Overview of Encapsulated Lysine and Methionine and Their Impacts on Transition Cow Performance and Health

Dairy cattle's lactation efficiency has increased over the last decades, which is mainly attributed to high milk production and elevated nutrient requirements, especially protein and amino acids (AA) requirements. The transition period is considered one of the most crucial periods of a dairy cow's life, with the largest number of health disorders happening within the first 14 days in milk. Changes in dairy cow metabolic conditions might have had a severe impact on dairy cow health, fertility, and production, particularly milk and milk component yields. One of the applied strategies to prevent these negative impacts is balancing amino acids profile in dairy cattle feeds, primarily, rumen bypass methionine and lysine (RPM and RPL) to meet the requirements through increasing the metabolizable amino acid (AA) for intestinal absorption. NASEM (2021) presented a novel concept based on considering 5 indispensable amino acid (IAA) rather than the more aggregated metabolizable protein (MP) and the Lys–Met ratio. Continued attempts to improve the understanding of AA pathways make the possibility of new strategies to minimize the negative impacts on dairy cow metabolic status changes. Previous research observed beneficial impacts of supplementing RPM and RPL in transition dairy cow diets either/both (pre‐and postpartum periods) on dry matter intake, milk performance, plasma AA concentration, the occurrence rate of metabolic disorders, and immune response; however, the findings were inconsistent. Therefore, this review focused on the inconsistencies in the data and sought research gaps in this area.