THE COMPARISON OF 2 FORMS OF SODIUM AND POTASSIUM AND CHLORIDE VERSUSSULFUR IN THE DIETARY CATION-ANION DIFFERENCE EQUATION - EFFECTS ON ACID-BASE STATUS AND MINERAL BALANCE IN SEDENTARY HORSES
La. Baker et al., THE COMPARISON OF 2 FORMS OF SODIUM AND POTASSIUM AND CHLORIDE VERSUSSULFUR IN THE DIETARY CATION-ANION DIFFERENCE EQUATION - EFFECTS ON ACID-BASE STATUS AND MINERAL BALANCE IN SEDENTARY HORSES, Journal of equine veterinary science, 18(6), 1998, pp. 389-395
Six mature geldings were randomly assigned treatments within a 6 x 6 L
atin square design experiment to study the effects of the Dietary Cati
on-Anion Difference equation (DCAD) on acid-base status and mineral ba
lance in sedentary horses. Dietary Cation-Anion Difference was calcula
ted as: meg ((Na + K) - (Cl + S))/kg diet DM. High (H) diets were form
ulated with the addition of sodium citrate (H:NaC), sodium bicarbonate
(H:NaB), potassium citrate (H:KC), and potassium bicarbonate (H:KB).
Low (L) diets were formulated with the addition of magnesium sulfate (
L:S) and ammonium chloride (L:Cl). Experimental diets consisted of a p
elleted base concentrate fed in a 60:40 ratio with native prairie gras
s hay, and were fed for a 12-day adjustment period followed by a 72-h
sample collection period. Post-feeding venous blood samples were analy
zed for the determination of pH and HCO3. Post-feeding urine samples w
ere analyzed for the determination of urine pH. Representative samples
of feed, feces, and urine were analyzed for mineral content and appar
ent mineral balances were calculated by difference. Horses consuming L
:Cl and L:S had lower (P < .05) urine pH values as compared to horses
consuming all H diets at all intervals measured. Horses consuming L:Cl
had lower (P <.05) blood pH values as compared to those consuming all
H diets at 10 of 12 intervals measured. Horses consuming L:CI had low
er (P <.05) blood HCO, values as compared to those consuming L:S at 6
of 12 intervals measured, and had lower (P < .05) HCO3 values as compa
red to those consuming all H diets at all intervals measured. Horses c
onsuming H:NaB and H:NaC excreted more Na in the urine (P < .05) and f
eces (P < .05) as compared to those consuming all other diets. Horses
consuming H:KC and H:KB excreted more (P <.05) K in the urine, and had
a lower (P <.05) apparent daily K balance as compared to those consum
ing all other diets. Horses consuming L:Cl excreted more (P <.05) Clin
the urine as compared to those consuming all other diets. Horses cons
uming L:S had greater (P <.05) daily fecal excretion of S as compared
to horses consuming all other diets. Horses consuming L:Cl had a lower
(P <.05) apparent daily Ca balance as compared to those consuming all
other diets, while horses consuming L:S had a lower (P <.05) apparent
daily Ca balance as compared to those consuming H:NaB. These data ind
icate that the feeding of excess strong cations in relation to anions,
regardless of the fed form (bicarbonate or citrate), results in simil
ar increases in plasma and urine alkalinity. Also, these data indicate
that S needs a modifying coefficient in the DCAD equation, as it does
not appear to be as acidogenic as Cl in sedentary horses.