INFLUENCE OF CRAMBE MEAL AS A PROTEIN-SOURCE ON INTAKE, SITE OF DIGESTION, RUMINAL FERMENTATION, AND MICROBIAL EFFICIENCY IN BEEF STEERS FED GRASS HAY

Four ruminally and duodenally cannulated beef steers (558 +/- 37 kg) w ere arranged in a 4 x 4 Latin square to evaluate the influence of cram be meal as a protein source on intake, digestion, and microbial effici ency. Steers were offered chopped (10.2 cm) brome hay (6.2% CP) for ad libitum consumption and one of four supplements. Protein sources used were soybean and crambe meals (CM). Protein sources were blended to p rovide four levels of supplemental CM protein (0, 33, 67, and 100%). P rotein supplements were fed to provide similar amounts of protein and energy. Amounts of supplements fed were 831, 885, 950: and 996 g of DM /steer daily for 0, 33, 67, and 100% CM treatments, respectively. Cram be meal represented 0, 2.00, 3.83, and 5.88% of the DM intake for resp ective treatments. Steers were allowed a 21-d adaptation to diets befo re each collection period. Supplements were offered at 0800 and forage at 0830. Crambe meal had no influence (P > .10) on forage and total D M intake (grams/kilogram of BW). Apparent total tract, ruminal, and po struminal digestion of OM, NDF, ADF, and N were unaffected (P > .10) b y CM supplementation. True ruminal N digestion tended (P < .19) to inc rease quadratically with increasing proportion of CM as a protein sour ce. Total nonbacterial and bacterial N flows at the duodenum, as well as microbial efficiency, were unaffected (P > .10) by treatment. Total ruminal VA concentrations were reduced (linearly; P < .10) by the add ition of CM as a protein source. No other differences (P > .10) were n oted in ruminal fermentation data. Rate of in situ disappearance of po tentially degradable NDF and CP digestion (percentage/hour) were unaff ected (P > .10) by CM supplementation. Readily degradable and slowly d egradable forage CP fractions (Fraction A and Fraction B, respectively ) were unaffected (P > .10) by addition of CM. These data indicate tha t CM can be used as a protein source in high-forage diets for cattle.