FLOWS OF NITROGEN AND AMINO-ACIDS IN DAIRY-COWS FED DIETS CONTAINING SUPPLEMENTAL FEATHER MEAL AND BLOOD MEAL

Four Holstein cows, fitted with ruminal and duodenal cannulas, were us ed to determine the effects of supplemental feather meal and blood mea l on ruminal fermentation and flows of N and AA to the duodenum. The b asal diet contained (DM basis) 9.9% chopped alfalfa hay, 39.7% corn si lage, 34.7% cracked corn, 8.2% corn starch, 2.1% vitamins and minerals , 4.4% casein, and 1% urea. A combination of feather meal and blood me al (3:1 on an N basis) was used to replace 0, 33, 67, and 100% of the casein and urea in the basal diet in a Latin square design. Intakes of DM, OM, and N were similar for all diets. Flows of total N, NAN, indi vidual AA, total AA, and total essential AA were unaltered as suppleme ntal feather meal plus blood meal increased. Flows of microbial N tend ed to decrease, but flow of non-ammonia, nonmicrobial N increased as s upplemental feather meal plus blood meal increased. Increased proporti ons of dietary feather plus blood meal decreased the proportions of IL e, Lys, Met, and Thr in duodenal digesta. Molar percentages of ruminal pH and VFA were unchanged, but concentrations of ruminal NH3 N decrea sed linearly as supplemental feather meal plus blood meal increased. F or the diets fed in this study, inclusion of one-third of the suppleme ntal protein from feather plus blood meal resulted in maximum flows of NAN and microbial N to the small intestine.