Effect of dietary fluoride on performances and bone characteristics of broilers and the influence of drying and defatting on bone-breaking strength.

A trial with broiler males, housed in cages, was conducted to determine the effect of (added) dietary fluoride at 0, 200, and 400 mg/kg on performance and bone characteristics and the influence of preconditioning (drying, defatting) on bone-breaking strength. The F administration resulted in a significantly (P less than .05) lower weight gain. Feed conversion, however, was not affected. Tibial ash deposition and ash-percentage increased significantly (P less than .05) at both dietary levels of added F. Broiler males fed supplemented F had a significantly (P less than .05) higher incidence of tibial dyschondroplastic plugs and epiphyseal bone with looser structure, as judged macroscopically. Tibial bone strength was significantly (P less than .05) affected not only by dietary F level, but also by preconditioning, resulting in a significant interaction. Administration of F had a significantly negative or positive effect on breaking strength, depending on whether the measurements were carried out on fresh bones or dried (defatted) bones, respectively. This diverging response of F on breaking strength offers a valid explanation for the contradictory results in the literature, demonstrating at the same time that F supplementation of feed or drinking water should be discontinued as a method to improve bone-breaking strength.