Dietary zinc requirement of juvenile soft-shelled turtles（Pelodiscus sinensis）fed diets with or without phytate

• Main Authors: Sheng-Chia Huang, 黃聖佳
• Other Authors: Chen-Huei Huang
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/16602328361009991985

碩士 === 國立嘉義大學 === 水生生物科學系研究所 === 96 === Two experiment were conducted to quantify the dietary zinc requirement of soft-shelled turtle （Pelodiscus sinensis）using zinc sulfate heptahydrate as the dietary zinc source. Experiment 1：A feeding trial was conducted to evaluate the dietary zinc requirement of juvenile soft-shelled turtles. Juvenile soft-shelled turtles of approximate 4.8 g body weight were fed casein based diets supplemented with 0, 10, 20, 30, 50, 70, 90 mg Zn/kg for 10 weeks. Each diet was fed to 20 juvenile soft-shelled turtles. The control basal diet contains 14 mg Zn/kg. Results indicated that no significant difference (p ≥ 0.05) in weight gain (WG), feed conversion ratio (FCR) and protein efficiency ratio (PER) was observed among the dietary treatments. The zinc contents in liver, serum, bones and carapaces of the turtles fed the control diet was the lowest level of among all groups. zinc concentrations in the liver, serum, bones and carapaces increased when dietary zinc increased. Regression modeling using serum and carapaces zinc contents as the dependent variables indicated that the optimum dietary zinc requirement for juvenile soft-shelled turtles was approximately 47-50 mg Zn /kg. Experimental 2：A feeding trial was conducted to evaluate the dietary zinc requirement of turtles fed diets containing 10g/kg phytic acid. Juvenile soft-shelled turtles of approximate 4.7 g body weight were fed casein based diets supplemented with 0, 25, 50, 75, 100, 125, 150 mg Zn/kg for 8 weeks. Each diet was fed to 20 juvenile soft-shelled turtles. Further, Juvenile soft-shelled turtles fed the control basal diet containing 13 mg Zn/kg developed deficiency signs such as poor growth, eye disease, erosion of skin and extremities. Juvenile soft-shelled turtles fed the control basal diet showed lower weight gain (WG), feed conversion ratio (FCR) and protein efficiency ratio (PER) than those fed diets supplemented with zinc（p ≤ 0.05）. The zinc contents in liver, serum, bones and carapaces of the turtles fed the control diet was the lowest level of among all groups. Zinc concentrations in the liver, serum, bones and carapaces increased when dietary zinc increased. Regression modeling using serum and carapaces zinc contents as the dependent variables indicated that when diets contained 10 g/kg phytuc acid the optimum dietary zinc requirement for juvenile soft-shelled turtles was approximately 151-154 mg /kg. In conclusion, dietary phytic acid reduced the zinc bioavailability.