In Experiment 1, effects of whole cottonseed (0, 5, 15, or 30% of the total ration DM) on in vitro ruminal fermentation showed increased ruminal pH and ammonia concentration but lowered microbial protein. Acetic acid concentration was greatest with diets of 15 and 30% whole cottonseed, but propionate and total VFA concentrations were reduced by increasing whole cottonseed from 0 to 30%. In Experiment 2, neither niacin nor niacinamide (0, 100, 200, or 400 ppm) altered substantially fermenter pH or ammonia concentration. Both niacin and niacinamide increased synthesis of microbial protein. Acetate and propionate concentrations were not altered by treatment. Total VFA concentration tended to be lower as concentration of niacin and niacinamide increased. In Experiment 3, 28 Holstein cows were used to determine the effects of supplemental niacin on feed intake, milk yield, and composition. Cows were fed individually complete mixed diets ad libitum containing either: 1) 0; 2) .015; 3) .03; or 4) .06% niacin. There was a trend for lower milk fat test with niacin supplementation. Milk protein percentage was higher without niacin than with niacin at .015 or .03% in the diet, but daily milk and protein yields were higher with .06% versus .015% of niacin. Supplemental niacin did not affect casein nitrogen, lactose or minerals percentage, or concentrations of plasma glucose and insulin.

Effects of feeding waste milk from antibiotic-treated cows on growth, feed efficiency, and incidence of scours of dairy calves were studied. Twenty-four newborn Holstein heifer calves were assigned at random to one of the following treatments: 1) fresh normal milk, 2) fresh waste milk, 3) fermented waste milk, or 4) fermented waste milk plus sodium bicarbonate. Means for fat, crude protein, and total solids in normal milk (3.25, 3.05, and 11.84%) were lower than the same components for fresh waste milk (3.82, 3.42, and 12.59%) and fermented waste milk (4.02, 3.42, and 12.74%). Mean pH's for normal milk, fresh waste milk, and fermented waste milk were 6.6, 6.6, and 5.1. Calves were fed colostrum the first 3 days of life, and their respective treatment milk at 10% of body weight for 42 days. Dry calf feed was offered ad libitum beginning on day 4, and water was available at all times. Mean weight gains (kg) and ratios of average dry feed to gain (kg/kg) for the 42-day treatments were: 1) 19.2, .6; 2) 17.6, .6; 3) 19.6, .7; and 4) 20.1, .6. Incidence of scours was measured as number of days that scours were present per calf during the 42 days. Mean scour days for each group were: 1) 2.0, 2) 1.8, 3) 3.0, and 4) 4.8. There were no detrimental effects on calves fed fresh or fermented milk from cows treated with antibiotics. Addition of sodium bicarbonate did not affect acceptance of fermented milk by calves.

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