Effects of rumen-protected gamma-aminobutyric acid on feed intake, performance and antioxidative status in transition cows.

摘要

The objective of this study was to investigate the effects of non-protected and rumen-protected gamma-aminobutyric acid (GABA) supplementation on dry matter intake (DMI), energy balance, milk performance, and serum metabolites in transition cows. Forty cows were blocked based on previous milk production, parity, estimated calving date and body weight and were randomly assigned to one of four treatments and received either no GABA (control) or were supplemented with non-protected GABA (0.6 g/day) or rumen-protected GABA (0.6 and 1.2 g/day), respectively. The experiment lasted from week 2 before calving to week 4 after calving. Milk yield and milk composition were recorded weekly. Serum concentrations of GABA, neuropeptide Y, cholecystokinin, leptin and biochemical and antioxidative metabolites were analyzed weekly. In week 3 and 4 after calving, DMI was higher (P<0.05) in the cows fed 1.2 g/day rumen-protected GABA, compared with that of the control. In week 4 after calving, milk protein yield was higher in the cows fed 1.2 g/day rumen-protected GABA than that of the control cows. No differences were observed in the serum concentrations of GABA, neuropeptide Y and leptin among all the treatments, while non-esterified fatty acids and cholecystokinin concentrations decreased (P<0.01) in cows fed rumen-protected GABA on day 15 and 22 after calving, respectively. Serum total antioxidative capacity and concentrations of glutathione peroxidase and superoxide dismutase were higher (P<0.05) at several sampling points in cows fed rumen-protected GABA. In conclusion, supplementation of rumen-protected GABA at 1.2 g/day increased feed intake, improved milk protein yield, and decreased non-esterified fatty acids suggesting supplementation may be beneficial to postpartum dairy cows.