Genetic structure of the Santa Catarina landrace swine herd

Abstract

The breed structure and genetic history of the pedigree swine Landrace in Santa Catarina State, Brazil, were analysed by pedigree sampling methods. (I) The development of the breed started in 1958 and was originated from imported animals, coming from European countries and Canada. The number of herds changed from four in 1958 to 126 in 1977, while the yearly number of registers increased from 40 to 15,677. Only one herd (0.34%) remained 20 years in activity and 262 (51.02%) were active up to two years. (II) The most important herds according to their genetic contribution to the breed were the group of IMPORTED animals plus SADIA, PAP-CNPSA and BAGDÁ farms. Due to their progressive contribution to the more recent generations, the herds IDEAL and VIVAN were also considered important. All together, those six herds contributed with 84,5% of the genes to the Santa Catarina Landrace population of 1977. (III) The animal with the largest direct relationship to the breed was the imported boar number PBB 4523, which was born in 1966 and presented a relationship of 8.50 and 2.91%, for the 1968 and 1977 samples respectively. (IV) The degree of inbreeding was calculated based on 1958. The total inbreeding in 1977 was 1.09%, comprising 0.48% to current inbreeding and 0.61% to non-current inbreeding. (V) The effective generation length was 25.2 months. In the 1977 sample, 65% of the animals descended from more than two-year old boars, and 59% from dams with an age not superior than two years. (VI) The average replacement rate of boars from the same herd was 20.4% verying from 24.4% to 31.6% is the Elite farms tier. The multiplier tier reached a replacement rate of 12.6% of boars from the same herd.