Amino acid composition of milk of black-and-white cows in the winter-spring period of the year (message 1)

Abstract

Determination of the amino acid (AA) composition of cow milk, especially in terms of essential amino acids, is important and relevant. Recently, there has been an increase in publications on the improvement of methods for analyzing the AA composition of animal milk, primarily cows. The purpose of our research is to study the features of the amino acid composition of the milk of Black-and-White cows in the winter-spring period. The studies were carried out with samples of the “Ladozhskoye” breeding farm (Krasnodar Territory, Ust-Labinsky District). Group 1 (January) included 12 animals, groups 2 and 3 (March and April) included 22 animals each, i.e. a total of 56 animals. The cows were fed according to generally accepted norms. The determination of AA was carried out by ion-exchange chromatography with post-column derivatization of samples with ninhydrin on an LC-20 Prominence system (Shimadzu, Japan) and a column with an ion-exchange resin 4.6x150 mm (Sevko, Russia). New data on the AA composition of the milk of Black-and-White cows have been obtained. To author’s opinion, not only the absolute values of AA in milk are important, but also their ratios. For the first time, particular “rows” on the AA content in cow milk samples were obtained: Glu >> Leu > Lys = Pro > Asp > Val > Phe ≥ Ile ≥ Tyr > Arg = Ser > Ala = Thr ≥ His > Met > Gly > Cys (January) ; Glu >> Leu > Pro > Lys > Asp > Val > Phe > Arg ≥ Ile = Tyr ≥ Ser > Ala = Thr > His ≥ Met > Gly > Cys (March); Glu >> Leu > Pro > Lys = Arg > Asp > Val > Phe ≥ Ile ≥ Tyr > Ser > Ala ≥ Thr ≥ His ≥ Met > Gly > Cys (April). Our studies have shown a decrease in the AA amount of in cow's milk by spring (in March and, especially, in April), which can be explained by the adaptation of physiological and biochemical processes in the animal body during this period.