THE STUDY OF RIBOFLAVIN REQUIREMENT IN BROILER-CHICKENS

Riboflavin status indices in tissues (brain, liver, heart) and blood p lasma, and performance parameters were studied in male and female broi ler chickens in response to a wide range of dietary supplementation of riboflavin in order to establish the requirement for riboflavin in fa st growing modern broilers. The birds fed riboflavin supplemented diet s were increasing their body weight at at higher rate than those fed t he unsupplemented diet, but this was apparent only during the first st age of growth (days 1 to 21). Supplementation of 2 mg riboflavin per k g was sufficient to support the maximum growth rate. Feed consumption was not affected by different levels of dietary supplementation of rib oflavin. The supplementation of riboflavin in the diet increased (p < 0.001) plasma riboflavin level, but the magnitude of response decrease d with age. The main component in the tissues was FAD, followed by FMN and riboflavin. Overall, the dietary riboflavin supplementation had h ighly significant (p < 0.001) effect on tissue FAD, FMN, and riboflavi n status, but the effect of supplementation was clearly pronounced onl y at days 7 and 14, and thereafter the status of FAD, FMN, and ribofla vin in the tissues did no differ between unsupplemented and supplement ed birds. Neither FAD, FMN, and riboflavin nor GSSG-RED activity corre late with the level of supplementation. Saturation levels of riboflavi n in the blood plasma and tissues, corresponded with dietary riboflavi n levels of supplementation at 1 to 2 mg per kg. Based on the performa nce and biochemical data, the dietary requirement of riboflavin for fa st growing broilers should be set at a level of 5 mg/kg. The currently recommended allowance of 3.6 mg riboflavin per kg of ration is not su fficient for modern breeds of broiler chickens.