title: Effects of Partial Replacement of Corn with Glycerin on Ruminal Fermentation in a Dual-Flow Continuous Culture System.
abstract: The objective of this study was to evaluate the effects of partially replacing dry ground corn with glycerin on ruminal fermentation using a dual-flow continuous culture system. Six fermenters (1,223 ± 21 ml) were used in a replicated 3x3 Latin square arrangement with three periods of 10 d each, with 7 d for diet adaptation and 3 d for sample collections. All diets contained 75% concentrate and three dietary glycerin levels (0, 15, and 30% on dry matter basis), totaling six replicates per treatment. Fermenters were fed 72 g of dry matter/d equally divided in two meals/d, at 0800 and 2000 h. Solid and liquid dilution rates were adjusted daily to 5.5 and 11%/h, respectively. On d 8, 9, and 10, samples of 500 ml of solid and liquid digesta effluent were mixed, homogenized, and stored at -20°C. Subsamples of 10 ml were collected and preserved with 0.2 mL of a 50% H2SO4 solution for later determination of NH3-N and volatile fatty acids. Microbial biomass was isolated from fermenters for chemical analysis at the end of each experimental period. Data were analyzed using the MIXED procedure in SAS with α = 0.05. Glycerin levels did not affect apparent digestibility of DM (PLin. = 0.13; PQuad. = 0.40), OM (PLin. = 0.72; PQuad. = 0.15), NDF (PLin. = 0.38; PQuad. = 0.50) and ADF (PLin. = 0.91; PQuad. = 0.18). Also, glycerin inclusion did not affect true digestibility of DM (PLin. = 0.35; PQuad. = 0.48), and OM (PLin. = 0.08; PQuad. = 0.19). Concentrations of propionate (P < 0.01) and total volatile fatty acids (P < 0.01) increased linearly and concentrations of acetate (P < 0.01), butyrate (P = 0.01), iso-valerate (P < 0.01), and total branched-chain volatile fatty acids, as well as the acetate: propionate ratio (P < 0.01) decreased with glycerin inclusion. Linear increases on NH3-N concentration in digesta effluent (P < 0.01) and on NH3-N flow (P < 0.01) were observed due to glycerin inclusion in the diets. Crude protein digestibility (P = 0.04) and microbial N flow (P = 0.04) were greater in the control treatment compared with the other treatments and responded quadratically with glycerin inclusion. Furthermore, the inclusion of glycerin linearly decreased (P = 0.02) non-ammonia N flow. Glycerin levels did not affect the flows of total N (PLin. = 0.79; PQuad. = 0.35), and dietary N (PLin. = 0.99; PQuad. = 0.07), as well as microbial efficiency (PLin. = 0.09; PQuad. = 0.07). These results suggest that partially replacing dry ground corn with glycerin may change ruminal fermentation, by increasing total volatile fatty acids, and propionate concentration without affecting microbial efficiency, which may improve glucogenic potential of beef cattle diets.
authors.affiliation: Department of Agriculture, Nutrition, and Veterinary Sciences, University of Nevada, Reno, Nevada, United States of America.|Department of Animal Sciences, Federal University of Viçosa, Viçosa, Minas Gerais, Brazil.
authors.forename: Pedro
authors.initials: P
authors.lastname: Del Bianco Benedeti
authors.affiliation: Department of Agriculture, Nutrition, and Veterinary Sciences, University of Nevada, Reno, Nevada, United States of America.
authors.forename: Lorrayny
authors.initials: L
authors.lastname: Galoro da Silva
authors.affiliation: Department of Agriculture, Nutrition, and Veterinary Sciences, University of Nevada, Reno, Nevada, United States of America.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Marostegan de Paula
authors.affiliation: Department of Agriculture, Nutrition, and Veterinary Sciences, University of Nevada, Reno, Nevada, United States of America.
authors.forename: Teshome
authors.initials: T
authors.lastname: Shenkoru
authors.affiliation: Department of Animal Sciences, Federal University of Viçosa, Viçosa, Minas Gerais, Brazil.
authors.forename: Marcos Inácio
authors.initials: MI
authors.lastname: Marcondes
authors.affiliation: Department of Agriculture, Nutrition, and Veterinary Sciences, University of Nevada, Reno, Nevada, United States of America.|Department of Animal Sciences, Maringá State University, Maringá, Paraná, Brazil.
authors.forename: Hugo Fernando
authors.initials: HF
authors.lastname: Monteiro
authors.affiliation: Department of Agriculture, Nutrition, and Veterinary Sciences, University of Nevada, Reno, Nevada, United States of America.
authors.forename: Brad
authors.initials: B
authors.lastname: Amorati
authors.affiliation: Department of Agriculture, Nutrition, and Veterinary Sciences, University of Nevada, Reno, Nevada, United States of America.
authors.forename: Yenling
authors.initials: Y
authors.lastname: Yeh
authors.affiliation: Department of Geological Sciences & Engineering, University of Nevada, Reno, Nevada, United States of America.
authors.forename: Simon Roger
authors.initials: SR
authors.lastname: Poulson
authors.affiliation: Department of Agriculture, Nutrition, and Veterinary Sciences, University of Nevada, Reno, Nevada, United States of America.
authors.forename: Antonio Pinheiro
authors.initials: AP
authors.lastname: Faciola
mesh_terms: D000641:Ammonia / Q000737:chemistry; D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D018533:Biomass; D002417:Cattle; D018929:Cell Culture Techniques; D003470:Culture Media; D004032:Diet; D004063:Digestion; D005232:Fatty Acids, Volatile / Q000737:chemistry; D005285:Fermentation; D005990:Glycerol / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009584:Nitrogen / Q000737:chemistry; D012417:Rumen / Q000378:metabolism*; D003313:Zea mays / Q000737:chemistry*
chemical_list: D003470:Culture Media; D005232:Fatty Acids, Volatile; D000641:Ammonia; D009584:Nitrogen; D005990:Glycerol