Enhancing methionine supply alleviates inflammation and oxidative stress and improves liver function during the peripartum period in dairy cows

Abstract

During the transition period, which comprises three weeks prepartum until 3 weeks postpartum, dairy cows experience a state of systemic inflammation and oxidative stress. Because the energy consumed by the cow is not enough to meet the energy required for milk production, adipose tissue is mobilized and provides a source of energy for tissues like the liver. However, excessive release of fatty acids from adipose tissues impairs liver function. Furthermore, high plasma concentrations of fatty acids (NEFA) contribute to oxidative stress and uncontrolled inflammatory responses often leading to health problems. Besides being an important building block for milk protein synthesis, methionine is a precursor for synthesis of VLDL, antioxidants and other methyl‐group requiring compounds. Thus, we hypothesized that increasing the intestinal supply of methionine could help alleviate inflammation and oxidative stress, and improves liver function during the peripartum period in dairy cows. Sixty‐one multiparous Holstein cows were used in a randomized complete block design and were fed the experimental treatments consisting of a basal control (CON; n=31) diet with no methionine supplementation or the basal diet plus rumen‐protected methionine (MET; Mepron®, Evonik Nutrition & Care GmbH, Germany; n=30). Methionine was supplied from ‐28 days to 60 days relative to parturition at a rate of 0.09% and 0.10% of dry matter (DM) during the prepartum and postpartum period, respectively. From −45 to −29 days before expected parturition, all cows received the same diet [1.33 Mcal/kg DM and 13.9% crude protein (CP)] with no MET. The basal “close‐up” (from −28 days to parturition), early lactation (from 1 to 30 days) and high‐production (from 31 to 60 d) diets contained 1.47 Mcal/kg DM and 15.3% CP, 1.67 Mcal/kg DM and 17.7% CP, and 1.61 Mcal/kg DM and 17.4% CP, respectively. Blood samples from 15 cows/group without clinical diseases after calving were collected at −30, −14, 1, 7, 21, 30 and 60 days relative to parturition and analyzed for biomarkers of energy balance, liver function, inflammation and oxidative stress. The indicators of energy balance β‐hydroxybutyrate, glucose and NEFA were not affected by supply of methionine. Among the five biomarkers of liver function analyzed, MET led to overall greater (P = 0.01; 94.8 vs 84.0 U/mL) paraoxonase (negative acute‐phase protein) and lower (P = 0.01; 15.1 vs 22.9 U/L) γ‐glutamyl transferase compared with CON. For cholesterol, a treatment × time (P = 0.07; 4.0 vs 3.5 mmol/L) was observed due to a greater increase over time in MET than CON cows. Aspartate aminotransferase and bilirubin were not affected by supply of methionine. Among inflammation biomarkers measured, MET led to greater (P = 0.01; 38.1 vs 37.1 g/L) albumin (negative acute‐phase protein) while alkaline phosphatase, ceruloplasmin (positive acute phase protein), and myeloperoxidase were not affected by methionine supply. The lower concentrations of reactive oxygen metabolites (P = 0.07; 15.2 vs 16.8 mg of H2O/100 mL) in MET compared with CON cows indicated a state of reduced oxidative stress. Overall, the results indicate that increasing methionine supply by feeding rumen‐protected methionine is an effective approach to help mitigate inflammation and oxidative stress as well as to enhance liver function during the peripartum period in dairy cows.