While most dairy producers know that a down cow soon after calving is a telltale sign of clinical hypocalcemia, or milk fever, a lack of symptoms doesn’t mean the problem isn’t present. Subclinical hypocalcemia is more common than its clinical counterpart, occurring in nearly 50 percent of second- and greater-lactation cows not on anionic salts.1 And it is much more difficult to identify than its clinical counterpart.
Subclincal hypocalcemia is an under-recognized disease, according to Dr. Brian Miller, Professional Services Veterinarian with Boehringer Ingelheim Vetmedica, Inc. “Hypocalcemia is a gateway or connector disease,” he says. “It is linked to almost every disease we face around the time of calving.”
Low calcium levels in the blood can also increase the risk of injuries due to falling and slipping. Low blood calcium levels also have a blocking effect on immune function and increase the risk of mastitis, retained placenta, metritis and pneumonia.
With or without clinical signs, calcium is essential for all muscle and nerve function in the dairy cow — particularly functions that support skeletal muscle strength and gastrointestinal motility. Problems in either of these areas can trigger a cascade of negative events that ultimately reduce dry-matter intake, increase metabolic diseases and decrease milk yield.2
Clinical hypocalcemia is defined as low blood calcium without obvious signs; animals having it often go unrecognized on a dairy. “Typically, these cows are up and wobbly, may be quivering, are off feed, and have reduced rumen motility,” Dr. Miller says. “Milk losses can be substantial, with clinical milk fever cases resulting in a 14 percent loss of milk production in the subsequent lactation. Animals affected by subclinical hypocalcemia can experience a 2 to 7 percent decrease.”
BOVIKALC: Supplementing calcium when she needs it most
Intravenous (I.V.) calcium is necessary for cows that have become recumbent due to milk fever. To reduce the risk for hypocalcemic relapse, oral calcium is indicated following successful I.V. calcium treatment. Administer one oral supplement once the cow is standing, alert and able to swallow, followed by a second oral supplement about 12 hours later. Intravenous calcium is not recommended for cows that are still standing.
Because most cases of subclinical hypocalcemia go undetected on a dairy, an intentional strategy for oral calcium supplementation is cost-effective due to increased milk yield in supplemented cows. Most second- and greater-lactation cows should be given an oral dose at the time of calving and a second dose about 12 hours later.