Effect of anionic salts and potassium intake on some blood and urine minerals and acid-base balance of dry pregnant cows on grass silage based feeding
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University of Helsinki, Department of Animal Science, FIN-00014 Helsinki, Finland
University of Helsinki, Department of Clinical Veterinary Sciences, Hämeentie 57, P.O. Box 6, FIN-00581 Helsinki, Finland
Publication date: 2001-01-22
J. Anim. Feed Sci. 2001;10(1):57–71
Twenty-one Ayshire cows were randomly assigned to one of three diets to determine the effect of an anionic diet and high potassium (K) intake on mineral metabolism, acid-base status and feed intake of dairy cows fed grass silage based diets during the dry period. Dietary cation-anion balance (DCAB), calculated as milliequivalents [(Na+ + K+ ) - (CI- + S2-)], for high DCAB (control), high DCAB + K-supplement (added as KHCO3) and low DCAB treatments were +298, +571 and +107 mEq/kg DM, respectively. Dietary magnesium (Mg) content, equivalent to a daily Mg intake of 33 g, was on average 0.4% (in a DM basis). Cows received grass silage (5.2 kg DM), hay (0.9 kg DM) and concentrate mixture (2.7 kg DM) until calving. Blood and urine samples were collected 4, 3, 2 and 1 week before the expected calving date, at calving, the day and 1 week after calving. Only urinary pH was significantly affected by a low DCAB prepartum. K supplementation decreased fractional excretion of Mg and Na in the urine and significantly increased prepartum urinary K excretion. A dietary K concentration of 34 g/kg DM coupled with a high Mg intake of 4 g/kg DM in the prepartum diet may negatively effect Mg metabolism after parturition.
Prediction of urinary and blood pH in non-lactating dairy cows fed anionic diets
M Spanghero
Animal Feed Science and Technology