Keywords: regression model, Ukrainian black-and-white and red-and-white dairy breed, paratypic factor, milk yield, somatic cell count
The results of the regression analysis of the influence of phenotypic factors on the milk productivity of cows and milk quality are presented. Reliable values of the regression coefficients of the second degree for the lactation month and lactation number indicate a non-linear relationship between these model indicators and milk yield. The value of the regression coefficient for day length indicates a positive effect of this indicator on daily hopes. The high daily air temperature had a negative impact on the milk production of cows. The negative value of the regression coefficient for the length of daylight hours is associated with a negative relationship between fat content and daily milk yield (0.225). This is also the reason for the opposite direction of the regression relationship between the fat content and the lactation month. A negative coefficient for the “daytime temperature” factor indicates that high critical air temperatures have a negative impact on both daily expectations and the fat content in milk. The negative value of the regression coefficient for the length of daylight hours is associated with a negative relationship between protein content and milk yield (0.305). This is also the reason for the opposite direction of the regression relationship of the protein content with the lactation month. A negative coefficient for daily air temperature indicates that high critical air temperatures negatively affect both daily milk yield and protein content in milk. The absence of a regression relationship between the age of the cow and the protein content in milk indicates a greater genetic dependence of this phenotypic indicator. The obtained regression coefficients indicate an increase in the somatic cells count in the milk of cows with age and month of lactation. Daylight hours and night air temperature have a negative relationship with the somatic cells count in the daily milk yield of cows. High daytime air temperature increases the somatic cells count in milk.
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