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The paper substantiates the need to improve the energy and protein nutrition of heifers in order to increase the efficiency of their cultivation taking into account climate changes. In scientific and economic experiments on heifers, the energy-protein feed additive TEP-mix was used, with a high degree of protection against the breakdown of protein (65.25 %) and starch in the rumen.

The main results of the conducted research indicate that improving the energy and protein balance in the body of heifers due to the use of TEP-mix supplements in their diets is a physiologically justified and cost-effective element of feeding technology. The use of diets with the inclusion of TEP-mix additives in their composition provides an increase in the amount of protected protein and starch in the general diet, which has a positive effect on increasing live weight gain and improving the economic efficiency of cultivation.

The results prove that even in conditions of reduced feed intake due to increased outdoor temperature, providing heifers with protein and energy is a reliable way to control their productivity during critical temperature conditions for raising animals.

The developed diets for feeding heifers with the inclusion of high-protein energy feed additive TEP-mix with an energy-protein ratio of 8.1:1 provided an increase in the level of non-split in the rumen, contributed to the stabilization of metabolic processes in the animal body and allowed to increase the average daily growth of heifers in the cold season by 7.7 % , and in the summer by 20.8 %. Changes in the protein diet of heifers in the direction of saturation of the diet with protein, which is digested according to the intestinal type from 28.05% to 34.83% provided better tolerance to heat stress. Moreover, with an increase in temperature to the maximum, the degree of counteraction to heat stress becomes the greatest.

With a 10% increase in the normal protein level in the second group, the energy-protein ratio increased to 9.7:1, and the level of protein that is not broken down in the rumen decreased to 26.59 %. Under these conditions, the average daily weight gain of heifers in winter decreased by 3.0%, in summer – by 6.2 %.

 

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