Niacin-lipid interactions in lactating dairy cows

Niacin-lipid interactions in lactating dairy cows were investigated. Treatments were: control, nicotinic acid (12 g/d), calcium salts of long chain fatty acids (3% diet dry matter), and calcium salts of fatty acids with nicotinic acid. Cows received treatment diets from week 2 to week 14 postpartum.Supplementation of nicotinic acid or calcium salts of fatty acids did not affect dry matter intake. Milk yield of Holstein cows fed calcium salts of fatty acids was increased, but milk protein content was reduced. Milk yield and milk protein content of Jersey cows were not affected by treatment. Milk fat content was not altered by calcium salts of fatty acids or nicotinic acid for either breed. Nicotinic acid supplementation increased protein content and yield from Holstein, but not Jersey cows. Increased solids-not-fat content in milk from Holstein cows supplemented with nicotinic acid was due to the increase in milk protein content.Amino acid uptake by the mammary gland was variable. Apparent total tract nutrient digestibilities were not affected by treatment, except for hemicellulose in Holstein cows which was enhanced by calcium salts of fatty acids. Blood plasma non-esterified fatty acid concentrations were increased and glucose concentrations were decreased when Holsteins were fed calcium salts of fatty acids. Body weight change was not affected by treatment. Blood plasma $\beta$-hydroxybutyrate concentrations were increased by feeding calcium salts of fatty acids and decreased by feeding nicotinic acid to Holstein cows.During weeks 15 and 16 postpartum, all cows were placed on the control treatment. Holstein cows formerly fed calcium salts of fatty acids maintained an elevated milk yield. Milk fat content was reduced for all cows, indicating that during the treatment period dietary fat was replacing adipose tissue as the source of milk lipid.There were no benefits of supplementing either calcium salts of fatty acids or nicotinic acid on reproductive performance. When cows were placed on the control treatment, energy balance was increased.Supplementation of either nicotinic acid (12 g/d) or nicotinamide (12 g/d) tended to reduce epinephrine stimulated lipolysis in dairy cows. Niacin supplementation increased the population of entodiniomorph protozoa in the rumen.U of I OnlyETDs are only available to UIUC Users without author permissio