HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: jas.2007-0036v1 85/9/2222    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Las, J. E. Articles by McBride, B. W. Search for Related Content PubMed PubMed Citation Articles by Las, J. E. Articles by McBride, B. W.

Effects of dietary strong acid anion challenge on regulation of acid-base balance in sheep¹

J. E. Las^*, N. E. Odongo^*, M. I. Lindinger^,2, O. AlZahal^*, A. K. Shoveller^*, J. C. Matthews and B. W. McBride^*

^* Department of Animal and Poultry Science, and and Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, Canada, N1G 2W1; and and Department of Animal and Food Sciences, University of Kentucky, Lexington 40546

² Corresponding author: nodongo{at}uoguelph.ca

The acid-base status of the extracellular fluid is directly affected by the concentrations of strong basic cations and strong acid anions that are absorbed into the bloodstream from the diet. The objective of this study was to develop and characterize a model for dietary acid challenge in sheep by decreasing the dietary cation-anion difference (DCAD) using NutriChlor (HCl-treated canola meal), an anionic feed supplement. Ten fully fleeced sheep (Rideau-Arcott, 54.3 ± 6.7 kg of BW) were fed either a control supplement [200 g/d of canola meal, DCAD = 184 mEq/kg of DM, calculated as (Na⁺ + K⁺) – (Cl^– + S^2–)] or an anionic supplement (AS; 200 g/d of NutriChlor, DCAD = –206 mEq/kg of DM) offered twice daily at 0700 and 1100 in a randomized complete block design. The sheep were individually housed and limit-fed a basal diet of dehydrated alfalfa pellets (22% CP and 1.2 Mcal of NE_g/kg, DM basis) at 1.1 kg of DM/d offered twice daily at 1000 and 1300. Two days before the beginning of the experiment, the sheep were fitted with vinyl catheters (0.86-mm i.d., 1.32-mm o.d.) in the left jugular vein to facilitate blood sampling. Blood and urine samples were obtained daily from 1100 to 1130 on d 1 through 9 and at 0700, 1000, 1300, 1600, and 1900 on d 10. Blood was analyzed for hematocrit, plasma pH, gases, strong ions, and total protein. Urine samples were analyzed for pH. The AS induced a nonrespiratory acid-base disturbance associated with lower (P < 0.05) plasma pH (7.47 vs. 7.39), lower (P < 0.05) urine pH (8.13 vs. 6.09), and lower (P < 0.05) strong ion difference (42.5 vs. 39.5). The AS reduced (P < 0.05) the concentration of plasma glucose, base excess, and bicarbonate and increased (P < 0.05) the concentration of K⁺ and Cl^–. Lowering DCAD increased (P < 0.05) Ca²⁺ concentrations in plasma by 13%. In conclusion, this dietary model successfully induced a significant acid-base disturbance in sheep. Although the acidifying effects of negative DCAD in the diet may have short-term prophylactic effects of elevating the concentration of Ca²⁺ in plasma, negative DCAD may have detrimental effects on acid-base balance.

Key Words: acid-base homeostasis • anionic supplement • physicochemical approach • sheep