Effects of varying ruminally undegradable protein supplementation on forage digestion, nitrogen metabolism, and urea kinetics in Nellore cattle fed low-quality tropical forage

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dc.contributor.author Batista, E. D.
dc.contributor.author Detmann, E.
dc.contributor.author Titgemeyer, Evan C.
dc.contributor.author Valadares, S. C.
dc.contributor.author Valadares, R. F. D.
dc.contributor.author Prates, L. L.
dc.contributor.author Renno, L. N.
dc.contributor.author Paulino, M. F.
dc.date.accessioned 2016-09-20T17:40:42Z
dc.date.available 2016-09-20T17:40:42Z
dc.identifier.uri http://hdl.handle.net/2097/34107
dc.description Citation: Batista, E. D., Detmann, E., Titgemeyer, E. C., Valadares, S. C., Valadares, R. F. D., Prates, L. L., . . . Paulino, M. F. (2016). Effects of varying ruminally undegradable protein supplementation on forage digestion, nitrogen metabolism, and urea kinetics in Nellore cattle fed low-quality tropical forage. Journal of Animal Science, 94(1), 201-216. doi:10.2527/jas2015-9493
dc.description.abstract Effects of supplemental RDP and RUP on nutrient digestion, N metabolism, urea kinetics, and muscle protein degradation were evaluated in Nellore heifers (Bos indicus) consuming low-quality signal grass hay (5% CP and 80% NDF, DM basis). Five ruminally and abomasally cannulated Nellore heifers (248 +/- 9 kg) were used in a 5 x 5 Latin square. Treatments were the control (no supplement) and RDP supplementation to meet 100% of the RDP requirement plus RUP provision to supply 0, 50, 100, or 150% of the RUP requirement. Supplemental RDP (casein plus NPN) was ruminally dosed twice daily, and RUP supply (casein) was continuously infused abomasally. Jugular infusion of [(NN)-N-15-N-15]-urea with measurement of enrichment in urine was used to evaluate urea kinetics. The ratio of urinary 3-methylhistidine to creatinine was used to estimate skeletal muscle protein degradation. Forage NDF intake (2.48 kg/d) was not affected (P >= 0.37) by supplementation, but supplementation did increase ruminal NDF digestion (P < 0.01). Total N intake (by design) and N retention increased (P < 0.001) with supplementation and also linearly increased with RUP provision. Urea entry rate and gastrointestinal entry rate of urea were increased by supplementation (P < 0.001). Supplementation with RUP linearly increased (P = 0.02) urea entry rate and tended (P = 0.07) to linearly increase gastrointestinal entry rate of urea. Urea use for anabolic purposes tended (P = 0.07) to be increased by supplementation, and RUP provision also tended (P = 0.08) to linearly increase the amount of urea used for anabolism. The fraction of recycled urea N incorporated into microbial N was greater (P < 0.001) for control (22%) than for supplemented (9%) heifers. Urinary 3-methylhistidine: creatinine of control heifers was more than double that of supplemented heifers (P < 0.001). Control heifers reabsorbed a greater (P < 0.001) fraction of urea from the renal tubule than did supplemented heifers. Overall, unsupplemented heifers had greater mobilization of AA from myofibrillar protein, which provided N for urea synthesis and subsequent recycling. Supplemental RUP, when RDP was supplied, not only increased N retention but also supported increased urea N recycling and increased ruminal microbial protein synthesis.
dc.relation.uri https://doi.org/10.2527/jas2015-9493
dc.rights Copyright © 2016. American Society of Animal Science.
dc.rights.uri http://www.sherpa.ac.uk/romeo/issn/0021-8812/
dc.subject Bos Indicus
dc.subject Cattle
dc.subject Muscle Degradation
dc.subject Protein Supplementation
dc.subject Tropical Forage
dc.subject Urea Recycling
dc.title Effects of varying ruminally undegradable protein supplementation on forage digestion, nitrogen metabolism, and urea kinetics in Nellore cattle fed low-quality tropical forage
dc.type Article
dc.date.published 2016
dc.citation.doi 10.2527/jas2015-9493
dc.citation.epage 216
dc.citation.issn 0021-8812
dc.citation.issue 1
dc.citation.jtitle Journal of Animal Science
dc.citation.spage 201
dc.citation.volume 94
dc.description.embargo 2017-01
dc.contributor.authoreid etitgeme


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