The Research Of Relative Bioavailability Of Phosphorus In Feed Phosphates

Six parameters, the apparent digestion of phosphorus, serum alkaline phosphatase activity, serum inorganic phosphorus, amount of ash, concentration of phosphorus in ash and bone breaking strength was determined by growth and digestion experiment to calculate the relative bioavailability(RBV) of four feed phosphates with slope ratio method. Compare the apparent and true digestibility with RBV for estimation the RBV of four feed phosphates and the best parameter of assessing bioavailability of feed phosphates.The RBV of monocalcium phosphate(MCP), dicalcium phosphate(DCP),defluorinated tricalcium phosphate(DFP) and mono dicalcium phosphate(MDCP) was determined with slope ratio method. KHzPC, was as a reference standard(RBV= 100%). Five phosphates were added to a low phosphorus basal diet at three levels:0, 0. 7 and 1.4 g per kg feed(total 11 diet) .66 DLY piglets(initial weight: 9.4±0.38kg) were paired by weight, sex, and litter and allotted into 33 group and then distributed into 11 treatments. Each treatment group consisted of three pens of two pigs each. Provide feed and water ad libitum and record body weight and feed consumption on time.Serum samples of 3 pigs of each treament were acquired on 14 and 21 days of the experiment for determination of AKP and serum inorganic phosphorus. Digestion experiment was carried out for ten days to determine apparent and true digestibility of feed phosphates on 23, days with all pigs. 3 pigs in per level in three level of MCP were slaughtered after on d 35 of the experiment and the thighbone, tibia, metatarsal were removed for determination of fat-free dry matter, the concentration of ash in it , concentration of phosphorus in ash and bone breaking strength.The result are as follows:1. The sort of feed phosphates affected RBV. The RBV for these phosphates were: MCP, 91-95%, DCP, 73-80%, MDCP, 87-90%, DFP, 71-74%.2. Bioavailability of feed phosphates were affected by different parameters. Apparent digestion of phosphorus had the highest linearly related to the bone parameters, serum parameters did not show a sufficient correlation to the bone parameters, growth performance was placed in the middle.3.The true digestibility of feed phosphates determined by regression analysis technique and difference technique did not show a significantly different.4.The apparent digestibility for these phosphates were: MCP, 88%, DCP, 70%, MDCP, 83%, DFP, 67%.