Diagnosis of the nutritional value of colostrum in cows of different milk yield
When forming in an organism of a newborn calf of tentative immunity, the main source of immunoglobulins, a lysozyme, the functionally active leukocytes and lymphocytes, a colostrum is. The quality of a colostrum is a very important condition for formation of full-fledged immunity. A number of scientists claim that cows of different lactic breeds considerably differ on the level of lactic efficiency, at the same time the mass fraction of immunoglobulins negatively correlates with amount of colostrum at the first milking. Studying of dynamics of quality of a colostrum depending on the size of a milk yielding of cows for a lactation was a primal problem of researches. As an object of researches served the cows of four breeds divorced in the Samara region: Black Pied breeds, Bestuzhev, Holstein and Ayrshire. It is established that the content of immunoglobulins in a colostrum of the first yield of milk at cows of different breeds changes under the influence of the level of lactic efficiency and also with the animals' age. The highest content of immunoglobulins was in a colostrum of Bestuzhev breed – 103.35-81.38 g/l, and the lowest at Holstein breed – 74.52-42.29 g/l. Immunoglobulins of a colostrum are divided into three classes – IgG, IgA, IGM. In a colostrum of the first milk yielding of cows of Black Pied breed the share of IgG makes 84.1-85.5%, Bestuzhev breed – 85.7-86.3%, Holstein – 83.9-84.4%, Ayrshire – 85.7-86.6%. The tendency of increase in a share of IgG, in process of increase in milk yields of cows for a lactation is noted. It is established that at increase in level of lactic efficiency of cows, the quality of a colostrum decreases and the number of incidence of calves increases. As a result, the size of average daily gain of young growth live weight proportionally decreases. On the basis of the received results we recommend to estimate quality of a colostrum of the first milk yield by means of an optical or digital refractometer. Carry out the targeted selection work with breeds in the direction of colostrum upgrading.