Chelated zinc reduces the dietary zinc requirement of channel catfish, Ictalurus punctatus
Tippawan Paripatananont,
Richard T. Lovellfile:///C:\Users\tianyi\AppData\Local\Temp\ksohtml\wps_clip_image-14716.png
Department of Fisheries and Allied Aquacultures, Auburn University, Auburn, AL 36849 USA
Abstract
The dietary zinc requirements of year-1 channel catfish were determined with an egg-white-based purified diet and with a soybean-meal-based practical diet, each supplemented with serial concentrations of zinc methionine (ZnMet) or zinc sulfate heptahydrate (ZnS). In the egg white diet, supplemental dietary zinc requirements, determined by broken-line regression analysis, for ZnMet and ZnS for maximum weight gain were 5.58 and 18.94 mg/kg, respectively, and for maximum bone zinc deposition were 6.58 and 19.91 mg/kg, respectively. In the soybean meal diet, supplemental dietary zinc requirements for ZnMet and ZnS for maximum weight gain were 5.91 and 30.19 mg/kg, respectively, and for maximum bone zinc deposition were 12.82 and ≥ 80 mg/kg, respectively. The relative bioavailabilities of ZnMet, with ZnS as the standard, were 352% for weight gain and 305% for bone zinc deposition in the egg white diet, and 482% for weight gain and 586% for bone zinc deposition in the soybean meal diet. This experiment showed that ZnMet has approximately 3 times the potency of ZnS in a purified diet and 4–5 times the potency of ZnS in a practical diet containing phytic acid for meeting the dietary zinc requirements of channel catfish.
