Betaine transition metal complexes are formed by: a) reacting a solution including an alkali metal salt of chloroacetic acid with a solution including the transition metal salt to give a solution including a chloroacetate transition metal complex; and b) reacting the solution including the chloroacetate transition metal complex with trimethylamine to give a solution including the betaine transition metal complex. Such betaine transition metal complexes may be used as a feed supplement for animals in the process of preparing such animals for market.