К. Н. Нарожных Biochemical processes occurring in of cattle related to their elemental status. Therefore, the search for models of in vivo assessment of the level of zinc in the muscle tissue of animals is relevant. The level of zinc in muscle tissue influences the quality indicators of beef. The samples of the diaphragmatic muscle weighing 100 g were taken from Hereford cattle bred under typical conditions of an agribusiness sector in the south of Western Siberia (Russia). Elemental analysis was carried out by the atomic absorption method with electrothermal atomization on a spectrometer MGA-1000. Measuring of hematological parameters – erythrocyte, leucocyte and haemoglobin levels – was carried out on an automatic hematological analyzer PCE-90VET. Biochemical parameters were determined using photometric methods on a Photometer-5010 biochemical analyzer. The coefficients of regression models were calculated using the least squares method. The choice of the most accurate and effective model was made on the basis of a comprehensive assessment of indicators of internal and external quality criteria. The values of the dependent variable correspond to the Gaussian one. A high correlation between independent variables was revealed. The selection based on internal and external quality criteria revealed an optimal model for predicting the level of zinc in muscle tissue of Hereford cattle, containing three predictors: erythrocyte sedimentation rate (mm/h), color index and total cholesterol (mmol/l). The model meets the necessary assumptions: the residuals are normally distributed, there are no autocorrelations, and the observations are influential. There is no evidence of multicolleniality between the main effects of the main model (VIF = 1.0–1.1). The resulting model can be used for in vivo assessment of the level of zinc in the muscle tissue of cattle.
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