Influence of niacin and whole cottonseed on intake, milk yield and composition, and systemic responses of dairy cows.
Twenty-four Holstein cows (early postpartum) were used in a randomized complete block design with a 2 X 2 factorial arrangement of treatments to compare effects of nicotinic acid (niacin) and whole cottonseed. Cows were fed individually isonitrogenous complete mixed rations ad libitum, containing corn-soy concentrate, corn silage, chopped coastal bermudagrass hay, and either 1) 0% niacin and 0% whole cottonseed, 2) 0% niacin and 15% whole cottonseed, 3) .03% niacin and 0% whole cottonseed, or 4) .03% niacin and 15% whole cottonseed. Dry matter and energy consumption, actual milk yield, total milk solids, and milk fat yield were not affected by treatment. Either niacin or whole cottonseed increased milk fat percentage and 4% fat-corrected milk. Milk protein percentage and yield were higher with niacin supplementation but tended to be lower with cottonseed feeding. The milk protein depression with whole cottonseed was alleviated by niacin due to stimulation of mammary casein synthesis. Supplemental niacin tended to elevate glucose and insulin in blood plasma, but whole cottonseed tended to reduce these plasma components. Plasma urea nitrogen was higher in cows fed whole cottonseed. Plasma-free tryptophan tended to be slightly higher in cows receiving supplemental niacin.
D000818:Animals; D002417:Cattle / Q000378:metabolism*; D003369:Cottonseed Oil / Q000494:pharmacology*; D004041:Dietary Fats / Q000494:pharmacology*; D005260:Female; D007774:Lactation / Q000187:drug effects*; D008892:Milk / Q000032:analysis*; D009525:Niacin / Q000494:pharmacology*; D011247:Pregnancy; D014364:Tryptophan / Q000097:blood
D003369:Cottonseed Oil; D004041:Dietary Fats; D009525:Niacin; D014364:Tryptophan