. Blasco, M. A. Santacreu