Effects of Reducing Dietary Cation-Anion Balance on Calcium Kinetics in Sheep

Abstract

A Ca kinetic study with a four-compartment model being fitted to radioisotope and balance data using the CONSAM (conversational, simulation, analysis, and modeling) computer program was conducted to examine the effects of dietary cation-anion balance, calculated as milliequivalents [(Na + K] - (Cl + S)]. Twelve crossbred wethers were used as eucalcemic control (period 1); then Ca loss during lactation was simulated by continuous infusion of ethylene glycol tetraacetate (period 2). Dietary cation-anion balance was manipulated by supplementation of various mineral salts and was +339, +35, and -127 meq of kg DM-1 during period 1 and +429, +68, and -147 meq of kg DM-1 during period 2 for control and two treatments, respectively. Animals responded to the simulated lactational Ca loss (period 2) by increasing true intestinal absorption of Ca and bone resorption and by reducing Ca accretion by bone. No difference was observed in concentration of total Ca in plasma, but treatments produced increased concentration of plasma ionized Ca during both periods. Both treatments produced hypercalciuria during both periods, and the lowest cation-anion balance increased true intestinal absorption of Ca and reduced bone accretion during period 2. The size of total exchangeable Ca pool did not differ between treatments or periods, but amount of Ca movement between the pools increased with the intermediate cation-anion balance during period 1 and with both treatments during period 2 compared with control. These results indicated that feeding reduced cation-anion balance diets increased Ca flux through the exchangeable Ca pool with no changes in the size of the pool, particularly when Ca demand was increased.

Effect of Dietary Cation-Anion Difference during Prepartum and Postpartum Periods on Performance, Blood and Urine Minerals Status of Holstein Dairy Cow

“…In pre-calving, increased urinary S by decreasing the level of DCAD might be attributed to dietary concentrations. So, more S intake may result in more plasma and urinary concentrations and vice versa (Takagi and Block, 1991). Increased urinary Ca excretion in cows fed −100 DCAD might be due to a slight metabolic acidosis, induced by negative DCAD diet.…”

Effects of prepartum dietary cation-anion difference on aspects of peripartum mineral and energy metabolism and performance of multiparous Holstein cows

“…Previously identified mechanisms for prevention of hypocalcemia with decreasing prepartum DCAD include increased Ca flux prepartum by increasing urinary Ca excretion (Fredeen et al, 1988;Grünberg et al, 2011) and restoring sensitivity of tissues to parathyroid hormone (PTH) stimulation, which is impaired during alkalotic states (Goff et al, 2014). These mechanisms may result in greater bone resorption or increased efficiency of intestinal Ca absorption (Fredeen et al, 1988;Takagi and Block, 1991;Goff and Horst, 1997) or both around parturition. Feeding a negative prepartum DCAD has been demonstrated to increase blood Ca concentrations (Moore et al, 2000;Weich et al, 2013) and improve production outcomes (DeGroot et al, 2010;Weich et al, 2013).…”

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

“…High plasma Ca level may also be attributed to increased Ca absorption from the alimentary tract (Lomba et al, 1978) and Ca mobilization from bones (Bushinsky et al, 1993) due to mild metabolic acidosis, induced by feeding low DCAD diet. Feeding a low DCAD increased the flow of Ca through the readily exchangeable Ca pool (Takagi and Block, 1988) and enhanced the concentration of ionized Ca in the blood (Oetzel et al, 1988).…”

“…In the periparturient period from advanced pregnancy to early lactation, the clearance of Ca to the placenta ceases, but the lactational Ca demand increases rapidly (Ramberg et al, 1984). The reduction of body fluids pH by addition of low dietary cation-anion difference (DCAD) diet can help in Ca mobilization (Takagi and Block, 1988;Bushinsky et al, 1993;Schonewille et al, 1994). The direct implementation of the findings obtained from the studies executed on exotic dairy cows to the indigenous breed that differs in physiological aspects and thrive on dry fodder dominated feeding system would not be a scientific approach.…”