INBREEDING AND INBREEDING DEPRESSION IN SLOVENIAN HOLSTEIN POPULATION

Analysis of inbreeding and inbreeding depression was done on the data of routine breeding value estimation for milk production data on Holstein population in Slovenia. A pedigree file of 106 433 animals born from 1952 to 2005 was investigated for the occurrence of inbreeding. The maximum inbreeding was 37.5. However average inbreeding coefficients of inbred cows (1.3 %) and of all cows with test day records (0.989 %) were low. Daily milk, protein, and fat yield of first five lactation for 86 122 cows were analyzed. Inbreeding was included in the animal model as a linear covariate. The regression coefficients of milk, fat, and protein yield, multiplied with 305 days present inbreeding depression of lactation yields, were -22.17 kg, -0.601 kg and 0.387 kg respectively, for 1 % of inbreeding.