The present invention is to a safe, biodegradable trace metal binding system that effectively delivers chromium, cobalt, copper, iron, manganese, molybdenum, selenium and zinc to animals. The method of preparing an animal foodstuff composition involves the steps of: providing transgenic algal cells comprising a nucleotide sequence, the nucleotide sequence being capable of expressing a non-native metal-binding protein in the transgenic algal cells; binding the metalbinding protein with at least one metal so as to produce a metal-bound adduct of the metal-binding protein; and admixing the metal-bound adduct with animal foodstuff. The invention is also to a animal foodstuff composition comprising animal foodstuff and transgenic algal cells expressing a non-native metal-binding protein in the transgenic algal cells, such that the transgenic algal cells contain the metal-binding protein and the metal-binding protein being bound to a metal. Inventors: Sayre; Richard (528 Park Blvd., Worthington, OH 43085); Wagner; Richard (3416 Ashwood Dr., Bloomington, IN 47401) Appl. No.: 765142 Filed: January 18, 2001 Current U.S. Class: 424/442; 424/400; 424/439; 424/93.1; 424/93.2; 424/195.17 Intern'l Class: A23K 001/16.5; A23K 001//17 Field of Search: 424/400,439,442,489,931,932,937,195.17,117 References Cited [Referenced By] U.S. Patent Documents 4992207 Feb., 1991 Darnall et al. 5670191 Sep., 1997 Cummings et al. 5686125 Nov., 1997 Mueller. Foreign Patent Documents 99/60838 Dec., 1999 WO.