A diallel cross was carried out involving four maternal lines of rabbit (A, V, H and LP (L) lines). The lines considered have been selected for litter size at weaning. The objective was to determine differences in functional longevity between the genetic types involved in the experiment, trying to get indications of variation between the sixteen genetic groups. This trait was defined as the number of days between the first positive palpation and the death or culling of the doe; it represents the ability to delay involuntary culling. A total of 4141 longevity records were obtained from September 2008 to January 2011 and were analysed with the Survival kite 6.0 using a fixed effects Cox proportional hazard model. The model incorporated time-dependent factors, such as Farm-year-season, number born alive, order of positive palpation and physiological status of the female; as well as the time-independent factor of the genetic type of the doe. Lines A and H have a similar ability to avoid risk factors and they both are more sensitive to these factors than lines V and LP. The differences between crosses and its reciprocal were generally not significant. The estimated heterotic effects, average of crossbreds minus average of purebreds, showed the importance of using crossbreds between specialized lines to produce the does for intensive meat rabbit production, as the risk associated to purebreds is higher than that to crossbreds. |
