Effect of dietary fluoride on dairy cattle: growth of young heifers.

Thirty 5 to 6-mo-old Holstein heifer calves were divided into three groups and fed a control ration or the control ration with sufficient NaF added to furnish an additional 30 or 50 ppm F based on total dry matter intake. Fluoride content of the hay and grain was 5 and 15 ppm, respectively. The addition of 30 or 50 ppm F had no effect on growth or dry matter intake over the next 70 wk. After 1 yr on experiment, concentrations of F for animals in the control, 30, and 50 ppm F groups were 402, 2509, and 3743 ppm F in vertebral biopsies; .06, .21, and .27 ppm F in serum; and 1, 8, and 13 ppm F in urine. Fluoride ingestion had no influence on various indices of anemia, thyroid function, or on differential white cell counts, nor did it influence ration digestibility. These data suggest that young heifers can be fed up to 50 ppm of a soluble fluoride in their ration with no adverse effect.