NR 48. Effect of mineral supplement intake with different levels of rock phosphate on growing lambs

Abstract

In order to evaluate the effects of the addition of rock phosphate in mineral supplement, thirty two-monthold lambs were included in a feeding trial during nine months. There were three mineral supplements with 9 % of P, with different levels of rock phosphate (0, 20, and 40 % of P from the rock). Weight gains, P in blood and physical, chemical and histological characteristics were studied in femur and ribs. Results indicated that there were no differences (P>.05) in weight gains (31.1, 26.4 and 31.0 g/hd/day) nor P in the blood (5.0, 4.7 and 5.4 mg/%) for T1, T2 and T3, respectively. However, when P was supplied by rock phosphate, at the level of 40 % in the mineral supplement, there was a reduced phosphorus concentration in the epiphysis from 98.2 mg/mL to 66.4 mg/mL and ash in epiphysis from 42.5 % to 31.7 % (P<.05). The same bone structure showed lower P concentration (P<.05) when compared to the diaphysis (66.4 vs.93 mg/ml) and higher (P<.05) fluorine concentration (1.28 vs. 0.63 mg/mL) resulting in a lower resistance to fractures (390 vs. 641 kgf). Ribs were less sensitive to treatments when compared to the femur.