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SUMMARY: In order to assess the influence of dietary protein and the fluoride ion (F) levels on the rumen fermentation and osteo-skeletal changes, 30 crossbred calves (6-8 months; 104 kg body weight) reared on high, medium, and low levels of dietary protein were exposed to either 0 or 200 mg/kg supplemental F (source: NaF) for a period of 210 days. The rumen liquor studies carried out at the end of experimental feeding showed that the diets did not (p>0.05) influence the rumen fermentation as assessed by the total volatile fatty acids and the TCA-precipitable nitrogen concentration in the rumen liquor, although a significantly lower pH was noted in the F-supplemented animals than in the non-F-supplemented groups. The radiological studies conducted at 90 and 210 days of feeding revealed signs of sub-periosteal new bone formation and cortical thickening in the F-supplemented animals. It is concluded that F in the diet at varied levels of protein nutrition did not have any adverse impact on the rumen fermentation but the radiological findings showed typical signs of fluorosis and the protein levels did not significantly influence the susceptibility to fluorosis.
Keywords: Calves; Dietary fluoride; Dietary protein; Fluoride retention; Rumen fermentation.
INTRODUCTION
Toxic levels of the fluoride ion (F) in drinking water and in many foods cause F intoxication (fluorosis) which is prevalent worldwide and endemic in different parts of India.1-4 Earlier investigations showed that poor nutritional status is known to affect skeletal fluorosis, especially when malnutrition and low protein, calcium, and vitamin C intake are present.5-7 Low nutritional levels of food or protein intake increases the amount of F retained in the body,6-8 and an elevated deposition of F in bone occurs in guinea pigs fed low protein diets.9 Conversely, an ameliorative effect of high protein diets on F retention in rats is accompanied by increased urinary excretion of F.10 Tooth wear has been shown to be beneficially influenced by protein supplementation in industry-fluorosed goats.11 Similar results suggesting a reduction in F deposition in the bones of pigs fed high protein diets as compared to low protein diets have also been reported.12 Various studies, conducted by Chinoy et al. in mice and Wang et al. in rats and rabbits, have indicated the importance of dietary protein on the...