Inbreeding effect on reproductive traits in a herd of Mangalarga Marchador Brazilian horses

Abstract

This work aimed to evaluate the effect of inbreeding on the reproductive characteristics such as age at first foaling, gestation length, foaling interval in a “Mangalarga Marchador” herd in the North of Minas Gerais State, Brazil. The relationship matrix involved 2186 animals from the general register of the Catuni Farm. The inbreeding coefficient (F) was calculated using the subroutine MTDFNRM present in the MTDFREML program and its effect on the reproductive indexes was evaluated through simple linear regression. Average F of the population was of 1.45% and, of the total, 27.59% of the animals were inbred. Among the inbred animals, average F reached 5.28% (minimum of 0.1 and maximum of 28.13%). The average age of the stallions, when their foals were born, was 9.06 years while for mares it was of 8.90 years giving a medium interval of 8.98 years. The age at first foaling, gestation length and foaling interval were on average 4.71 ± 1.832 years, 327.94 ± 15.58 days and 547.78 ± 316.62 days, respectively while the herd effective size was of 185.25 animals. Effect of inbreeding on the reproductive characteristics was not significant. The inbred matings did not affect the reproductive characteristics of the Mangalarga Marchador herd. Controlled mating keep inbreeding at low values, what avoids inbreeding depression.