Toxicity and growth-promoting potential of spermine when fed to chicks

Previous studies have shown that the feeding of putrescine, a biogenic amine and the precursor of the mammalian polyamines, can promote whole-body growth of chicks. The current study was undertaken to determine the effect of spermine, also a biogenic amine and the most cationic of the polyamines, under similar conditions. In Exp. 1, 120 week-old chicks were fed purified crystalline amino acid-based diets containing 0, .2, .4, .6, .8, or 1.0% spermine for 14 d. Spermine proved highly toxic and growth rates were reduced compared with controls when even .2% was fed. In Exp. 2, chicks were fed 0, .0375, .0750, or .1000% spermine. These concentrations proved less toxic than those used in Exp. 1. Supplemental dietary cysteine was then provided at 0, .3, .6, and .9% together with 0, .025, .050, or .400% spermine (Exp. 3) because depletion of cellular glutathione has been suggested as contributing to spermine's toxicity. Even high levels of cysteine supplementation did not overcome spermine's toxicity. Subsequent dietary provision of L-2-oxothiazolidine-4-carboxylic acid (OTC, Exp. 4), a cysteine prodrug, showed that depletion of cellular glutathione was not likely a cause of spermine toxicosis. A trend toward increased weight gain and feed efficiency was observed when low concentrations of spermine were fed. It was concluded, however, that dietary spermine was more toxic to chicks than was previously seen for putrescine, that any growth-promoting effects of dietary spermine are small, and that supplements of dietary cysteine or OTC are unlikely to increase these effects by overcoming spermine toxicosis.