The role of dietary calcium concentration in the use of anionic salts to prevent parturient paresis in dairy cows.
The role of dietary calcium concentration during the feeding of anionic salts (AS) was reviewed. Hypocalcaemia is still the major cause of parturient paresis in dairy cows. Feeding AS is an established method for preventing severe hypocalcaemia by activating the calcium metabolism in the last two to three weeks before parturition by inducing a metabolic acidosis. In compensation for this acidosis, the organism increases the concentrations of ionised Ca [Ca2+] in the blood. This increase leads to an increasing excretion of calcium via the urine, which is ensued by an increased calcium absorption in the intestine. The ongoing metabolic acidosis changed the flux of Ca. The size of the Ca pool, however, remained unchanged. As the calcium metabolism is activated by AS, it seems necessary to increase the amount of calcium that is fed to the cows. Several studies examined the impact of different dietary calcium concentrations on the acid-base balance and the calcium metabolism in cows fed anionic salts. The study designs vary concerning the amounts of calcium fed and the use of pregnant or non-pregnant cows. Only one study combined the feeding of AS with a very low amount of calcium, which fell below the daily requirements of pregnant cows in the last three weeks before parturition. In this study, the calcium balance post partum was better in the cows that were administered AS and a high calcium diet. In the other studies, the amount of calcium in the different experimental groups and the difference between the amounts of calcium fed varied greatly. As far as it was monitored in the studies, the calcium concentration of the diet did not have a significant impact on the degree of acidosis induced by AS. In pregnant cows, no significant differences in the calcium concentration in serum or urine occurred before parturition. Some of the researchers found a lower incidence of parturient paresis when cows were fed a combination of AS and a higher amount of calcium, but some other researches did not. Interestingly, the parameters of bone metabolism did not change between experimental groups. According to what is currently known, the feeding of AS to transition cows should not be combined with a dietary calcium concentration that falls below the requirement of cows in this stage of lactation. On the other hand, there is no need to increase the Ca concentration. When AS are used the dietary calcium concentration should be between 9 g and 12 g/kg dry matter. Further research is needed to investigate the role of dietary calcium regarding the use of AS for improving Ca metabolism in dairy cows around parturition.
Gelfert
Carl-Christian
CC
Klinik für Wiederkäuer, Department für Nutztiere und Bestandsbetreuung, Veterinärmedizinische Universität Wien. carl-christian.gelfert@vu-wien.ac.at
Staufenbiel
Rudolf
R
D000136:Acid-Base Equilibrium / Q000187:drug effects; D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000838:Anions / Q000008:administration & dosage* / Q000378:metabolism; D002136:Calcium, Dietary / Q000008:administration & dosage* / Q000378:metabolism; D002417:Cattle; D002418:Cattle Diseases / Q000517:prevention & control*; D003612:Dairying / Q000379:methods; D005260:Female; D006996:Hypocalcemia / Q000378:metabolism / Q000517:prevention & control / Q000662:veterinary*; D010319:Parturient Paresis / Q000378:metabolism / Q000517:prevention & control*; D011247:Pregnancy; D012492:Salts / Q000008:administration & dosage
D000838:Anions; D002136:Calcium, Dietary; D012492:Salts