Exploring rock phosphate as a calcium and phosphorus source for Wistar rat nutrition

Abstract

Calcium and phosphorus play fundamental roles in skeletal development and metabolic regulation in livestock. Rock Phosphate (RP), is a naturally occurring calcium-phosphorus rich resource, with a high fluoride content which could trigger fluoride toxicity in livestock. Yet the volatility of fluoride at relatively low temperatures may eliminate this threat. Therefore, this study evaluated the bioavailability of calcium and phosphorus from raw rock phosphate, RRP and heat treated rock phosphate, HTRP in rat diets, against a bone meal control. The evaluation was conducted in seven-week-old hypocalcaemic Wistar rats (n=30, weighing 103.00±14.68 g) individually housed in a stainless steel cages for 10 days in a Completely Randomised Design-CRD (10 rats per treatment). The rats were maintained on a cycle of 12-hour light and12-hour dark of 10 days with calcium and phosphorus in a modified AIN93G diet supplied by BM, RRP and HTRP, and deionised water supplied ad libitum. Urine samples were collected for calcium and phosphorus analyses and three rats per treatment were sacrificed for whole carcass calcium/phosphorus analyses, femoral morphometric and physical properties. Data were analysed using descriptive statistics and analysis of variance at α_0.05. Urine calcium and phosphorus levels of rats were not influenced by the diets. Wistar rats fed BM; RRP and HTRP diets on whole carcass dietary calcium were not significantly influenced. However, whole carcass dietary phosphorus of 1.85 mg/g RRP treatment was similar to that 0f 2.0 mg/g control diet. Femoral trabecular spacing of 675.02±114.32 (µm) in rats fed RRP were higher than 560.49±61.04 (µm) in rats fed control diet. Physical femoral Parameters revealed dietary treatments had no significant (P>0.05) impact. In conclusion, calcium and phosphorus from rock phosphate were bioavailable in Wistar rats as evaluated.