Cows with subclinical milk fever do not show obvious clinical signs, which makes it impractical to identify subclinical cases on farm, says Heather Dann with the William H. Miner Agricultural Research Institute in Chazy, N.Y.

“At Miner Institute we have been measuring blood calcium of fresh cows within 12 hours of calving for several years now, and treat(ing) cows with subclinical hypocalcemia,” Dann says. “However, most herds do not have equipment for real-time calcium analysis, so prevention is the only option for managing subclinical hypocalcemia.”

Dann says that targeting certain fresh cows with oral calcium may be a good preventative move, particularly in herds with a low incidence of milk fever. She points to recent University of Wisconsin research that showed supplementing lame cows and cows with higher milk yield in their previous lactation with oral calcium boluses shortly after calving was beneficial to early-lactation health and milk yield. The research was published in the December 2012 Journal of Dairy Science.