The enhancement of rabbit female functional longevity, that is the ability to avoid
voluntary culling, is a paramount aspect for the sustainability of meat rabbit production;
this trait represents a direct indicator of female robustness. The objective
of our study was to compare the functional longevity of five rabbit lines at their
foundation and at fixed times during their selection processes. Four of them are maternal
lines (A, V, H and LP) selected for litter size at weaning. The fifth line is the
paternal line R, founded and selected for post-weaning
daily gain from 28 to 63 days.
The comparison at foundation involved the complete data set (from March 1980 to
March 2013; records of 15,670 does) and pedigree (19,405 animals). Latter comparisons
were made when all lines shared the same environmental and management
conditions, from March 1997 to September 1998 and from March 2011 to September
2012. In these second comparisons, the same model as that used in the comparison
at foundation was used, but now the additive effect was excluded, only data from
the corresponding periods were considered. At their foundation, lines V, H and LP
showed larger functional longevity than lines A and R, being LP line that with the
longest productive life. In the latter comparisons, lines A and R still showing the lowest
functional longevities. However, as the selection process evolves, the differences
between these two lines and the others were reduced. It could be concluded that the
average longevity of a population greatly depends on the criteria followed for its
foundation. In addition, along the selection for litter size, the differences of longevity
between lines tend to decrease, this is due to an unintended selection for functional
longevity, since only offspring from females reaching three parturitions are selected
as breeding animals for the next generation. |
