Adverse effects of low concentrations of dietary RNA addition on the growth, food intake and kidney weight of young chickens.

1. The effects of 0, 10 and 50 g/kg of RNA in diets on the growth and food intake of chicks from 6 to 21 d of age were examined. Their effects on renal tissue were examined by light microscopy at the end of experiment. 2. Total food intake and growth decreased with the increase in dietary RNA content and kidney weight was significantly increased by 50 g/kg RNA addition. A significant increase in liver weight was also observed in chickens fed on the diet-supplemented with 10 g RNA/kg. 3. The enlarged kidney caused by dietary RNA contained many crystals which were composed mainly of calcium salts but did not contain purines. 4. It is concluded that relatively low dietary RNA concentrations decrease food intake and growth and cause enlarged kidneys which contains many crystals composed mainly of calcium salts.