Genetic structure of the Brazil Duroc swine herd

Abstract

The breed structure on the pedigree Duroc in Brazil was analyzed from records of the Brazilian Pig Book and by the pedigree sampling method. I. The number of herds for 1958 was 19, and 180 for 1980. The total number of records was 209.164 for the 23 years. During the period, the average existence of the herds in the Pig Book was 6.3 years and the herd average size was 2.6 boars and 14.5 sows. II. The most important herds, according to their genetic contribution for the breed were: the group of imported progenitors, plus the herds Ideal (RS), Jaqueline (SC), Raquel (SC), Itaberaba (SC), D. Rita (RS), Irene (SC), Perdigão (SC) and Ingá (SP). III. No one progenitor (male or female) presented a breed relationship superior to 3%. IV, The total inbreeding up to 1980 was 1.06%, corresponding to an increasing of 0.11% per generation. The strains breed subdivision index was 3.25, meaning the starting of a national strain formation. V. The average generation length was 27 months and the average age of the males and females, when the progeny born, corresponded to 28.3 and 25.5 months, respectively, VI. The average replacement rate of boars from the own herd, considering all the farms, was 13.6%. The 57.1% of the farms were classified as Elite, the 30.6% as Mixed and the 12.3% as Multiplier, from a total of 153 farms in the sample.