Correlated responses on growth traits after two-stage selection for ovulation rate and litter size in rabbits

Abstract

Rabbit commercial maternal lines are usually selected for litter size (LS) and paternal lines for growth rate (GR). Line OR_LS was selected by ovulation rate (OR) and LS to improve LS more efficiently. In this study, growth traits of line OR_LS were evaluated by estimating the correlated response on weaning weight (WW), slaughter weight (SW) and GR during fattening period as well as their variability (DWW, DSW and DGR, respectively). Data were analyzed using Bayesian inference methods. Heritability estimates were low for growth traits (0.09, 0.13 and 0.14 for WW, SW and GR, respectively) and negligible for growth traits variability (0.01, 0.004 and 0.01 for DWW, DSW and DGR, respectively). Moderate common litter effect ratio (c2; 0.35, 0.28 and 0.27) and low maternal effect ratio (m2; 0.11, 0.05 and 0.01) were obtained for WW, SW and GR, respectively. Both c2 and m2 were lower at slaughter than at weaning. In addition, low common litter effect and negligible maternal effect were observed for growth traits variability. Genetic correlations between LS and both growth traits and their variability were close to zero. Positive genetic correlations were observed between OR and growth traits (0.19, 0.38 and 0.36 for WW, SW and GR, respectively) as well as between OR and growth traits variability (0.35, 0.62 and 0.20 for DWW, DSW and DGR, respectively). Positive correlated responses in both periods were obtained for growth traits, WW, SW and GR (0.037, 0.156 and 0.110 kg, respectively). The correlated response found in growth traits might be due to the positive genetic correlations between OR and these traits. However, selection for OR and LS using independent culling levels did not modify the growth traits variability. Therefore, no negative consequences on growth traits can be expected in current commercial maternal lines.

Litter Survival Differences between Divergently Selected Lines for Environmental Sensitivity in Rabbits

“…This has implications for animal welfare, since animals that cope better with their environment have better welfare than more sensitive animals [7]. After correcting for litter size, both lines had similar individual weight at birth, and survival at birth and survival at 4 days of age were [15].…”

Genomic analysis of divergently selected experimental lines in rabbit

“…Regarding the reproductive traits, they present low-to-moderate genetic correlations with growth traits in pigs (Holm et al, 2004;Skovsted et al, 2005; Rothschild and Ruvinsky, 2011), minks (Karimi et al, 2018), mice (Malik, 1984), rats (Eisen, 1976), rabbits (Garreau et al, 2004;Peiró et al, 2019) and all polytocous species. In rabbits, estimations of genetic correlations amongst reproductive traits and body weight traits within lines were low (Garcıá and Baselga, 2002;Peiró et al, 2019) or inconsistent (Camacho and Baselga, 1990), since studies suggested positive and negative correlations between them (Camacho and Baselga, 1990;Bünger et al, 2005). For instance, genetic correlations between litter size and weaning weight, slaughter weight, and growth rate were -0.11, 0.03 and 0.11, respectively (Peiró et al, 2019).…”

“…In rabbits, estimations of genetic correlations amongst reproductive traits and body weight traits within lines were low (Garcıá and Baselga, 2002;Peiró et al, 2019) or inconsistent (Camacho and Baselga, 1990), since studies suggested positive and negative correlations between them (Camacho and Baselga, 1990;Bünger et al, 2005). For instance, genetic correlations between litter size and weaning weight, slaughter weight, and growth rate were -0.11, 0.03 and 0.11, respectively (Peiró et al, 2019). Garcıá & Baselga (2002) found very low genetic correlation (0.06) between ADG and litter size.…”

“…Garcıá & Baselga (2002) found very low genetic correlation (0.06) between ADG and litter size. Furthermore, correlated responses have been null-to-low for growth and carcass traits in experiments of litter size selection in pigs (Estany et al, 2002;Petry et al, 2004) and rabbits (Garcıá and Baselga, 2002;Peiró et al, 2019).…”

“…"Divergent selection for uterine capacity in rabbits." Journal of Animal Science, 75 (9): 2350-2354 Badawy, A. Y., R. Peiró, A. Blasco, and M. A. Santacreu, 2019…”