[Analysis of the factors increasing bulls' breeding value]
1997
Zuka, L. (Latvian University of Agriculture, Jelgava (Latvia). Institute of Animal Science)
When evaluating bulls it is necessary to take into consideration factors which modify animal productivity. It can be done by preadjustments on factors or bringing factors into a linear mixed model. Based on the gathered data (1125 cows were analysed) systematic environmental factors influencing the record were defined. With the linear mixed model 53 bulls with several daughters' number were evaluated. One of the most important factors, which allows to increase evaluation precision, is balanced number of daughters for every bull in evaluation. After 100 days of first lactation of a bull's daughter, it is possible to determine his breeding value and plan the use of this bull in the future.
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