Effect of dietary fluorine on growth, blood and bone characteristics of growing-finishing pigs.

Three hundred eighty-four growing-finishing pigs were used in two experiments to determine the effect of dietary fluorine (F) on growth, blood and bone physical characteristics. Fourteen dietary treatments were formulated by supplementing F (as NaF) to a milo-soybean meal basal diet (7 ppm F) to provide levels of 7, 132, 257, 382, 507 and 632 ppm F for Exp. 1, and 7, 25, 43, 61, 79, 97, 115 and 133 ppm F for Exp. 2. Average daily gain (ADG) and average daily feed intake (ADFI) were not affected (P greater than .09) when F was fed at levels between 7 and approximately 132 ppm. Average daily gain and ADFI were reduced (P less than .0001) for pigs consuming diets with F concentrations greater than 132 ppm (Exp. 1). Feed conversion was not affected (P greater than .17) by any level of F fed. Serum F and alkaline phosphatase concentrations increased (P less than .01) with increasing dietary F levels. Serum and bone Ca and P concentrations were not affected (P greater than .13) by dietary F levels (Exp. 1). In Exp. 1 and 2, bone F increased (P less than .0001) and metatarsal stress and modulus of elasticity decreased (P less than .0001) as level of F increased in the diet. Bone thickness decreased quadratically (P less than .02) in Exp. 1 and linearly (P less than .0007) in Exp. 2 with increased dietary F levels. Scanning electron microscopy showed an increase in porosity of bones from pigs fed the higher levels of F. Growing-finishing pigs were able to tolerate approximately 132 ppm F for growth, but all of the F levels (greater than or equal to 7 ppm) fed in these two experiments affected bone integrity.