Chapters authored
Niacin, Metabolic Stress and Insulin Resistance in Dairy Cows
The periparturient period in cows is associated with metabolic stress and a state of negative energy balance, which are characterized by increased lipolysis, ketogenesis, hepatic steatosis, oxidative stress and insulin resistance. Such metabolic changes may exert adverse effects on the health and milk yield of lactating cows. The pharmacokinetics of niacin in ruminants is specific as rumen microorganisms facilitate both the synthesis of tryptophan and the degradation of niacin. Niacin administration to cows leads to an increase in the coenzyme activity, encompassing the activity of nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). These coenzymes are actively involved in the metabolism of lipids and carbohydrates, whereas NAD protects the organism from oxidative stress. In periparturient cows, the supplementation of niacin has been found to induce depressed lipolysis and a limited impact of nonesterified fatty acids on all metabolic processes. It also results in decreased lipid peroxidation regardless of the magnitude of lipolysis in the periparturient period. Furthermore, niacin reduces the concentration of ketone bodies, thus preventing the development of fatty lever disease and ketosis in cows. The anti-inflammatory effect of niacin is manifested in stimulating the secretion of adiponectin and inhibiting immune cells.
Part of the book: B Group Vitamins