Effects of isoleucine, lysine, valine, and a group of non-essential amino acids on mammary amino acid metabolism in lactating dairy cows

“Effects of isoleucine, lysine, valine, and a group of non-essential amino acids on mammary amino acid metabolism in lactating dairy cows.” Unbalanced dietary AA can affect AA transport by mammary glands. In the current work, infusions of Ile and Lys did not self-stimulate transport regulation nor affect net uptakes of other AA. Infusions of Ala, Gln, and Gly (AQG) increased mammary Tyr clearance rates but did not affect net uptakes of any AA. Ile, Lys, and AQG infusions did not affect milk protein production, but Val infusions decreased DMI, milk protein production, and mammary net uptakes of Leu, Lys, Met, and Na+-dependent transported AA. Val infusions limited nutrient supplies to the mammary glands and appeared to downregulate mammary AA transport.