Inbreeding depression on dairy cattle for reproduction traits and milk production

Abstract

The aim was to evaluate the levels of inbreeding in dairy cows in a closed herd, and intensive system on Lima dairy region, and the endogamic depression on the reproductive traits of the number of services to pregnancy, number of calving per cow, length gestation, age at calving (first and two or more calving), calving intervals, open days and on milk production (305 days, 3 milking). 38 666 pedigree records were evaluated to determine the inbreeding coefficients of the cows and 5 356 production records to evaluate inbreeding depression. Linear models were used considering age as a covariate, as well as regression models to assess inbreeding depression. The average inbreeding coefficient increased per year of birth was +0.13%, the highest value of inbreeding was observed in animals born in 2021 (9.39%). Six groups were formed: non-consanguineous and consanguineous cows with an interval of 3.125% inbreeding. No inbreeding depression was observed on the reproductive characters of number of services per pregnancy, age at first calving and successive calving’s, open days and for milk production, while for the number of calving’s per cow it was determined that there is a reduction of 0.04 fewer calving per cow, gestation length affected by -0.16 days, calving interval an increase of 0.028 days for each 1% increase of inbreeding. Monitoring of inbreeding is necessary to avoid an increase of inbreeding, implement a system mating of minimum inbreeding.