Methionine and lysine are essential amino acids that are frequently limiting for milk protein synthesis and, consequently, milk production in dairy cows. Supplementation with these amino acids has been proposed as a strategy to improve N utilisation by increasing the efficiency of dietary protein use, thereby reducing N losses through urine and faeces while maintaining or enhancing milk yield and protein production. This approach may be particularly beneficial during critical physiological stages when nutrient demands are elevated, such as the transition period around calving and the mating period. When methionine and lysine supply is insufficient, other absorbed amino acids cannot be fully utilised for protein synthesis, resulting in increased amino acid catabolism and N excretion. Providing a more balanced amino acid profile may therefore allow cows to maintain production with lower dietary crude protein levels, improving N use efficiency and reducing environmental N losses. Furthermore, methionine and lysine have been associated with roles in immune function and antioxidant metabolism, which may support cow health during periods of increased metabolic stress, such as calving and early lactation. Therefore, the objective of this study is to investigate the effects of a balanced-on Amino Acids diet with KESSENT™ MF Arome and LysiGEM™ on animal performance, milk urea and inflammatory response in an Spring calving dairy herd.
