Effect of inbreeding on lean meat percentage and average daily gain in Hungarian Landrace pigs

Abstract. Pedigree and field test data – collected between 1994–2005 – were analyzed in a group of 132,548 Hungarian Landrace pigs. The analysed traits were average daily gain (ADG) and lean meat percentage (LMP). In the present study inbreeding coefficients, pedigree completeness (complete generation equivalents) and inbreeding depression for ADG and LMP were estimated. Increasing the number of generations that were considered in the pedigree the estimated inbreeding coefficients did not change after the 5th generation, but pedigree completeness was continuously increased. The estimated inbreeding depression for ADG and LMP were different applying 40 different models but the magnitude of the differences was small. The model comparison showed that the models containing litter and year-month effects had the best fit (smallest mean squared error). Increasing the inbreeding coefficient by 10 % decreased ADG by 4.01 g and practically did not affect LMP (0.003 %). It can be concluded that the estimated inbreeding depression was small and substantial depression can not be expected in the near future. However, the low level of inbreeding of the studied population can partly be explained by the short pedigrees. This suggests that Hungarian pig breeders may often import breeding animals or carry out herd replacements rather than applying continuous within group selection.