Second lactation and older high-producing cows are prone to suffer blood calcium deficiency. This situation occurs due to the high calcium demands for the quickly growing calf in utero, and colostrum and milk production during the transition period and into early lactation.
Overall, low blood calcium is the single nutrient deficiency with the widest range of negative effects on a cow’s productivity and well-being. Despite U.S. milk production per cow increasing steadily over time, the percentage of cows affected with milk fever has continuously dropped (Table 1). This has been the result of our improved understanding of its pathogenesis. While milk fever affects less than 3% of cows, subclinical hypocalcemia (SCH) is far more common, creating health and pro duction problems at the herd level.
A critical element
Calcium has an active role in muscle, endocrine, and immune functions, and its deficiency can lead to health problems. In a recent study with 796 cows from five different herds, 32 cows had milk fever. Of the remaining 764 cows, 78% incurred SCH (Rodriguez et al.). In other words, when one cow had milk fever, another 24 cows had SCH. The occurrence of displaced aboma sum, ketosis, retained placenta, and metritis was 3.7, 5.5, 3.4, and 4.3 times more likely, respectively, in cows with SCH.
Additional findings during this decade show that SCH remains as a hidden, costly imbalance in dairy cows. Recent research shows cows with SCH had reduced chew ing activity, limited feed intakes, reduced insulin concentration, and a 70% reduction of conceiving at first service.
Continue reading this article published in Hoard’s Dairyman.
