Growth traits of four maternal lines of rabbits founded on different criteria: comparisons at foundation and at last periods after selection

Abstract

The objective was to compare growth traits in four maternal lines of rabbits (A, V, H and LP), with the aim of understanding the consequence of the different foundation and selection processes on the growth performance of the lines. The lines are currently in the 43th, 38th, 22th and 8th generations, respectively. Two comparisons were performed. One compared the values of the lines at their foundation, using the complete data set, the full pedigree and a two-trait analysis, including data on the selection criteria, litter size. The other comparisons were done during the last period when all the lines were housed together with the same feeding and management. The numbers of records were 323 208 for weaning weight, and 300 553 for slaughter weight and average daily Gain (from 46 708 l). The pedigree file included 346 638 animals. The second analysis used only the data corresponding to each period, and the analysis was conducted using a one-trait model. The model was the same as that defined for the comparisons at the foundation, but the additive effects were excluded. The H and LP lines showed highest values for all the traits compared. In the last periods, a good agreement was observed between the estimated differences, computed with the complete model and data set, or computed with an incomplete model and only data from the comparison period. At last periods, the differences were smaller than at foundation. The importance of the correlated response in growth after selection for litter size at weaning or the importance of a non-programmed intramating selection for the growth traits can explain the changes since foundation.

Genetic analysis of longevity in specialized lines of rabbits

“…This means that the genetic model used for the prediction of breeding values and the estimation of the differences between the lines at origin was suitable to describe this longevity data. A similar result was obtained by , when comparing reproductive traits and by Mínguez et al (2015), when comparing growth traits in the same four lines. For the paternal line R, the differences estimated using CM model did not match well those estimated using the IM model.…”

“…Unfortunately, the studies concerned with examining the effects of foundation criteria on the productive traits of maternal rabbit lines are very scarce. To my knowledge, there are only two works that studied the consequences of using different foundation criteria in four maternal rabbit lines which are selected for litter size at weaning ) dealt with doe and litter traits, and Mínguez et al, (2015) in the same lines but concerned with growth traits.…”

“…Considering that feeding costs represent about 70% of the rabbit meat production costs. The postweaning growth is a heritable trait, its heritability ranged from 0.13 to 0.48 (Rochambeau et al, 1989;McNitt and Lukefahr, 1996;Moura et al, 1997;Piles et al, 2004;Mínguez et al, 2015). In addition, this trait is less affected to common litter effects than the individual weights at specific ages Khalil and Al-Saef, 2008).…”

Optimization of Resource Allocation to the Genetic Type in Reproductive Rabbit Does

“…However, as it is difficult and expensive to obtain, animals from these lines are usually selected by postweaning daily gain (Estany et al, 1992) Sánchez et al, 2008). Therefore, there are in our institute a wide range of genetic types differing in the base population, the intensity and the criteria used during the selection process Mínguez et al, 2015).…”

“…For example, genetic correlations between growing traits and litter size are positive but low (García and Baselga, 2002;Mínguez et al, 2015).…”