ARTICLE 58 FEED & ADDITIVE MAGAZINE September 2025 MODULATION OF IMMUNOMETABOLISM WITH METHIONINE While the transition period is one of the most challenging times in the life of dairy cattle, it has been well-documented that enhancing Met supply through RPM improves immunometabolism in transition cows via better liver function, greater GSH production, lower oxidative stress and inflammation, and improved immune function (Coleman et al., 2020). These improvements in immunometabolic markers have been associated with not only better dry matter intake (DMI) and performance, but also better health. Moreover, Met supplementation supports immunometabolism and sustains performance during heat stress through reductions in oxidative stress, as well as improved mTOR signaling in the mammary gland and liver. However, one question was whether Met supplementation could also improve the health and performance of dairy cows in response to a specific health disorder, such as mastitis, and if Met influences mTOR signaling of immune cells. BENEFITS OF METHIONINE DURING A SUBCLINICAL MASTITIS CHALLENGE Those questions were tackled by a recent publication utilizing a subclinical mastitis challenge (SMC; Paz et al., 2024). In that study, cows (145 ± 51 days in milk) fed Smartamine® M (SM) (0.09% dry matter; +13.4 g metabolizable Met; 2.53 Lys:Met) for 21 d prior to a subclinical mastitis challenge (SMC) with Streptococcus uberis demonstrated: • Improved milk production: Despite no difference in DMI, SM cows produced more milk fat, protein, and energy corrected milk (ECM) (Figure 2) during the first 72 h post-challenge vs. cows not fed supplemental Met (CON), highlighting the importance of Met for sustaining production during a period of stress. • Less inflammation and oxidative stress: Cows fed Met showed favorable changes in liver and plasma biomarkers (GSH and the genes that synthesize it, reactive oxygen species and inflammatory markers) during the SMC, indicating lower local and systemic oxidative stress and inflammation, likely supporting improved performance. • Greater mTOR signaling in immune cells: In Met-supplemented cows, phosphorylation of the mTOR pathway proteins AKT, S6RP, and 4EBP (key players regulating the initiation of protein synthesis) was increased in milk and blood immune cells. This indicates greater activation of protein synthesis (LaplanHours Relative to SMC Energy Corrected Milk Production During the First 72 h Post-challenge SM CON 30 28 26 24 22 20 18 16 14 Trt, P = 0.02 Time, P < 0.01 Trt x Time, P = 0.09 ECM (kg/milking) 0 12 24 36 48 60 72 Photo: Freepik Figure 2
RkJQdWJsaXNoZXIy MTUxNjkxNQ==