Preventing Milk Fever and Other Associated Disorders

Dr. Ronald L. Boman
USU Extension Dairy Nutritionist
    At the recent “Western Dairy Management Conference” in Las Vegas we were pleased to hear a presentation about preventing diseases at or near calving from Dr. Jesse Goff of the National Animal Disease Center, Ames, Iowa. Since I agree with what he told us, I will focus on some of the highlights of his presentation.

    Milk fever is associated with the sudden and large demand for calcium at the beginning of lactation. To reduce the likelihood of milk fever we need to reduce the pH of the blood. The best way to do this is to reduce the potassium (K⁺) and sodium (Na⁺) content of the diet 2 to 3 weeks before calving. We do this by selecting forages that are low in K⁺ and by not feeding sodium buffers during this 2 to 3 week pre-calving period.

    Alfalfa grown on land that has been heavily manured or fertilized with potassium will be high in K⁺ content. Corn silage is generally lower in K⁺ content. To be sure about the K⁺ content of forages you need a “wet chemistry” analysis. The chloride ion (Cl^-) from such products as Bi-Clor and SoyClor will offset the K⁺ in forages. To be certain of the balance between the cations K⁺ and Na⁺ with the anion Cl^-, you need to employ a competent nutritional consultant.

    Preventing milk fever and hypocalcemia also significantly reduces the incidence of mastitis by not impairing smooth muscle contraction vital to closure of the teat sphincter after milking. Retained placentas should also be reduced if milk fever and hypocalcemia are prevented by allowing normal uterine contractions necessary for the expulsion of the placenta. A decline in plasma calcium concentration around calving decreases abomasal contractility, which is suspected to lead to atony and abomasal distension and thus an increase in the incidence of displaced abomasums. Thus, preventing milk fever and hypocalcemia should also reduce the occurrence of mastitis, retained placenta, and displaced abomasum.

References:

1.	Goff, J.P. 1999. Physiologic factors to consider in order to prevent periparturient disease in the dairy cow, with special emphasis on milk fever. Proc. Western Dairy Management Conference. Las Vegas, NV, April 8-10.
2.	Goff, J.P., and R.L. Horst. 1997. Effects of the addition of potassium or sodium, but not calcium, to prepartum rations on milk fever in dairy cows. Journal of Dairy Science 80:176-186.