Population structure and effect of inbreeding on milk yield of Saanen goats in Brazilian production systems

The aim of this study was to evaluate the history of a population of Saanen goats based on the population structure and the effect of inbreeding on accumulated 305-d milk yield (MY305) and lactation length (LL). Pedigree records of 7640 individuals born between 1997 and 2014 were analyzed and population parameters were estimated based on the probability of gene origin, effective population size (Ne), average inbreeding coefficient (F), flock classification according to origin and use of breeding animals, average relatedness coefficient (AR), pedigree completeness and number of generations using the ENDOG v4.8 program. A total of 79.57 %, 50.73 %, 29.10 % and 11.60 % of the examined individuals had pedigrees in the first, second, third and fourth ascendancy, respectively. The total number of founders and ancestors was 123 and 101, respectively, and 39 of the latter explained 50 % of the genetic variability in the population, which indicates a loss of original genes. The AR and F coefficients were 0.78 % and 1.48 %, respectively. There was no significant inbreeding effect on LL. The MY305 was significantly affected by inbreeding, with a reduction of 2.31 kg per 1% increase in the individual inbreeding coefficient. The LL and MY305 exhibited heritability of 0.03 and 0.18 respectively, with a genetic correlation of 0.97.