The effects of dietary fluoride on growth and bone mineralization in broiler chicks

Fluoride has been shown to have varying degrees of beneficial effects on bone mineralization and bone strength, despite its toxic effects on growth and leg disorders. Some studies have demonstrated an increase in bone ash resulting from F supplementation. The purpose of the present study was to determine whether low levels of dietary F would have any beneficial effect on the bone strength and leg disorders of young chicks fed P-deficient diets. Effects on BW and feed efficiency were also observed to monitor for F toxicity. One-day-old straight-run Cobb x Cobb broiler chicks were weighed, randomly allocated to treatment groups, housed in electrically heated wire-floored battery brooders, and provided with water and feed for ad libitum consumption. Phosphorus-deficient diets were formulated to induce P rickets with 2 different P sources. Treatment 1 contained feed grade dicalcium phosphate to simulate a commercial diet. Treatment 2 contained purified dicalcium phosphate to represent a diet with minimal F (approximately 0.46 mg/kg). Treatments 3 and 4 used purified dicalcium phosphate as the P source and contained 10 and 20 mg/kg of F from NaF, respectively. Four more treatments were added for experiment 2. Treatments 5, 6, 7, and 8 used purified dicalcium phosphate as the P source and contained 30, 40, 50, and 60 mg/kg of F from NaF, respectively. The analyzed F values in the diet were lower than the formulated values as a result of an unexplained lower than desired rate of recovery (72%) of an internal standard. Chicks fed purified calcium phosphate grew better in experiment 1 (P < 0.05) and had a lower incidence of P-deficiency rickets in experiment 2 (P < 0.01) than did birds fed feed grade dicalcium phosphate. Percentage of bone ash was increased by increasing the F level in the diets in experiment 1, but not experiment 2. It was concluded that even low levels of F, such as those used in the present study, have the potential to increase bone quality.