Effect of rumen-protected methionine supplementation and its relationship with lipid metabolism in high-producing dairy cows with different dietary energy concentrations

A post-absorptive link between amino acid supplies and lipid metabolism has been suggested and evidenced. The objective of this trial was to determine the effect of methionine (MET) supplementation at 2 levels of dietary ME on the performance of mid-lactation dairy cows. A total of 112 multiparous Holstein cows (49.4 ± 5.3 kg/d of milk and 146.6 ± 68.2 DIM) from a commercial herd in Southern Brazil were blocked by lactation number, J. Dairy Sci. 103 (Suppl. 1) 299 milk yield, and DIM. Cows were divided into 4 isoprotein (16.6% CP) diets: control (CON; 1.62 NEL Mcal/kg DM); high energy (HE; CON +1.2% of DM of hydrogenated fat (Prius F 100 Nat Dry, Auster)); methionine (MET; CON + 24 g of Smartamine M, Adisseo SA); and HE+MET (HE + 24 g of Smartamine M). The total experimental period was 38 d, and the first 3 d were used as a covariate with all cows fed the CON diet. Total mixed ration was provided once a day, with or without the addition of HE treatment, while MET treatments were top-dressed twice a day. Milk yield data were recorded 3 times a day, while milk samples for composition were collected weekly, as well as in the last 9 consecutive milkings of the experimental period for composition, fatty acid profile, and gene expression. Data were analyzed using the MIXED procedure of SAS with repeated measures. The greater supply of MET showed the potential to alter lipid and protein metabolism, enhanced with an energy-dense diet (Table 1)