Effects of biotin and nicotinamide supplementation on glucose and lipid metabolism and milk production of transition dairy cows

This study aimed to evaluate the effect of supplementing biotin (BIO), nicotinamide (NAM) and their interaction on feed intake, milk production, and energy metabolism of transition dairy cows. Forty multiparous Holsteins were assigned randomly within block to 1 of the following 4 treatments: control (no supplementation), 30 mg/d BIO, 45 g/d NAM (ruminally unprotected), and 30 mg/d BIO + 45 g/d NAM. Cows were fed the same basal diet and received the supplements in drenches daily from about d −14 to 35 relative to parturition. Feed intake, energy balance and calf birth weight were not affected by BIO supplementation whereas NAM supplementation tended to increase prepartum dry matter intake and decrease body weight loss. Tendencies of BIO × NAM × week interaction were observed on energy balance during prepartum and entire period. The interaction of BIO × NAM was found on milk lactose percentage and fat yield. Supplementation of BIO resulted in increased concentration of BIO in plasma and decreased triglyceride concentration. The BIO × week interaction effects were detected for triglyceride, very-low-density lipoprotein cholesterol and low-density lipoprotein cholesterol concentrations. Supplementation of NAM increased plasma NAM and glucose while decreased nonesterified fatty acid, β-hydroxybutyric acid, triglyceride, high-density lipoprotein cholesterol and low-density lipoprotein concentrations. The BIO × NAM × week interaction effect was observed on nonesterified fatty acid concentration during entire period. Blood insulin and total cholesterol concentrations were not affected. Supplementing BIO and NAM in a combination did not show additional benefits above those observed for BIO or NAM supplementation alone for most of the variables. In conclusion, drenching ruminally unprotected NAM at a high dose (45 g/d) is effective to provide utilizable NAM and elicit beneficial effects on the energy metabolism of transition dairy cows.