The present study was conducted to evaluate possible bone changes in cattle due to the ingestion of different levels of fluorine from rock phosphate used as a phophorus supplement. The bone material studied were ribs collected from cattle of three experiments where Tapira rock phosphate was used at different levels and during different periods as a partial or sole source of supplementary phosphorus. In the first experiment feedlot cattle ingested during a 6 month period 63 and 128g/day of Tapira rock phosphate containing 1.3% fluorine. In the second experiment cattle maintained in Brachiaria decumbens pastures during 33 months ingested several levels of Tapira rock phosphate in the mineral mixtures. In the third experiment heifers averaging 14 months of age ingested a mineral supplement with Tapira rock phosphate until the 5th lactation period. Careful examination of the rib samples by histological, morphometric and microradiographic techniques revealed no abnormalities which could be related to fluorine ingestion, neither any differences among tretaments regarding the bone structure. These findings support the conclusion that, as far as bone alterations are concerned, Tapira rock phosphate could be used as a source of phosphorus for cattle under the conditions described in the experiments, a practice which would markedly reduce the cost of phosphorus supplementation.
Fluorine; phosphorus supplementation; rock phosphate; bone alterations; cattle
