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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Ruminant Diseases and Immunology Research » Research » Publications at this Location » Publication #159837
Title: RELATIVE ACIDIFYING ACTIVITY OF ANIONIC SALTS COMMONLY USED TO PREVENT MILK FEVER

Author
item Goff, Jesse
item RUIZ, R - ELI LILLY, MEXICO
item Horst, Ronald

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/20/2003
Publication Date: 5/20/2004
Citation: Goff, J.P., Ruiz, R., Horst, R.L. 2004. Relative acidifying activity of anionic salts commonly used to prevent milk fever. Journal of Dairy Science. 87(5):1245-1255.

Interpretive Summary: Milk fever is a disease affecting 6 to 8% of all U.S. dairy cows each year, which means approximately 700,000 cows are affected each year. This disease has been estimated to cost approximately $300/episode, or $210 million annually, as a result of treatment and production losses. The major clinical symptom seen in cows developing this disorder is their inability to stand and eventual lapse into coma if not treated medically. The cows lose muscle and nerve function because blood calcium concentrations fall below the level required to maintain normal electrical activity of the tissues. All mammals have evolved a very intricate system designed to maintain normal blood calcium. Calcium leaves the body in large amounts when cows begin making milk which is rich in calcium. This calcium must be replaced, either by absorbing more from the diet or by removing calcium from the skeleton. In cows that develop milk fever, this system has broken down. In this paper we describe that milk fever can be prevented by providing high concentrations of anions, such as chloride and sulphate, in the diet of animals around parturition. In addition, we have shown that chloride is a much more effective source of anion relative to sulphate. This information will assist scientists, as well as nutritionists and veterinarians alike, in understanding how dietary manipulations of minerals can influence the incidence of milk fever. The information may assist in developing various strategies for treating milk fever and other metabolic disorders in both human and veterinary medicine.

Technical Abstract: High cation diets can cause milk fever in dairy cows as they induce a metabolic alkalosis reducing the ability of the cow to maintain calcium homeostasis at the onset of lactation. Adding anions to the diet can offset the effect of the high cation forages by inducing a milk metabolic acidosis, restoring the ability to maintain calcium homeostasis. The difference in mEq of dietary cations and anions (DCAD) is most often expressed as (Na+ + K+) ' (Cl- + S--). This equation implies that a mEq of chloride and a mEq of sulfate are equipotent in their ability to alter acid-base balance of the cow. Using blood and urine pH to monitor effects on acid-base balance, experiments were conducted to test the relative acidifying activity of various sulfate and chloride anion sources in non-pregnant, non-lactating Jersey cows. Across all experiments, chloride proved to have about 1.6 times the acidifying activity of sulfate. Calcium and magnesium, ignored by the common DCAD equation, had a small, but significant, alkalinizing effect when accompanying chloride or sulfate. The ranking of the anion sources tested at a dose of 2 Eq/d, from most to least potent urine acidifier, was hydrochloric acid, ammonium chloride, calcium chloride, calcium sulfate, magnesium sulfate, and sulfur. These data should allow more accurate prediction of the response of late gestation cows to dietary cation-anion manipulation.