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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 #67495

Title: ANIONIC SALTS IN ALFALFA-BASED DIETS I: EFFECT ON ACID-BASE, MINERAL, AND ENDOCRINE STATUS OF PERIPARTURIENT COWS

Author
item JOYCE, P - UNIV. OF IDAHO, MOSCOW
item SANCHEZ, W - UNIV. OF IDAHO, MOSCOW
item Goff, Jesse

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/6/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Milk fever is a disease affecting 6 to 8% of all US dairy cows each year. The major clinical symptom seen in these cows is a cow that is unable to stand and eventually lapses into a 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 concentrations. When calcium leaves the body in large amounts, as it does in cows that are making milk which is rich in calcium, it must be replaced; either by absorbing more calcium from the diet or by removing calcium stored within the skeleton. In cows that develop milk fever, this system has broken down. In this experiment, we have been able to demonstrate that feeding cows diets with added chloride and sulfate prevents milk fever (by increasing the ability of the cow to use skeletal calcium stores). Adding chloride and sulfate to the diet also increases production of the hormones necessary for intestinal calcium absorption. These results will allow producers to prevent milk fever by simply limiting the amount of potassium and sodium fed to the cows. This will reduce the incidence of milk fever, which costs up to $20 million to treat each year, safely and inexpensively.

Technical Abstract: Feeding a prepartum diet with a negative dietary cation-anion difference is one method for the prevention of parturient paresis. The mechanism by which anionic salts improve periparturient calcium status is unclear. It appears that anionic diets cause subclinical metabolic acidosis which may enhance the release of calcium from the bone, enhance gut calcium absorption, and increase calcium excretion through the urine. Two studies were initiated to examine the effect of dietary cation-anion difference (DCAD) and forage type on acid-base status, mineral metabolism, and endocrine response of periparturient dairy cows. A preliminary study was first conducted to ensure that a negative DCAD alfalfa-based diet would affect acid-base status and be adequately consumed. After confirming this, 49 non-lactating Holstein cows in their last 3 wk of gestation were fed alfalfa-based diets with either +35 (POSDIF) or -7 (NEGDIF) DCAD expressed as [(Na+K)- (Cl+S)]/100 g diet DM or a control grass hay-based diet with +30 DCAD (CON). From 2 d prepartum to parturition, cows fed NEGDIF had the lowest urine pH and the highest blood ionized calcium and serum total calcium concentrations at parturition.