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Effects of pennycress meal on rumen fermentation using a continuous culture system
Two experiments were conducted to determine pennycress meal (PCM) RUP value and characterize effects on microbial fermentation. Four diets with increasing PCM, [control (0%, CON), 5.5% (TRT1), 11% (TRT2) and 16% (TRT3) PCM], were fed (40g/d) to continuous culture fermenters. Control diet had soybean meal (10%) as the major protein source. Corn (74%), soyhulls (10%), vitamins and minerals (2.6%) were similar across diets. We hypothesized increasing PCM concentration would increase RUP flow and not influence microbial fermentation. Diets and parameters analyzed were the same for both experiments. Diets were randomly distributed over fermenters (n = 24), acclimated for 4 d, and sampled over 3 d. Fermenters content was monitored 4 h post feeding for pH and analyzed for VFA (mM) and ammonia concentration (mM/dL). Data were analyzed as randomized complete design, using GLM procedure of SAS (SAS Inst. Inc., Cary, NC) with fermenter as experimental unit. For Exp. 1, propionate was greater (P = 0.04) for CON (13.68) compared to TRT1 (9.88). Valerate and isovalerate were greater (P < 0.05) for CON (1.35; 1.24) compared to TRT3 (1.14; 0.90). Acetate, butyrate, isobutyrate, total VFA, acetate:proprionate, pH and ammonia did not differ (P > 0.05) among diets. Organic matter digestibility was greater (P < 0.01) for CON (68.63) compared treatments (TRT1 61.87; TRT2 60.57; TRT3 59.50). Bacteria nitrogen (g/d) was greater (P = 0.03) for CON (0.60) compared to TRT3 (0.44). Microbial efficiency, nitrogen digestibility and RUP (g/d) did not differ (P > 0.05) among diets. For Exp. 2 acetate:propionate was greater (P = 0.01) for TRT3 (3.45) compared to CON (3.02). Acetate, propionate, butyrate , isobutyrate, isovalerate, valerate, total VFA, pH and ammonia did not differ (P > 0.05) among diets. Microbial efficiency, bacterial nitrogen, nitrogen digestibility, RUP did not differ (P > 0.05) among diets. In conclusion, increasing PCM concentration, did not increased RUP flow and had no effects on microbial efficiency.
Keywords: fermentation, pennycress meal, RUP