| Effects of dietary cation-anion difference on ruminal metabolism and blood acid-base regulation in dairy cows receiving 2 contrasting levels of concentrate in diets. | |
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MedLine Citation:
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PMID: 20723694 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Dietary cation-anion difference [DCAD=Na+K-Cl in mEq/kg of dry matter (DM)] increases DM intake (DMI) in cows fed diets containing rapidly degraded starch. Increased DMI of diets containing rapidly degraded starch could potentially exacerbate subacute acidosis. The objective of this study was to determine metabolic effects of increasing DCAD in low and high starch diets. Six cannulated Holstein cows were blocked into 2 groups of 3 cows and assigned to two 3 x 3 Latin squares in a split-plot design. Each group received a level of concentrate at either 20 or 40% on a DM basis. The diet containing 20% concentrate supplied 4% rapidly degraded starch, whereas the diet containing 40% concentrate supplied 22% rapidly degraded starch. Diets in each square were formulated to provide a DCAD of 0, 150, or 300 mEq/kg of DM. The 3 values were obtained by manipulating Na and Cl contents. Increasing the proportion of rapidly degraded starch decreased rumen pH and the acetate to propionate ratio but did not affect digestibility, blood acid-base status, pH of urine, and strong ion excretion. Increasing DCAD increased DMI, the effect being higher when the cows were fed the 40% concentrate diet. Increasing DCAD did not affect mean ruminal pH, molar proportion of VFA, and fiber digestibility; reduced the range of rumen pH decrease during the meal in cows fed the 40% concentrate diet; and strongly increased blood pH and blood HCO3 concentration. Increasing DCAD increased urine pH and modified the urinary excretion of minerals. With low DCAD, 70% of Cl and only 16% of Na were excreted in urine whereas with high DCAD, 33% of Cl and 53% of Na were excreted. These results suggest that DMI of cows fed diets rich in rapidly degraded starch and low DCAD was limited to maintain the blood pH in a physiological range. Increasing DCAD allowed the cows to increase DMI because of the ability of positive DCAD to maintain blood acid-base status. A localized rumen buffering effect could not be excluded and could be linked with a higher amount of HCO3 recycled into the rumen. Main mechanisms involved in regulating blood pH might be renal excretion of protons and strong ions and renal HCO3 reabsorption. |
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Authors:
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E Apper-Bossard; P Faverdin; F Meschy; J L Peyraud |
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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: - |
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: 4196-210 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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INRA, UMR1080 Dairy Production, F-35000 Rennes, France. e.bossard@groupe-esa.com |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Acid-Base Equilibrium
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physiology* Animal Feed / analysis Animals Bicarbonates / blood Cattle / metabolism*, physiology Diet / veterinary* Dietary Fiber / pharmacology Eating / physiology Energy Metabolism / physiology Feces / chemistry Female Hydrogen-Ion Concentration Milk / secretion Rumen / metabolism* Urodynamics / physiology |
| Chemical | |
Reg. No./Substance:
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0/Bicarbonates |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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