Experiments were conducted to determine mineral element levels in feedstuffs, animal wastes and tissues from cattle fed broiler litter or cattle waste. Heifers fed 30% broiler litter ensiled with corn forage performed as well as heifers fed corn silage and soybean meal but performance tended to be lower than for heifers fed corn-litter silage and soybean meal in a 20l-day feeding trial. No differences were found in carcass quality and yield grades. Feedlot performance was very low for cattle fed corn silage and no protein supplement. Feeding broiler litter to heifers did not adversely affect the eating quality of roasts from these heifers as measured subjectively by a taste panel and shear devices. Copper (593 ppm) and arsenic (75.9 ppm) levels were high in broiler litter, compared to other ruminant feedstuffs. Following a 24-hour withdrawal, heifers were slaughtered and liver, muscle, fat and kidney samples were taken. Liver copper reflects high dietary copper intakes in litter fed heifers (P <.01). Arsenic in the kidney and fat was higher in litter-fed heifers. Bromine was lower (P <.05) in liver, kidney, muscle and fat of litter-fed heifers. In two successive cattle finishing trials, a 16% cattle waste ration was compared to a conventional feedlot ration. Control steers in trial I outgained (1.31 kg/day) waste fed steers (1.14 kg/day), but in trial II gains were higher for the waste fed steers (1.41 vs 1.54 kg/day). In trial I selenium was higher (P <.05) in livers of steers fed waste. In trial II lead content was higher (P <.05) in fat of waste fed cattle and liver copper was higher (P <.05) in conventionally-fed steers. In a long term experiment, currently in its sixth year, cows were wintered on hay, 804 litter and 20% corn grain with and without supplemental copper. Liver biopsies of the cows were taken in December and April, the beginning and end of the wintering period. Average copper levels in the wintering rations were 15.9, 412.6 and 595.6 ppm, dry basis, respectively. Liver biopsies taken in December and April for litter-fed cattle were higher (P <.01) in copper than livers of cows fed hay. Respective April and December liver copper values were: hay, 34.5 and 27.03; corn-litter, 757.3 and 195.7; corn-litter-copper, 964.4 and 218.9 ppm, dry basis. Liver arsenic levels were similar after the grazing season but increased dramatically over the wintering period. Waste samples from broilers, caged layers, cattle and swine from several regions in the United States were analyzed. Litter arsenic and copper values were 54 and 441 ppm, respectively. Dried poultry waste varied in ash, crude protein, cadmium and selenium. Aluminum, cadmium and copper content of cattle waste was higher for all samples than values reported in the literature. Swine waste had an average crude protein content of 23% and varied in cadmium and selenium. / Ph. D.