Leukemia virus in cattle and its effect on milk quality

The purpose of research is to study the features of the veterinary and sanitary examination of milk in case of cattle infected with the leukemia virus. The study was conducted from November 2020 to November 2021. The object of research is three-year-old cattle. The material of the study is the data of examinations of the Department of Laboratory Diagnostic Activities of the city of Novorossiysk. 100 RID-negative and 24 RID-positive animals were selected, the data of which were provided by the Department of Laboratory and Diagnostic Activities of Novorossiysk. From 15 heads from the Anapa Region and the Crimean Region, 3 groups of animals were formed. The main norms of cows' milk in terms of indicators in accordance with regulatory documents were investigsated. Physical and chemical studies conducted in a veterinary laboratory showed that in RID-positive and hematologically infected cattle, compared with the control group, the percentage of fat increased by 0.10 %, and the percentage level of milk proteins decreased by 0.1 and 0.3 % respectively. The total lactic acidity according to Turner reduced the level by 0.6 °T when compared with the control. According to the results of microbiological analyzes, the samples showed significant changes in their composition. In the 1st and 2nd experimental groups of animals, in comparison with the control, the content of mammary epithelial cells, leukocytes and others increased by 1.5•105 and 2.1•105 in 1 cm3, while the total number of microorganisms in milk increased by 0.10•105 and 1.25•105 CFU/cm3, respectively. Consequently, in hematologically ill cows with leukemia, microbiological parameters were higher than in the product obtained from infected animals. According to the characteristics, the milk of RID-positive animals and healthy cows corresponds to the current GOST 31449-2013.