Fababeans (Vicia faba L.) were fed to broiler chicks from 1 to 28 days of age in four experiments. In experiment 1, where fababeans were the sole source of supplementary protein, body weights (ranging from 465 to 571 g) and feed-to-grain ratios differed significantly among cultivars (Maris Bead, Strubes, Pavane, Diana, Ackerperle, Fioletowy, and Kleinkoernige) but none of the fababean diets equalled the soybean meal diet. In experiment 2, supplementary protein source (soybean meal and fababean), dietary protein level (18 and 22%), methionine level (0.0 and 0.3, added), and lysine level (0.0 and 0.3, added) significantly affected body weights of chicks. Significant first-order interactions were obtained but in no case were the weights of chicks fed fababean diets equal to those fed soybean meal diets. In experiment 3, where fababeans were used to supply 25% of the 22% protein in the diets, there were no significant differences in chick weights among fababean cultivars or among the cultivars grown under different N treatments. Fababeans supported rapid weight gains (701 g) but did not equal soybean meal diets (761 g). In experiment 4, where isocaloric diets of two energy levels were used, fababeans at 20 or 40% of the diet supported as high body weights as soybean meal diets in the low energy diets. In the high energy diets, 20% fababeans also supported as high body weights as soybean meal but the 40% fababean diets did not. In none of the experiments where the diets contained fababeans was the feed-to-gain equal to that of the diets that contained only soybean meal as the protein supplement.
