Analysis of factors influencing longevity of rabbit does

Effect of body fatness and selection for prolificacy on survival of rabbit does assessed using a cryopreserved control population

“…The selection for prolificacy resulted in increased litter sizes of the current generation , and the effect of selection should be considered together with the effect of litter size. Animals with zero pups born alive (all dead) at parturition showed an extremely high risk of being culled confirming earlier results in rabbits (Garreau et al, 2001;Sánchez et al, 2004) and sows (Yazdi et al, 2000b) kept under commercial conditions. In addition, there was a tendency for higher risk with increasing litter size, such that dams having litter sizes above 10 pups had twice the risk of being culled as animals with litter size below 7.…”

“…The variances for the two effects were considered the same and equal to 0.025. This value was previously estimated by Sánchez et al (2004) as the sire variance in the V line.…”

Analysis of rabbit doe longevity using a semiparametric log-Normal animal frailty model with time-dependent covariates

“…Two separate regions can be observed, before and after the first parturition, around 19 days after the first positive pregnancy test (ln(19) ≈ 2.94). The same conclusions were obtained by Sánchez et al [17], using the crude Kaplan-Meier estimator for the survival function, although in this previous work the beginning of the productive life was at the first mating.…”

“…For PS = Pregnant&Lactating, the risk associated with the different levels of BA were very low and stable. In rabbits, the pattern that risk is decreasing with increasing litter size was previously observed in [9] and [17]. Table IV shows the posterior standard deviations for the risk for all the levels of the interaction PS*BA.…”

“…They argued that this bias may be due to limitations of the Laplacian integration used to obtain the marginal posterior distribution of the genetic variance component, because of the high number of parameters to integrate out in animal models and because of the lack of relationships on the female side. It is likely that these simulation results, in combination with the larger computation time in animal models compared to sire models, have led to the domination of sire models over animal models in genetic applications [9,17,18]. Another reason may be that survival models have mainly been used to address genetic aspects of longevity of dairy cows in which the family structure ressembles that of a halfsib design to a higher extent than that of a rabbit population.…”