Submitted to: Animal Feed Science And Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 6, 2005
Publication Date: January 20, 2006
Citation: Goff, J.P. 2006. Macromineral physiology and application to the feeding of the dairy cow for prevention of milk fever and other periparturient mineral disorders. Animal Feed Science And Technology. 126(3-4):237-257. Interpretive Summary: Inadequate blood calcium (Ca), phosphorus (P), magnesium (Mg), or potassium (K) concentrations can cause a cow to lose the ability to rise to her feet as these minerals are necessary for nerve and muscle function. Less severe disturbances in blood concentrations of these minerals can cause reduced feed intake, poor rumen and intestine motility, poor productivity, and increased susceptibility to other metabolic and infectious disease. Mechanisms for maintaining blood Ca, P, Mg, and K concentrations perform efficiently most of the time but occasionally these homeostatic mechanisms fail and metabolic diseases such as milk fever occur. This review explains how and why these mechanisms fail, which may allow the veterinarian and nutritionist to develop strategies to avoid these disorders.
Technical Abstract: The periparturient cow undergoes a transition from non-lactating to lactating at calving. The animal is tremendously challenged to maintain calcium homeostasis. Those that fail can develop milk fever, a clinical disorder that is life threatening to the cow and pre-disposes the cow to a variety of other disorders. Less dramatic sub-clinical hypocalcemia can also reduce productivity of cattle by reducing feed intake in early lactation. The cause and prevention of milk fever will be discussed, focusing on the role of diet cation-anion difference and use of low calcium diets. The periparturient period also typically causes minor perturbations in blood potassium and phosphorus concentrations. Occasionally these disturbances are severe enough to be the cause of recumbency and the “downer cow” syndrome. Pathogenesis of these syndromes will be discussed. Low blood magnesium concentrations are observed when animals are fed inadequate amounts of magnesium or some factor is present in the diet, which prevents adequate absorption of magnesium. Severe hypomagnesemia can cause tetany and the downer cow syndrome, but more commonly moderate hypomagnesemia impairs the ability of the cow to maintain calcium homeostasis and hypocalcemia occurs secondary to the hypomagnesemia.