Demographic history, current status, and efficiency of the mating strategy were analyzed using the pedigree of Pannon White (PW) rabbits born between 1992 and 2007. Potential accumulation of detrimental effects and loss of genetic diversity were also considered. Calculations and estimates were done most often for rabbits born in 2007, whereas other reference populations (REFPOPXXXX) were specified explicitly. The pedigree contained 4,749 individuals and 580 founders, and its completeness was 82.1% up to 10 and 94.5% up to 5 generations, respectively. Generation intervals through different pathways averaged 1.2 yr. When adjusted to the pedigree completeness, the amount of inbreeding (F(i)) of rabbits was comparable (5.54%) with that of other livestock populations, whereas the 10 (30) founders contributing the most to inbreeding explained a large part of the population inbreeding [i.e., 42.24% (73.18%)]. The ancestral inbreeding coefficient of REFPOP2004 (10.67%) was one-half that of REFPOP2007 (20.66%), showing its strong dependence on pedigree length. Family variance, inbreeding, and realized effective population size were 84.18 (REFPOP2006; this variable could not be calculated for the last year examined), 37.19, and 91.08, respectively. The effective numbers of ancestors, founders, and founder genomes were 48, 26, and 7.33, respectively. Although the circular mating scheme applied was generally effective, the large accumulated reduction in genetic variability indicates the need to revise and improve the current breeding strategy.

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In this study, the rabbit breeding programme conducted at the Kaposvár University is extensively discussed. Population history and recorded traits, creation of the different synthetic lines, evolution of their selection criteria, estimation of the genetic parameters and genetic trends are the main elements described. The programme (Pannon rabbit breeding programme) is operated with 1 maternal line and 2 paternal lines. At present the maternal line (Pannon Ka) is selected for number of kits born alive, while the 2 paternal lines are pre-selected for litter weight (Pannon White) and average daily gain (Pannon terminal line), respectively, then they are both selected for thigh muscle volume (based on computer tomography (CT) measurements). All these traits are evaluated by BLUP methodology. According to the genetic parameter estimations, the heritability of the reproductive traits (litter size and litter weight) was low (0.05-0.17 and 0.08-0.17). When the litter size component traits were extended with dominance effects, the magnitude of the dominance components varied between 0.05 and 0.08. Average daily gain and thigh muscle volume were moderately heritable (0.21-0.27 and 0.19-0.25), while heritability estimates of the carcass traits (dressing out percentage and hind part ratio) were high (0.47 and 0.59). Computer tomography based traits showed favourable high genetic correlations with the carcass traits (dressing out percentage: 0.45-0.47 and hind part ratio: 0.59). On the contrary, strong negative correlation was estimated between thigh muscle volume and litter weight (-0.37 and -0.70). The selection responses obtained for all analysed traits were within the range published by the relevant literature. The success of the CT-based selection for improving meat production was justified by different methods (crossing experiment, divergent selection, estimated genetic trends). In addition to the slow increase in the inbreeding level of the Pannon White breed, it also proves the effectiveness of the circular mating scheme used in all three rabbit breeds in the programme.

Abstract. Genetic parameters, inbreeding depression and genetic trends were estimated for average daily gain between the ages of 5-10 weeks and thigh muscle volume (measured in vivo with computerized tomography) in a group of 22 098 Pannon terminal line rabbits born between 2006 and 2011 and reared in 3 396 litters. The data sets were analysed with bi-variate animal models taking pedigree completeness (complete generation equivalent) into account. By 2011, all rabbits were inbred and the average inbreeding coefficient and complete generation equivalent of the population were 7.69 % and 11.89 %, respectively. Estimated heritability was moderate both for average daily gain (0.23±0.02) and thigh muscle volume (0.25±0.03). Litter effects were low for both traits (0.16±0.00 and 0.09±0.01 respectively). The genetic correlation coefficient estimate between average daily gain and thigh muscle volume was also low (0.02±0.08). Significant inbreeding depression (per 10 % inbreeding) was only detected for average daily gain (0.57 g/d). The estimated annual selection response was substantial both for average daily gain and thigh muscle volume (1.49 g/d and 5.84 cm3, respectively), proving the efficiency of the breeding programme.

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).