Blood Biochemical Constituents in Calves following Subclinical Levels of Fluoride Toxicosis

To investigate the effect of dietary fluoride (F) on some blood biochemical constituents, twenty male cross-bred calves (aged 6-8 months) were divided into equal groups and fed for 20 weeks on diets of a concentrate mixture and green maize (50:50 for the first 3 months and 40:60 during the later phase). The four dietary treatments differed only with respect to the F content of the mineral mixture. In treatments 1 and 2, the mineral mixture contained dicalcium phosphate, which was replaced with rock phosphate in treatments 3 and 4. However, treatments 2 and 4 were also supplemented with NaF so as to provide an additional 80 mg F/kg diet. The resultant dietary F levels were 7, 79, 132 and 191 ppm in groups 1 to 4, respectively. Blood serum analysis at biweekly intervals (carried out for 18 weeks) indicated that while serum P content did not change significantly, the serum alkaline phosphatase activity increased (p<0.01) at higher levels of F intake. A decline in serum thyroxine (T4) level upon F addition was observed, which, however, failed to alter significantly the serum triiodothyronine (T3) levels.