Synteza białka w gruczole mlekowym krów mlecznych - modele, uwarunkowania i najnowsze poglądy

This paper compares several models of protein synthesis in the mammary gland of cows developed by using various statistical models. According to these models, it is possible to predict an increase in the amount of proteins in milk as a result of the addition of proteins or amino acids (AA) to dairy cows’ diet. It is difficult to increase the amount of proteins in milk via nutritional manipulation. In the case of dairy cows, the extra-ruminal addition of AA increases their intake, but an increase in the amount of proteins in milk is not always achieved, since the AA dose often does not include limiting essential amino acids (EAA). An additional factor that complicates protein transformations is AA metabolism in the small intestine and liver, which to a large degree influences the amount and profile of AA transferred to the mammary gland. The utilization rate of AA in the mammary gland depends on their concentration in arterial blood, the rate of blood flow through the udder, the transport process through cellular membranes and the level of amino acid metabolism in the gland. All these processes may be described mathematically by Michaelis-Menten kinetic equations. Nevertheless, the ideal model of protein synthesis in the mammary gland is yet to be developed. Also the role of the most important amino acids for that synthesis is not fully known. Among non-essential amino acids (NEAA), considerable importance is attributed to glutamine and asparagine.