Milk Protein Level

one of the important qualitative indicators of the milk productivity of animals. It is expressed as either the percentage or weight content of protein in milk.

The average total protein content in the milk of different species of farm animals (in percent) is 3.3–3.4 for cattle, 4.0 for buffalo, 4.3 for zebu, 5.0 for yaks, 2.1 for mares, 2.2 for asses, 3.5 for camels, 6.0 for sheep, 4.0 for goats, and 7.2 for hogs. The protein content in milk also depends on the breed, lactation period, feeding and maintenance, health, and physiological condition of the animal, as well as other factors. For example, the protein content is 3.5 percent in the milk of Iaroslavl’ cows and 3.3 percent for Kholmorgory cows.

The protein level in the same breed changes: it reaches 14–22 percent in the colostrum; by the tenth day after calving it is at its average level for the breed; by the second or third month of lactation it is at its lowest level; and toward the end of lactation it again increases. During estrus or shedding and with emaciation the amount of protein in the milk decreases. An increased protein content in the feed is usually associated with an increase in protein in the milk, but it should be taken into account that it is physiologically dangerous and economically unprofitable to feed too many proteins. The age of animals and milking technique do not exert a significant influence on the milk protein level. Milk protein level is a hereditary quality; therefore, it is necessary to select this quality in animal breeding. An important criterion for evaluating sires is the milk protein level of their female offspring.