Phosphorus concentration in sheep consuming increasing dietary levels of phosphorus

Abstract

Objective: the aim of this experiment was to evaluate the effect of increasing levels of P intake on the P concentration in biological fluids of Santa Ines lambs. Methods: 18 animals were individually confined in metabolic cages for 35 days. Phosphorus levels in the diet were: 25% lower than the level recommended by the NRC (1985) (T1); the recommended level by the same agency (T2); and 25% higher than the recommended level (T3). The experimental design was randomized blocks following a repeat measure arrangement. Two experimental periods of five weeks were evaluated. Saliva, plasma, rumen liquor, feces and urine samples for P determinations were collected during last three weeks of each period, for four consecutive days. Results: for the lowest amount of P intake (1.87 g/day) corresponding to T1 (p<0.05), showed values of plasma P in average of 5.99 mg/100 ml, 42.91 mg of P/100 ml in saliva, 48.64 mg of P/100 ml in ruminal liquor, 0.19 mg of P/kg PV in urine and 1.27 g/day in feces. Except for urine, all values were lower (p<0.05) than T2 and T3. Conclusion: these values can be considered as adequate to maintain the levels of P in the different fluids, and normal for a satisfactory animal performance, indicating that the NRC (1985) P recommended value could be reduced.