Impacto da endogamia e de fatores ambientais sobre características leiteiras em cabras da raça murciano-granadina na Espanha

Abstract

This study aimed to evaluate the effect of inbreeding, as well as environmental factors such order of parity, age of goat at calving and contemporary group (herd-year-season), on the total production of milk, fat, protein and dry extract of Murciano-Granadina goats in Spain. Genealogical trees of 11,926 females were traced to calculate the inbreeding coefficient for each animal. Then 22,832 lactations of these females were analyzed, standardized to 210 days of lactation, containing information of the total milk, fat, protein and dry extract production. It was used the least squares method, including the fixed effects of order of parity, age of goat at calving and contemporary group, and the rate of inbreeding as a continuous variable, considering linear and quadratic effects. Only 1.18% of the animals presented inbreeding, and the average population was of low magnitude (0.24%). However, among inbred animals, the average was considered high (20.31%). The total average of milk, fat, protein and dry extract production are within the range considered normal for the breed. The variables order of parity, age of goat at calving and contemporary group exerted great influence on the milk production and composition. Inbreeding had quadratic effect on total milk production with minimum point at 10.59% of inbreeding. For total production of fat and dry extract the influence was positive linear. There was no effect of inbreeding on total protein production. In general, the inbreeding does not present a problem over the milk traits in the evaluated period.