Genetic structure of the Brazil Hampshire swine herd

Abstract

The breed structure of the pedigree Hampshire in Brazil was analysed from records of the Brazilian Pig Book, and by the pedigree sampling method. The number of herds for the 1973 to 1980 period was 42, changing from eight in the first year to 17 in the last year. The total number of records was 3,548 for eight years. During the period, the average existence of the herds in the Pig Book was 3.10 years and the herd average sire was 1.5 boars and 6.5 sows. The most important herds, according to their genetic contribution for the breed were: the group of imported progenitors, plus the herds Seara, SC, Raquel, SC, Emboque, PR and Cruzeiro do Sul, PR. The imported boar PBB 1053 and the brazilian boar PBB 247 presented the largest direct relationship to the breed (10.2%), followed by the boars PBB 1557(9%) and PBB 1740 (8.6%).The sows with largest relationship were the imported PBB 1555 (6.7%) and the brazilian PBB 1369 (6.7%). The total Inbreeding up to 1980 was 3.13%, corresponding to an increasing of 0,81% per generation. The strains breed subdivision index was 0.33, meaning the inexistence of a natural strain formation, within the breed. The average generation length was 29,4 months and the average age of the males and females, when the progeny was born, corresponded to 27.6 e 31.2 months, respectively. The average replacement mate of boars from the own herd, considering all the farms, was 66.7%. The 33.33% of the farms were classified as Elite, the 22.22% as Multiplier and the 44.45% as mixed, from a total of nine farms in the sample.