Estimation of additive and dominance variance for litter size components in rabbits

Abstract

Additive, dominance, and permanent environmental variance components were estimated for the number of kits born alive, number of kits born dead, and total number of kits born of a synthetic rabbit line (called Pannon Ka). The data file consisted of 11 582 kindling records of 2620 does collected between the years 1996-2013. The total number of animals in the pedigree files was 4012. The examined traits were evaluated using single-trait and two-trait (number of kits born alive-dead) animal models containing all or part of the following effects: additive genetic effects, permanent environmental effects, dominance effects. Heritability estimates calculated using the basic single-trait and two-trait models were 0.094 ± 0.018 and 0.090 ± 0.016 for number of kits born alive, 0.037 ± 0.010 and 0.041 ± 0.012 for number of kits born dead, and 0.117 ± 0.018 for total number of kits born, respectively. The relative significance of permanent environmental effects was 0.069 ± 0.014 and 0.069 ± 0.012 for number of kits born alive, 0.025 ± 0.011 and 0.023 ± 0.010 for number of kits born dead, and 0.060 ± 0.013 for total number of kits born, respectively. Using the extended single-trait and two-trait models, the ratios of the dominance components compared to the phenotypic variances were 0.048 ± 0.008 and 0.046 ± 0.007 for number of kits born alive, 0.068 ± 0.006 and 0.065 ± 0.006 for number of kits born dead, and 0.005 ± 0.0073 for total number of kits born, respectively. Genetic correlation coefficients between number of kits born alive and number of kits born dead were 0.401 ± 0.171 and 0.521 ± 0.182, respectively. Spearman's rank correlations between the breeding values of the different single-trait models were close to unity in all traits (0.992-0.990). Much lower breeding value stability was found for two-trait models (0.384-0.898), especially for number of kits born dead. Results showed that the dominance components for number of kits born alive and number of kits born dead were not zero and affected the ranking of the animals (based on the breeding values).

Role of inbreeding depression, non‐inbred dominance deviations and random year‐season effect in genetic trends for prolificacy in closed rabbit lines

“…Contrary to us, in Nagy et al (2013Nagy et al ( , 2014, the narrow-sense heritability remained nearly unaltered irrespectively of whether dominance deviations were considered in the model or not, and narrow-sense heritability was similar or lower than dr 2 . In Nagy et al (2013Nagy et al ( , 2014, the consideration of dominance deviations improved the quality of the fit of the models. In our case, an improvement of the fit quality was never observed when adjusting dominance deviations: in the case of the A and V lines because the dominance deviations are negligible, and in the case of the H line because additive variation is nearly completely confounded with dominance variation.…”

“…In other rabbit populations (Nagy et al, 2013(Nagy et al, , 2014, also ignoring inbreeding when computing D R and fitting YS as fixed effect, estimates of the ratio of dominance variance to the phenotypic variance (dr 2 ) were of similar magnitude to our estimates for the H line. Contrary to us, in Nagy et al (2013Nagy et al ( , 2014, the narrow-sense heritability remained nearly unaltered irrespectively of whether dominance deviations were considered in the model or not, and narrow-sense heritability was similar or lower than dr 2 . In Nagy et al (2013Nagy et al ( , 2014, the consideration of dominance deviations improved the quality of the fit of the models.…”

Estimation of dominance effects for reproductive, growth and carcass traits of Pannon White rabbits

“…Nevertheless, in this study it was only observed when dominance replaced other random effects. Apart from earlier studies (Nagy et al, 2013b;2014) where relatively small dominance effects (0.05-0.08) were reported for litter size traits there are Nagy et al (2014) for different litter size composite traits in Pannon White and in Pannon White Large rabbits using single trait models. However, Nagy et al (2014) also analyzed two trait models including dominance and, in that case, the observed breeding values stability substantially decreased (0.38-0.79).…”

Analysis of the impact of cytoplasmic and mitochondrial inheritance on litter size and carcass in rabbits

“…The DNA was extracted from 31 (27 and 4 from maternal lineages 1-2) PK, 25 (1, 1, 4, 14, 4 and 1 from maternal lineages 1-6) PL and 22 (2, 1, 12 and 7 from maternal lineages) PW blood samples using commercially available NucleoSpin Blood Kit according to manufacturer's protocol (Macherey-Nagel GmbH & Co. KG, Germany). A 332-base pairs (bp) fragment of the mitochondrial D-loop region was amplified by polymerase chain reaction (PCR) using forward (5'-CACCATCAGCACCCAAAG-3') (Melo-Ferreira et al, 2009) and reverse primers (5'-ATTTAAGAGGAACGTGTGGG-3') (Pierpaoli et al, 1999). PCRs were performed in a 25 μL volume containing 0.2 μM of each primer and using Emerald AMP GT PCR Master Mix (Takara Bio Inc, Japan) according to the manufacturer's protocol.…”