Cow's milk is the main agricultural product and a valuable raw material for the production of dairy products. During the study the quality of milk, organoleptic, microbiological and chemical indicators are determined. The chemical composition of milk depends on many factors – the breed of cows, feeding, content, age, physiological condition of the animal, season of the year, etc. The chemical composition of raw milk is an important condition in deciding on its further processing for a certain type of dairy product. Modern national and international regulatory documents impose low requirements for the mass fraction of fat and protein in cow's milk – at least 2,8 %. Milk with a minimum content of fat and protein does not allow to obtain products with high yield. To plan the production of dairy products, it is necessary to take into account seasonal changes in the chemical composition. The Chuvash State Agricultural Academy has a small dairy farm. The academy has a training and research laboratory on the technology of milk and dairy products. In the conditions of this laboratory, milk of cows, not only of our academy, but also of personal subsidiary, farm and collective farms are examined. In this regard, it is relevant to conduct research to identify seasonal changes in chemical composition of milk. Our article presents the results of research work on determining the chemical composition of milk of cows in the dairy farm of educational scientific and practical center «Studenteskiy» of the Chuvash State Agricultural Academy in autumn. It was revealed that in September, October and November, the content of fat and protein in milk significantly increases.
Seasonal changes in the PM1 chemical composition north of Mexico City