Submitted to: The Veterinary Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2010
Publication Date: 4/20/2011
Citation: Reinhardt, T.A., Lippolis, J.D., Mccluskey, B.J., Goff, J.P., Horst, R.L. 2011. Prevalence of Subclinical Hypocalcemia in Dairy Herds. The Veterinary Journal. 188:122-124. Interpretive Summary: Periparturient dairy cows suffer immunosuppression and hypocalcemia. This is a significant economic problem in dairy industry due to increased susceptibility of cows to infectious diseases. An association between immunosuppression and hypocalcemia has been characterized by our research. Furthermore, clinical hypocalcemia (milk fever) is associated with secondary diseases, such as mastitis, retained placenta, displaced abomasums, and ketosis. The objective of this study was to determine the prevalence of subclinical hypocalcemia in the U.S. The data showed that subclinical hypocalcemia is widespread and affect on average 50% of all dairy cows at or near calving. Subclinical hypocalcemia in the postpartum cow is not an emerging disease problem, but rather these data suggest that it has been an unrecognized problem that may contribute to the development of a host of postpartum production diseases, such as mastitis, retained placenta, displaced abomasums, and ketosis. The high prevalence of subclinical hypocalcemia should be viewed as potential health risk to the transition cow.
Technical Abstract: Milk fever is the clinical presentation of severe hypocalcemia. However, both the prevalence of and potential impact of subclinical hypocalcemia on transition cow health are unknown. Cows with subclinical hypocalcemia have few or no clinical signs. Despite this lack of clinical signs these cows may be more susceptible to secondary diseases, such as mastitis, retained placenta, displaced abomasums, and ketosis as has been shown for cows with clinical hypocalcemia. The objective of this study was to determine the prevalence of subclinical hypocalcemia in the U.S. As a part of the USDA’s National Animal Health Monitoring System (NAHMS) Dairy 2002 study, serum samples were collected from 1462 cows within 48 h of parturition. The samples were sorted by lactation number: 1st (n = 454), 2nd (n = 447), 3rd (n = 291), 4th (n = 166), 5th (n = 72), and 6th (n = 32). Subclinical hypocalcemia was defined as serum calcium < 8.0 mg/dl. Subclinical hypocalcemia increases with age and was present in 25%, 41%, 49%, 51%, 54%, and 42% of 1st – 6th lactation cows, respectively. Cows in DCAD programs (39% of the samples) had significantly less subclinical hypocalcemia. Cows with serum calcium’s > 8.0 mg/dl had significantly lower serum NEFAs indicating better energy balance than those with subclinical hypocalcemia. Subclinical hypocalcemia can make cows more susceptible to secondary diseases as clinical hypocalcemia and should be considered as a risk factor in transition cow health.