The Effect of Soy Flour on the Chemical Composition of Milk and Milk Producing Ability in the Diets of Cows During Their Lactation

Abstract

This article deals with the study of the effect of heat-treated soy bean flour included in the diet of lactating cows on amino acids, mineral composition of milk; the content of dairy protein, its fat, as well as on the milk producing ability of animals. As a result of the conducted research, it was revealed that the content of free amino acids, both interchangeable and irreplaceable in the milk of animals of the experimental group who received soy flour, was higher than in the control group during the lactation. With the course of lactation, qualitative and quantitative changes are noted in the amino acid composition of milk in animals of both groups. The content of minerals such as calcium, phosphorus, magnesium, sodium, potassium in milk was slightly higher during all periods of milk productivity in the experimental group of animals than in the control group. During the whole lactation period, the studied macronutrients were subjected to quantitative changes. It was revealed that the introduction of soy flour into the diet leads to a significant increase of fat in the milk of experimental cows compared with control animals. Moreover, the difference in fat content in favor of animals receiving soy flour is insignificant during the first four months of lactation, after which this indicator increases sharply in the seventh month, and then gradually decreases by the tenth month. There is a definite tendency in the milk protein content to decrease in the second month of lactation and then to a gradual increase by the end of it. It should be noted that the amount of protein, unlike fat, increases evenly during lactation - for each month by an average of 0.05%, reaching the maximum value by the 10th month. From the analysis of the dynamics of average daily milk yields in experimental cows by months of lactation, it follows that in the first four months soy flour stimulates milk formation, and the average daily milk yield in animals of the experimental group during this period is significantly higher than the milk yield in the control group, respectively, by months of lactation by 10,35%; 13,26%; 12,22%; 14,57% with a significant difference. In the subsequent fifth, sixth and seventh months, the milk productivity of the experimental animals is also higher than in the control group, but this difference is less pronounced. Starting from the eighth month, the animals of the experimental group are inferior in terms of the average daily milk yield to the animals of the control group. The introduction of soy flour into the diet for the first 120 days of lactation has a stimulating effect on the formation of milk, and in the last 80 days - an inhibitory effect on this process.