RELATIONSHIP BETWEEN INBREEDING AND DAILY MILK PRODUCTION IN HOLSTEIN COWS

The aim of this study was to evaluate the effect of inbreeding on milk production in Holstein cows (milk in kg; fat and protein content in %) during the first five daily milk controls (first lactation). This period is very important because is associated with a large increase in milk production and with total milk production at lactation. Daily production of inbred cows (Fx = 3.125 − 25 %) and their non-inbred half-sisters (Fx = 0) was compared. The non-inbred half-sisters had the same sire, the calving was carried out on the same farm, in the same year (± 2 months) and the dam reached a similar breeding value for kg of milk (± 5 %). The degree of inbreeding was evaluated to the fifth generation. Statistical evaluation was carried out using paired tests and ANOVA (GLM) − in a program Statistica®. The following fixed effects were included in the calculation: degree of inbreeding, somatic cell count, relative breeding value of sire and dam. The results showed a trend to the negative impact of inbreeding on daily milk production at the first and second controls. There is also an obvious tendency to lower milk production in the case of a higher somatic cell count.