Suitable condition of enzymatic reactivity for determining the digestibility of feedstuffs phosphorus in vitro by dialysis tube method

Abstract

In order to develop a new method for determining the phosphorus (P) digestibility in vitro in feedstuffs by dialysis tube, a L 32 (4 9 ) orthogonal experiment with eight factors (4 levels for each factor) and a single factor experiment on the enzymatic reactivity were carried out. The sequence of significance of the eight factors on sample-P dialyzability was as follows: trypsin digestion for 6 h, dialyzing solution at 100 mL, pH of pepsin solution at 2.5, pepsin concentration at 2000 U?mL 21 pepsin digestion for 100 min, at temperature of 35uC, trypsin concentration at 1625 U?mL 21 , and pH of trypsin solution at 6.5, respectively. And in vitro dialyzabilities of P in soybean meal, barley, sorghum, peanut meal, and rapeseed meal were (36.91 ¡ 0.58)%, (27.28 ¡ 0.94)%, (26.95 ¡ 0.58)%, (30.51 ¡ 0.83)%, and (20.82 ¡ 1.09)%, respectively.