Coffee grounds. I. Effects of coffee grounds on ration digestibility and diuresis in cattle, on in vitro rumen fermentation, and on rat growth.

Holstein steers were used to compare rations in which coffee grounds replaced grain at rates of 0, 5, 10, or 20%. The coffee grounds analyzed (%) dry matter 91.1, protein 11.8, fat 23.1, fiber 42.5, ash .7, and caffeine .13. Digestibility coefficients for dry matter, crude protein, and energy decreased, and ether extract increased progressively as concentrations of coffee grounds in the ration were increased. There was a significant decrease in nitrogen retention and utilization when the rations contained 10 or 20% coffee grounds. Coffee grounds depressed feed intake, increased urinary output, and increased water intake (based on dry matter intake). Coffee grounds caused diuresis and renal, urethral, and bladder irritation. Adding coffee grounds up to 35% of the substrate did not depress rumen microbial fermentation, as measured by in vitro gas production. Weight gain of rats fed rations containing 22.5% untreated coffee grounds was reduced significantly. Water extraction removed some undersirable factors in coffee grounds for rats, and ether extraction removed most of them. Incremental additions of coffee oil (1, 3, or 5%) to the basal diet resulted in incremental decreases in rat weight gain.