COMPARISON OF MATERNAL BLOOD AND FETAL LIVER SELENIUM CONCENTRATIONS IN CATTLE IN CALIFORNIA

Selenium concentration was measured in paired maternal blood samples a nd fetal liver specimens collected at a San Joaquin County, Calif, sla ughterhouse (beef = 19, dairy = 54) and from bovine aborted fetuses su bmitted to the California Veterinary Diagnostic Laboratory System (CVD LS; beef = 20, dairy = 20). Of the slaughterhouse samples and specimen s, dairy maternal blood selenium concentration was significantly (P < 0.001) higher (mean +/- SD; 0.22 +/- 0.056 mu g/ml) than that for beef breeds (0.137 +/- 0.082 mu g/ml). The CVDLS mean maternal blood selen ium concentration for the dairy-breed samples (0.192 +/- 0.028 mu g/ml ) was similar to that for the slaughterhouse dairy-breed samples, but was greater than that for the slaughterhouse beef-breed samples. Slaug hterhouse mean fetal liver selenium content also was higher (P < 0.001 ) for the dairy breeds (0.777 +/- 0.408 mu g/g), compared with the bee f breeds (0.443 +/- 0.038 mu g/g). Mean fetal liver selenium content f or slaughterhouse specimens was higher (P < 0.002) than that for the C VDLS specimens (beef, 0.244 +/- 0.149 mu g/g; dairy, 0.390 +/- 0.165 m u g/g). At the CVDLS, dairy fetal liver content was greater (P < 0.001 ) than that for beef breeds. Mean ratio of fetal liver selenium conten t to maternal blood selenium concentration was 3.53 +/- 1.89 for dairy breeds at the slaughterhouse (liver-to-blood correlation [r] = 0.38), and was 2.11 +/- 1.00 for dairy breeds at the CVDLS (r = 0.31) and 3. 43 +/- 1.50 for beef breeds (r = 0.58). Both slaughterhouse breed rati os were significantly (P < 0.002) greater than the CVDLS dairy-breed r atio. On the basis of these results, breed and source location should be taken into account when interpreting selenium values. Fetal liver s elenium content should only be used as a screening test and combined w ith whole blood selenium concentration from clinically normal herdmate s to evaluate herd selenium status.