Young Scholar Presentation: Methionine Supply Enhances Performance, Alleviates Inflammation and Alters Utero-Placenta Nutrient Transport in Dairy Cows

Our research examined the effects of enhancing methionine supply on performance, immunometabolic responses, and utero-placental nutrient transport of dairy cows. Sixty multiparous Holstein cows were used in a block design and assigned to a control diet or the control plus rumen-protected methionine (RPM; Mepron, Evonik Nutrition & Care GmbH, Germany). Mepron was fed from −28 to 60 d relative to parturition at a rate of 0.09% and 0.10% of DM during the prepartum and postpartum period, respectively. That rate ensured that the ratio of Lys to Met in the MP was close to 2.8:1. Compared with control, during the fresh period (1-30 DIM) RPM increased DMI by 1.7 kg/d, milk yield by 4.1 kg/d, fat yield by 0.17 kg/d, and milk protein yield by 0.20 kg/d. During the high-producing period (31-60 DIM), cows fed RPM increased DMI by 1.45 kg/d, milk yield by 4.4 kg/d, fat yield by 0.19 kg/d, and milk protein yield by 0.17 kg/d, compared with control. RPM supplementation reduced plasma fatty acids in the fresh period and decreased γ-glutamyl transferase, cholesterol and paraoxonase indicating better liver function. Among the inflammation biomarkers measured, RPM led to greater albumin (negative acute-phase protein) and lower haptoglobin than control cows. Cows supplemented with RPM had greater plasma concentration of total, β-carotene, tocopherol, and reduced glutathione, whereas reactive oxygen metabolites were lower compared with control cows. Compared with control, RPM enhanced blood neutrophil phagocytosis and oxidative burst. Calves from RPM-supplemented cows had greater body weight at birth and upregulated MTOR protein expression in the placenta. Regarding placental nutrient transporters, RPM-fed cows had 5 upregulated neutral AA transporters (SLC3A2, SLC7A5, SLC38A1, SLC38A2, and SLC38A10). Among the facilitated glucose transporters, RPM upregulated the expression of SLC2A1, SLC2A3, and SLC2A4. In RPM-fed cows the long-chain fatty acid transporter SLC27A1 and the betaine transporter SLC6A12 were downregulated, while the multivitamin cotransporter SLC5A6 was upregulated. Overall, our results indicated that enhancing methionine supply to achieve a Lys:Met ratio of 2.8:1 during the periparturient period increased animal performance during early lactation, mitigated oxidative stress and inflammation, and enhanced liver and neutrophil function. Furthermore, utero-placental transport of essential and non-essential AA, glucose and vitamins during late-gestation also was enhanced. As such, difference in calf birth body weight was, at least in part, a result of upregulation of nutrient transporters some of which are controlled by mTOR signaling pathway.