INFLUENCE OF THE CALVING SEASON ON THE MILK YIELD GIVEN BY A FRIESIAN POPULATION, IMPORTED FROM THE NETHERL

The individual milk production at cows is influenced by several factors, which taken by their nature, may be genetic factors and environmental factors. The calving season has an influence on the milk production per lactation, through ratio structure and nutrition level and by climatic factors, as well. In this study the research was focused on the influence of the specified factor on the milk production in Frisian cows from Netherlands exploited in the eastern parts of Romania. The ascendance of cows was valuable, including mothers who had an average production of 7,923.4 kg milk, 4.23% fat and 287.97 kilograms pure fat. Paternal grandmother have achieved more superior yields then maternal mothers with average values of 8960.29 kg milk, 4.37% fat and 371.25 kilograms pure fat. The best milk production from the descendants was registered during winter season, 7,798.51 ± 204.07 kg of milk per total lactation and 7,379.31 ± 132.79 Kg of milk per normal lactation, the differences between seasons being statistically significantp> 0.05