Genetic structure of the Rio Grande do Sul Landrace swine herd

Abstract

The breed structure of the pedigree swine Landrace in Rio Grande do Sul State, Brazil, was analysed by pedigree sampling methods. The number of herds changed from two in 1958 to 80 in 1977, with 23.275 registers for the twenty years. The herds registering swines in 1977 made it during 4.32 years and had 2.32 males and 7.80 females in the average. The group of imported animals plus eight herds contributed with 71.1 per cent of the genes. The imported boar PBB 2274 presented the largest direct relationship to the breed, with 12.5 per cent. The total inbreeding from 1958 to 1977 was 0.59 per cent, corresponding to an increasing of 0.06 per cent per generation. The average generation length was 24.5 months and the average replacement rates of boars from the same herd was 15.5 per cent in 1977. This was made by 21.2 per cent of the hers.