Studies on fluorosis of sheep. III. The toxicity of water-borne fluoride for the grazing sheep throughout its life

Abstract

Three experimental groups of lambs were given water containing the same three different levels of fluorine, added as sodium fluoride, that their mothers had received during pregnancy and lactation. Group A (control), containing 21 wethers and 11 ewes, received water containing about 0 . 3 p.p.m. F, group B (17 wethers) received water containing 10 p.p.m. F, and group C (20 wethers and 10 ewes) received water containing 20 p.p.m.F. The ewes were mated in each of the last 6 years, and the experiment was terminated when the animals reached 7 years of age. During the winter months little water was drunk. In the summer months the daily intake of water by groups B and C rose to 41, equivalent to 40 and 80 mg F, for the two groups respectively. Their overall mean daily intake for the whole experiment was 14 and 27 mg F respectively. Water containing 10 p.p.m. F appeared to have no adverse effects on the health of the sheep, but decreased wool production and induced characteristic changes in the teeth. Water containing 20 p.p.m. F affected health and wool production, and induced more severe signs of fluorosis on the teeth. Neither concentration affected reproductive performance. Increases up to threefold were observed in the fluoride content of the bones and teeth. The implications of the findings are discussed, particularly in relation to flock management in Queensland.