Non-genetic factors affecting milk yield and composition of Holstein-Friesian cows nested within natural ecological regions of Zimbabwe

Milk production is affected by genetic and non-genetic factors. Knowledge of these factors is essential for efficient management and accurate estimation of breeding values. The objective of this study was to establish and analyze non-genetic factors which affect milk production and composition in Holstein-Friesian cows. A total of 4 500 milk records from the Zimbabwe Dairy Services Agency (ZDSA) from 1999 to 2004, were used. Natural ecological region, month of calving and year of calving had significant (P<0.05) effect on milk yield, protein and fat composition. Therefore, correction for environmental effects is necessary to increase accuracy of direct selection for milk yield and composition.

کلیدواژه ها:

Natural ecological region ، Year of calving ، Milk yield ، Milk composition