Effects of carbohydrates from citrus pulp and hominy feed on microbial fermentation in continuous culture

Eight dual-flow continuous-culture fermenters were used to evaluate the eff ect of neutral detergent-soluble carbohydrates (NDSC) on fermentation by ru minal microorganisms. Citrus pulp and hominy feed were added to a basal die t as sources of NDSC, with citrus pulp providing neutral detergent-soluble fiber (NDSF) in the form of pectic substances and with hominy feed in the f orm of starch. The basal diet contained 26.7% corn silage, 6.0% alfalfa hay and 3.8% cottonseed hulls on a DM basis. The dried citrus pulp diet contai ned on a DM basis 17.2% CP, 34.7% NDF, 33.7% NDSC, and 14.4% NDSF, whereas the hominy feed diet contained 17.9% CP, 33.2% NDF, 35.9% NDSC, and 8.8% ND SF. Organic matter, DM, and NDF and ADF digestion were not affected by sour ce of carbohydrate. Ammonia N concentration was greater (P < 0.05) for the hominy feed diet (14.2 mg/100 mL) than for the dried citrus pulp diet (9.3 mg/100 mL). Total N, nonammonia N, microbial N, and dietary N flows were no t affected by treatments; however, the efficiency of microbial protein synt hesis was greater (P = 0.055) for the dried citrus pulp diet than for the h ominy feed diet (30.6 vs 27.8 g of bacterial N/kg of OM truly digested). Re sults from this experiment indicate that NDSF from citrus pulp can provide similar sources of energy compared with starch from hominy feed to support ruminal microbial growth.