Influence of Some Genetic and Environmental Factors on the Reproductive Traits in Cows

摘要

The objective of the present investigation was to study the effect of some genetic and environmental factors on the reproductive traits in the Bulgarian Black and White breed. The animals from three farms in the North-East of Bulgaria were subject ofthe investigation. The data of the age of fist calving (AFC) of 2943 heifers and the duration of 6101 calving intervals were processed. The effect of the various sources of variance was detected on the basis of LS-analyses with the following factors: genealogical line(j=l ...5), season of calving (1=1...4), period (p=l... 6), farm (k=l ...3) and number of lactation (n=1...2). The mean estimation of the age of first calving is 858.88 days, and of the calving interval -419.69 days. The value of the reproductive traits is influenced by the lactation number, the farm and the period, while the genealogical line and the season of calving do not significantly influence it.