title: Effects of Static or Oscillating Dietary Crude Protein Levels on Fermentation Dynamics of Beef Cattle Diets Using a Dual-Flow Continuous Culture System.
abstract: The objective of this study was to evaluate the effects of increasing dietary crude protein (CP) levels and also comparing the effects of static versus oscillating dietary CP on ruminal nutrient digestibility, ruminal fermentation, nitrogen (N) metabolism, and microbial efficiency in beef cattle diets using a dual-flow continuous culture system. Eight fermenters (1,223 ± 21 mL) were used in a replicated 4 x 4 Latin square design with periods lasting 12 d each (8 d for adaptation and 4 d for sampling). Dietary treatments were: 1) 10% CP, 2) 12% CP, 3) 14% CP, and 4) 10 and 14% CP diets oscillating at 48-h intervals. Experimental diets consisted of 50% orchard hay and 50% concentrate. Fermenters were fed 72 g/d and solid and liquid dilution rates were adjusted to 5.5 and 11%/h, respectively. Data were analyzed using the MIXED procedure in SAS with α = 0.05. Apparent and true ruminal digestibilities of dry matter and organic matter were not affected (P > 0.05) by increasing dietary CP, nor by oscillating dietary CP. Total volatile fatty acids concentration and molar proportions of acetate, propionate, butyrate, valerate, iso-butyrate and iso-valerate were not affected (P > 0.05) by increasing or oscillating dietary CP. Ruminal NH3-N concentration increased linearly (P < 0.01) in response to increasing dietary CP. Total N, non-ammonia N, and rumen undegraded protein flows did not differ among treatments or between oscillating dietary CP and static 12% CP. Microbial N and NH3-N flows and microbial efficiency did not differ when comparing oscillating versus static CP (P > 0.05). However, there was a quadratic effect (P < 0.05) for these variables when dietary CP was increased. These results indicate that either ruminal microorganisms do not respond to oscillating CP levels or are capable of coping with 48-h periods of undernourishment.
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: Paloma de Melo
authors.initials: PM
authors.lastname: Amaral
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: Lays Débora Silva
authors.initials: LD
authors.lastname: Mariz
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 Del Bianco
authors.initials: PD
authors.lastname: Benedeti
authors.affiliation: Department of Agriculture, Nutrition, and Veterinary Sciences, University of Nevada, Reno, Nevada, United States of America.
authors.forename: Lorrayny Galoro da
authors.initials: LG
authors.lastname: Silva
authors.affiliation: Department of Agriculture, Nutrition, and Veterinary Sciences, University of Nevada, Reno, Nevada, United States of America.
authors.forename: Eduardo Marostegan de
authors.initials: EM
authors.lastname: Paula
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: Teshome
authors.initials: T
authors.lastname: Shenkoru
authors.affiliation: Department of Animal Sciences, Federal University of Bahia, Salvador, Bahia, Brazil.
authors.forename: Stefanie Alvarenga
authors.initials: SA
authors.lastname: Santos
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.identifier: http://orcid.org/0000-0003-0935-6233
authors.initials: AP
authors.lastname: Faciola
mesh_terms: D000641:Ammonia / Q000378:metabolism; D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena / Q000502:physiology; D000818:Animals; D019149:Bioreactors; D002417:Cattle; D004032:Diet / Q000662:veterinary*; D004044:Dietary Proteins / Q000008:administration & dosage / Q000032:analysis* / Q000737:chemistry; D019587:Dietary Supplements; D004063:Digestion / Q000502:physiology*; D005227:Fatty Acids / Q000378:metabolism; D005285:Fermentation; D009584:Nitrogen / Q000378:metabolism; D012417:Rumen / Q000378:metabolism*
chemical_list: D004044:Dietary Proteins; D005227:Fatty Acids; D000641:Ammonia; D009584:Nitrogen