Role of sulfur and chloride in the dietary cation-anion balance equation for lactating dairy cattle.

Abstract

Ten Holstein cows averaging 120 d in lactation were arranged in replicated 5 x 5 Latin squares with 3-wk periods to evaluate the role of sulfur (S) in the dietary cation-anion balance equation. Diets were based on corn silage in Exp. 1 and sorghum silage in Exp. 2. Supplemental S and chloride (Cl) from the double sulfate of potassium and magnesium and CaCl2 were used to manipulate dietary cation-anion balance from 0 to +30 meq when expressed as meq [(Na + K)-(Cl + S)]/100 g diet DM and from +19 to +49 meq when expressed as meq [(Na + K)-Cl]/100 g diet DM. Blood pH was not affected by cation-anion balance, although both S and Cl supplementation tended to lower pH. Blood HCO3- and urine pH decreased and plasma calcium (Ca) and urinary Ca excretion increased as anion was added to the diet. Milk fat production tended to be increased by the low S supplementation. Dietary Cl and S had similar effects on acid-base status. Therefore, we suggest that S be included with Cl in the dietary cation-anion balance equation for lactating dairy cows as follows: meq [(Na + K)-(Cl + S)]/100 g diet DM. Although response of acid-base status to S and Cl was similar, as more data comparing the acidogenicity of S vs Cl become available, it may be necessary to include a modifying coefficient for S in the equation to adjust for differences between S and Cl in acid-generating potential. This coefficient may be further dependent on the dietary source of S.

Effect of dietary cation–anion difference on ruminal metabolism, total apparent digestibility, blood and renal acid–base regulation in lactating dairy cows

“…Similarly, Tucker et al (1992) observed that cows fed anionic diets in prepartum had higher blood concentration of iCa than cows fed cationic diets. Similar results were also reported by Tucker et al (1991) and Wu et al (2008). The increase of blood concentration of Ca can be a metabolic response to pH reduction of cellular and transcellular fluids, which stimulates the production of hormones PTH and 1.25 (OH 2 )D 3 , and depresses the action of calcitonin.…”

“…The table with ingredients proportion and chemical composition of experimental diets was described in detail in a companion paper (Martins et al, 2015). The DCAD levels were calculated based on Tucker et al (1991) using the formula: mEq/kg of DM = [(% Na in DM/0.023)…”

Influence of dietary cation-anionic difference on hematobio chemical profile, mineral metabolism, post-partum reproductive and productive performance of Hariana cows

“…Similarly, Tucker et al (1988b) also reported a linear increase in plasma Cl -concentration with decrease in the DCAD levels (+20 to -10 meq/kg of DM). Increased plasma Cl -concentration in low DCAD fed cows might be due to high intake of CaCl 2, used for reduction of dietary DCAD level as reported by Tucker et al (1991). The plasma Na, K and Cl level in present finding is closely associated with increased blood pH in cows fed on high DCAD diet.…”

The relationship between cation-anion differences in dairy cow diets and some blood indices levels and milk composition

“…The feed mineral composition was determined (AOAC, 1995). DCAD was calculated using the formula of Tucker et al (1991) (meqK+meqNa)-(meqCl+meqS). Milk composition was determined on Milkoscan equipment, the levels of Ca, P inorganic and Mg in blood serum were determined photometricaly with the use of kits (POCH, Gliwice).…”