[In vivo digestibility of rice genetically modified with CpTI in WZS mini-pig]

To establish a stable in vivo gastrointestinal model of WZS mini-pig to evaluate the digestibility of rice genetically modified with CpTI (Cowpea Trypsin Inhibitor). METHODS; Three WZS mini-pigs were surgically fitted with O-stomach cannula and T-ileum cannula, and fed with soybean (positive control), CpTI rice and its parental rice meals. The pH value of gastric and intestinal fluid was monitored at different time points. The digested protein products were measured with protein gel electrophoresis at different time points.

The pH value of gastric contents was rapidly neutralized by the meal to approximately 6.0, then the pH was reduced by HCl secretion,and it subsequently was increased after 4-6 hours. Compared with rice,the increase or decrease of pH after soybean being fed was later. Soybean protein segments 13kD,17kD, 34kD and 50kD could be highly detected in gastric and intestinal fluid at 5-6h after soybean being introduced. The segment 13kD was digested in intestine. However, no any protein segment was found in the gastric fluid 0.25h after rice being fed. There was no any difference in digestibility between the rice genetically modified with CpTI and its parental rice.

It is practicable to establish a in vivo model of WZS mini-pig for digestibility. The digestibility of CpTI rice and its parental rice in gastric and intestinal tract in vivo is equivalent.