A New Description of Riboflavin Deficiency Syndrome in Chickens ,

Day-old male broiler chickens were fed for three weeks with diets containing graded levels of riboflavin (0, 0.22, 0.52, 0.88, and 4.53 mg. added per kg. of basal diet). Curled-toe paralysis which is considered indicative of riboflavin deficiency occurred in less than 10% of the birds at the zero levels of added riboflavin while the mortality was about 25%. Commonly, the birds at the lower levels were paralyzed but with their legs spraddled out and without their toes curled downward and inward. The most senstive indicator of riboflavin deficiency was growth rate which was significantly (P < 0.05) reduced at 0.88 mg./kg., a level of added riboflavin which did not cause curled-toe paralysis or death. Another sensitive indicator was altered posture with the head, tail, and wings carried lower than normal. It appears that curled-toe paralysis is a minor aspect of riboflavin deficiency in the modern broiler chicken.