Antioxidant activity of cow's milk depending on a single milk yield
Authors:   Federal Research Center for Animal Husbandry named after Academy Member L. K. Ernst, Dubrovitsy, city of Podolsk, Russia, Voronina Oksana A. , Savina Anastasia A. ,   Federal Research Center for Animal Husbandry named after Academy Member L. K. Ernst, Dubrovitsy, city of Podolsk, Russia, Zaitsev Sergei Y. ,   Federal Research Center for Animal Husbandry named after Academy Member L. K. Ernst, Dubrovitsy, city of Podolsk, Russia
Published: October 2022

Milk is an important object of research because it contains a large number of biologically active compounds (BAS) necessary for human and animal nutrition. Many of the BAS in milk have important antioxidant properties that require more detailed study. The aim of the work was to determine the relationship between the total amount of water-soluble antioxidants (TAWSA) and other biochemical parameters of the milk of Black-and-White cows depending on a single milk yield. Milk samples of Black-and-White cows were obtained in the amount of 194 units from the breeding farm «Ladoga» and studied in the laboratories of the Federal State Budgetary Scientific Institution FITs VIZh named after. OK. Ernst. From these cows, two conditional groups were formed depending on the time of a single milking: 1) morning (103 samples) or 2) evening (91 samples), respectively. The analysis of the main parameters of cows' milk was carried out by modern biochemical methods, and the amperometric method was used for TAWSA analysis. From the obtained new results, it seems possible to single out not only the contribution of each indicator in the initial milk raw materials, but also the correlations (obtained for the first time) between the TAWSA of cows' milk and one-time milk yields. As follows from the comparison of the data of groups 1 and 2, the main changes are associated with a significant decrease (almost 2 times) in the single milk yield in the evening compared to the morning. At the same time, the mass fraction of fat increases significantly (by 18%), while the mass fraction of ist. and total protein increase slightly (by 1,6–1,2 %, respectively). These data are consistent with the general trends of an increase in BAS in milk with a decrease in the total volume of its secretion by the mammary gland. The correlations we obtained between the values of morning or evening milk yield and mass fractions of fat, true and total protein are moderate and negative in the range from (–0,32 or –0,06) to (–0,26 or –0,32). Similar relationships were obtained between the value of the total (daily) milk yield and the mass fractions of fat, true and total protein are moderate and negative (–0,44; –0,24 and –0,25, respectively). These data are in line with reasonable trends, showing that an increase in single milk yields leads to a decrease in fat and protein in milk. In addition, the correlation between the values of TAWSA between each other during morning and evening milking is quite strong and positive (0,72). Since the level of antioxidants significantly affects the shelf life, nutritional value, and many other parameters of milk, the authors suggest using the TAWSA level as an additional parameter in the overall assessment of milk quality.