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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Ruminant Diseases and Immunology Research » Research » Publications at this Location » Publication #153574
Title: PREVALENCE OF SUBCLINICAL HYPOCALCEMIA IN U.S. DAIRY OPERATIONS

Author
item HORST, RONALD
item GOFF, JESSE
item MCCLUSKEY, BRIAN - CEAH, FT. COLLINS, CO

Submitted to: American Dairy Science Association Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 6/23/2003
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Cows developing clinical hypocalcemia are known to experience biochemical and physiologic changes that predispose them to other diseases such as mastitis, retained placenta, displaced abomasums, and ketosis. For example, severe hypocalcemia results in higher plasma cortisol which may exacerbate the immunosuppression ordinarily present at calving; a greater decline in feed intake after calving exacerbating the negative energy balance; decreased secretion of insulin, preventing tissue uptake of glucose, and increasing lipid mobilization. Although milk fever is the clinical manifestation of severe hypocalcemia, an emerging concern is subclinical hypocalcemia. Cows suffering from subclinical hypocalcemia have few overt clinical signs. However, they may be more susceptible to secondary problems than normocalcemic cows. The objective of this study was to determine the occurrence of subclinical hypocalcemia in U.S. dairy operations. As part of the USDA's National Animal Health Monitoring System (NAHMS) Dairy 2002 study, blood samples were taken from 1,446 cows within 48 h of parturition, representing 480 dairy operations in 21 states. Serum was harvested and frozen within 24 h of collection. The samples were divided in 3 groups: 1st lactation (n=442); 2nd lactation (n=424); greater than or equal to 3rd lactation (n=580). Subclinical hypocalcemia was defined as serum calcium less than 8.0 mg/dl. Subclinical hypocalcemia increased with advancing age and represented 25.3%, 43.9% and 57.8% of 1st, 2nd, and greater than or equal to 3rd lactation cows, respectively. Specific management data was also evaluated for association with hypocalcemia. In this study, 38.7% of the animals were identified as being on a DCAD program. Animals on the DCAD program suffered a significantly (P less than 0.01) lower incidence of subclinical hypocalcemia than those not being offered a DCAD program, with the biggest difference observed in the greater than or equal to 3rd lactation group. Animals with calcium values of greater than or equal to 8 mg/dl also had lower serum NEFAs than those that were less than 8 mg/dl, indicating that normocalcemic animals were in better energy status than those suffering from hypocalcemia. Subclinical hypocalcemia can induce some of the same secondary disease problems as clinical milk fever and should be viewed as an impediment to the health of a cow.