Acid-base status, renal function, water, and macromineral metabolism of dry cows fed diets differing in cation-anion difference.
Dietary cation-anion difference was defined as the summation of the milliequivalents of Na and K minus the sum of the milliequivalents of Cl and S per kilogram of DM. Twelve Holstein cows were used in a crossover experiment to compare the effects of changing the cation-anion difference of a diet based on haylage. Two cation-anion differences, 481.8 and 327.2 meq/kg, were compared. Increased dietary cation-anion difference had no significant effects on BW or intake and digestibility of DM, ADF, NDF, and N. The diet with a cation-anion difference of 481 meq/kg of DM increased apparent absorption of water and urine volume. Fecal excretion of Na and absorption and urinary excretion of S were increased by a cation-anion difference of 327 meq/kg of DM. Although blood concentrations were unaffected, lower dietary cation-anion difference reduced concentrations of H+ and HCO3- in urine and total urinary excretion of HCO3-. Plasma volume, packed cell volume, glomerular filtration rate, and effective renal plasma flow were unaffected by diet. Small changes in dietary cation-anion differences, even within the positive range, affected acid-base status and water metabolism of dry pregnant cows without affecting renal function or blood volume.
Delaquis
A M
AM
Department of Animal Science, McGill University, Ste-Anne de Bellevue, QC, Canada.
Block
E
E
D000042:Absorption; D000136:Acid-Base Equilibrium / Q000502:physiology*; D000818:Animals; D001639:Bicarbonates / Q000652:urine; D001834:Body Water / Q000378:metabolism*; D002118:Calcium / Q000008:administration & dosage / Q000378:metabolism; D002417:Cattle / Q000502:physiology*; D002712:Chlorides / Q000008:administration & dosage / Q000378:metabolism; D004032:Diet; D005260:Female; D007668:Kidney / Q000502:physiology*; D008274:Magnesium / Q000008:administration & dosage / Q000378:metabolism; D008903:Minerals / Q000378:metabolism*; D010758:Phosphorus / Q000008:administration & dosage / Q000378:metabolism; D011188:Potassium / Q000008:administration & dosage / Q000378:metabolism; D011247:Pregnancy; D012964:Sodium / Q000008:administration & dosage / Q000378:metabolism; D013455:Sulfur / Q000008:administration & dosage / Q000378:metabolism; D014867:Water / Q000008:administration & dosage
D001639:Bicarbonates; D002712:Chlorides; D008903:Minerals; D014867:Water; D010758:Phosphorus; D013455:Sulfur; D012964:Sodium; D008274:Magnesium; D011188:Potassium; D002118:Calcium