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Sulfur and chlorine play a non-acid base role in periparturient calcium homeostasis


Roche, JR and Morton, J and Kolver, ES, Sulfur and chlorine play a non-acid base role in periparturient calcium homeostasis, Journal of Dairy Science, 85 pp. 3444-3453. ISSN 0022-0302 (2002) [Refereed Article]

DOI: doi:10.3168/jds.S0022-0302(02)74432-9


The increased risk of periparturient hypocalcaemia through offering high-K feeds in the precalving period has been reported previously. Two experiments (experiment 1 and 2) investigated the effect of KCl fertilizer on pasture mineral concentration, the dietary cation-anion difference (DCAD), and the subsequent effect of this on periparturient plasma and urine mineral status. Experiment 2 examined the effect of precalving Mg source (MgO, MgSO 4 , and MgCl 2 ) and postcalving Ca supplementation on the concentration of Ca and Mg in plasma and urine. Unexpectedly, pasture DCAD increased (P = 0.06) from 434 to 535 mEq/kg DM in experiment 1 as pasture K concentration decreased from 4.2 to 3.5%, primarily because of a corresponding and greater decrease in pasture Cl concentration (from 1.9 to 1.3%). Plasma Ca or Mg concentrations were not affected by pasture K concentration. A linear decline (P < 0.10) in urine Mg suggested a decline in Mg absorption as pasture K increased. In experiment 2, pasture DCAD decreased (P < 0.05) linearly from 403 to 350 mEq/kg DM as pasture K concentration decreased from 3.8 to 3.3%. However, precalving urine pH was not affected by the declining DCAD. Postcalving plasma Ca concentration was affected by precalving Mg source with MgSO 4 > MgCl 2 > MgO. Differences in acid-base balance do not explain the difference between Mg salts. These results indicate that precalving dietary S and Cl concentration plays an important role in Ca homeostasis, in addition to its role in acid-base balance. Supplementation with Ca postcalving increased plasma Ca concentration for 2 d postcalving. Milk production was not affected.

Item Details

Item Type:Refereed Article
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Animal production
Research Field:Animal nutrition
Objective Division:Animal Production and Animal Primary Products
Objective Group:Livestock raising
Objective Field:Dairy cattle
UTAS Author:Roche, JR (Dr John Roche)
ID Code:40813
Year Published:2002
Web of Science® Times Cited:48
Deposited By:Agricultural Science
Deposited On:2007-10-22
Last Modified:2007-10-22

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