| Effects of particle size and dry matter content of a total mixed ration on intraruminal equilibration and net portal flux of volatile fatty acids in lactating dairy cows. | |
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MedLine Citation:
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PMID: 20723696 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Effects of physical changes in consistency of ruminal contents on intraruminal equilibration and net portal fluxes of volatile fatty acids (VFA) in dairy cows were studied. Four Danish Holstein cows (121+/-17 d in milk, 591+/-24 kg of body weight, mean+/-SD) surgically fitted with a ruminal cannula and permanent indwelling catheters in the major splanchnic blood vessels were used. The experimental design was a 4x4 Latin square with a 2x2 factorial design of treatments. Treatments differed in forage (grass hay) particle size (FPS; 3.0 and 30 mm) and feed dry matter (DM) content of the total mixed ration (44.3 and 53.8%). The feed DM did not affect chewing time, ruminal variables, or net portal flux of VFA. However, decreasing the FPS decreased the overall chewing and rumination times by 151+/-55 and 135+/-29 min/d, respectively. No effect of the reduced chewing time was observed on ruminal pH or milk fat percentage. Cows maintained average ventral ruminal pH of 6.65+/-0.02, medial ruminal pH of 5.95+/-0.04, and milk fat of 4.42+/-0.12% with chewing time of 28.0+/-2.1 min/kg of DM when fed short particles. The medial ruminal pool of wet particulate matter was decreased by 10.53+/-2.29 kg with decreasing FPS, thereby decreasing the medial pool of total VFA, acetate, propionate, butyrate, isobutyrate, and isovalerate by 1,143+/-333, 720+/-205, 228+/-69, 140+/-51, 8.0+/-2.3, and 25.2+/-5.6 mmol, respectively. Ventral pool variables were not affected by treatments. Relatively large intraruminal differences of VFA concentrations and pH between the ventral and medial pools were observed, VFA concentrations being largest and pH being the lowest medially. This indicates that the ruminal mat acts as a barrier retaining VFA. The effects of reduced FPS were limited to the VFA pool sizes of the mat, leaving ruminal pH, ruminal VFA concentrations, and net portal flux of VFA unaffected. Consequently reduced FPS affected the intraruminal equilibration of VFA between mat and ventral rumen with an estimated turnover rate of isobutyrate increasing from 66+/-3%/h with long particles to 81+/-3%/h [corrected] with short particles. The estimated ruminal fluid flow and therefore intraruminal VFA transport between medial and ventral phase was not affected by the FPS. In conclusion, the ruminal mat pool of VFA was proportional to the size of the mat and the only detected effects of decreasing FPS were decreasing the mat size and an increasing turnover of the mat pool of VFA. |
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Authors:
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A C Storm; N B Kristensen |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of dairy science Volume: 93 ISSN: 1525-3198 ISO Abbreviation: J. Dairy Sci. Publication Date: 2010 Sep |
Date Detail:
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Created Date: 2010-08-20 Completed Date: 2010-11-30 Revised Date: 2011-01-12 |
Medline Journal Info:
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Nlm Unique ID: 2985126R Medline TA: J Dairy Sci Country: United States |
Other Details:
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Languages: eng Pagination: 4223-38 Citation Subset: IM |
Copyright Information:
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Copyright (c) 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved. |
Affiliation:
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Department of Animal Health and Bioscience, Faculty of Agricultural Sciences, Aarhus University, DK-8830 Tjele, Denmark. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animal Feed*
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analysis Animals Cattle / metabolism*, physiology Diet / veterinary* Eating / physiology Fatty Acids, Volatile / analysis, metabolism* Female Gastric Juice / chemistry Lactation / physiology Milk / secretion Particle Size Rumen / metabolism, physiology* |
| Chemical | |
Reg. No./Substance:
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0/Fatty Acids, Volatile |
| Comments/Corrections | |
Erratum In:
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J Dairy Sci. 2011 Jan;94(1):532-5 |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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