Author
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Goff, Jesse |
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Horst, Ronald |
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Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/22/1998 Publication Date: N/A Citation: N/A Interpretive Summary: Milk fever, a disease of extremely low blood calcium concentration, affects up to 7% of all dairy cows in the USA each year. This metabolic disease is caused by diets that are high in potassium and/or sodium which cause the blood and urine of the cow to become alkaline. When the blood is alkaline, the cow loses the ability to regulate blood calcium concentration and can develop milk fever. Unfortunately, removing potassium and sodium from dairy cow rations is difficult. An alternative is to add chloride or sulfate to the diet to acidify the cow's blood and urine which counteracts the effects of high potassium or sodium in the diet. The usual sources of chloride and sulfate are anionic salts. While effective, they impart a salty taste to the diet which often reduces feed consumption by the cow which can lead to reduced milk production and other metabolic disease. We tested hydrochloric acid (HCl) as an alternative to the traditional anionic salts for prevention of milk fever. First, we demonstrated that HCl was a more powerful urinary acidifier than calcium chloride, a traditional anionic salt. HCl was also able to acidify the urine of cows within 24 h after incorporation into the diet. Finally, we demonstrated that by feeding HCl to older Jersey cows at risk of developing milk fever we could dramatically reduce the incidence of milk fever, from 63% of control cows to 11% of HCl-treated cows. Cows fed HCl actually ate more feed than cows fed the control ration. Adding HCl to the diet imparts an acidic flavor to the diet instead of the salty taste imparted by traditional anionic salts which may account for the increased consumption of the diet with HCl. Technical Abstract: High potassium diets induce milk fever by alkalinizing the blood of the cow, which reduces the ability to maintain normal calcium concentration. Addition of anions to the diet induces a metabolic acidosis which counteracts the alkalinizing effect of the high cation diets commonly fed to cows. Currently anions are usually added as anionic salts, such as calcium chloride or magnesium sulfate, and urine pH is often monitored to assess the degree of metabolic acidification resulting from the addition of anions to the diet. An alternative source of anions is hydrochloric acid (HCl). When added to the diet of nonpregnant, nonlactating cows, HCl proved a more effective acidifier of urine than calcium chloride. These studies also demonstrate that it is possible to change the acid base status of cows within 24 h of a dietary change. Adding HCl to the diet of cows caused a significant reduction of urine pH and blood pH within 24 h. Upon withdrawal of HCl from the diet, urine pH returned to baseline levels within 48 h. Inclusion of HCl into the prepartal ration of Jersey cows entering lactation significantly reduced the incidence of milk fever from 63% of control cows to 11% of the HCl-treated cows, and also reduced the degree of hypocalcemia experienced by the cows during the periparturient period. Addition of anionic salts to prepartal rations imparts a salty taste to the ration which reduces palatability and intake of the ration. Addition of HCl imparts an acidic taste to the diet. In this trial, consumption of the ration with HCl was greater than consumption of the control ration. HCl should prove an inexpensive, palatable alternative to anionic salts as a means of controlling milk fever in dairy cows. |
