INFLUENCE OF LIPID METABOLISM ON THE QUALITY OF CATTLE MILK

Abstract

The profitability of dairy farming in enterprises of the Sumy region is always an urgent issue, because not only the quantity of milk produced, but also its quality directly affects the profitability of farms. Enzymes in the animal's body play an important role in animal productivity and, accordingly, in the general metabolism of animals, so our task was to study the effect of changing the diet of cows (with the addition of rapeseed and soy) on the composition and quality of milk, including the profile of fatty acids in the milk of the Ukrainian black-and-white cattle breed. Milk contains milk balls with a diameter of up to 4-5 mm that are formed from milk fat, in particular fatty acids with a fairly dense membrane. And this is very important in terms of protection against damage to their membrane by enzymes, especially lipase. Otherwise, when damaged, milk fat is hydrolyzed with the release of a large amount of free fatty acids. And this, in turn, leads to lipolysis, which can be caused by a violation of lipid metabolism in dairy cows, destruction of milk fat by lipase by milk enzymes. In addition, lipolysis of milk fat can be a consequence of bacterial contamination of milk and the development of microorganisms. In addition, the increase in the volume of fatty acids can occur due to the obvious mechanical deformation of fat deposits during milking. Fatty acids for the synthesis of fat in milk can be of several types: 1) Long-chain fatty acids (more than 16 carbon atoms per molecule) – are produced from the absorption of fatty acids and dietary fats that enter the blood from the gastrointestinal tract, and non-esterified fatty acids (NFA) from the body's fat reserves. 2) Short-chain (containing up to 8 carbon atoms) fatty acids. 3) Medium-chain (from 10 to 14 carbon atoms) fatty acids – are formed in the mammary gland by "de novo" synthesis (that is, they are created "newly" in the mammary gland from smaller molecules). The increased ratio between the amount of saturated and unsaturated fatty acids in milk fat has a negative effect on its industrial value, since there is a positive relationship between the consumption of saturated fatty acids and various diseases and elevated cholesterol levels in humans. A high consumption of palmitic, myristic and lauric acids can be particularly dangerous due to their effect on high cholesterol and LDL concentrations in the blood, and conversely, the consumption of unsaturated fatty acids has the opposite positive effect. Body fat significantly affects the composition of fatty acids in animal milk. After all, the body of a cow synthesizes lactic fatty acids from various substances, a part of which enters the body with feed and is excreted together with milk. It is also affected by the breakdown products of the rumen of cows. Therefore, the composition of fatty acids depends entirely on the microflora of the rumen. The main source of fatty acids in milk can also be bacteria that die during digestion. Animals of the same condition were selected for the experimental group. The composition of milk fatty acids was determined. Animals fed canola seed compared to animals fed soybean seed showed a higher fat percentage of 4.1%, body condition score and milk urea nitrogen showed a significant difference between the two groups. The amount of a number of fatty acids in the animals fed the two different diets was different, and their amount varied significantly. Because canola seed contains more fat and protein than soybeans, it can compete as a substitute for soybeans in the diet of dairy cows. In addition, rapeseed with a nutritional effect on the composition of milk fatty acids can be used to improve the quality of milk.