Performance of Chicks Fed Faba Bean (Vicia Faba) Diets Supplemented With Methionine, Sulfate and Cystine

The performance of broiler chicks fed diets (24.8% protein) containing 90% raw faba beans (Vicia faba L. var. minor) and varying levels of methionine, K2SO4 and cystine was determined. The first experiment was a 4(methionine level) × 3(K2SO level) factorial. Optimal performance was obtained for birds consuming diets containing 0.24% added methionine. The contents of total dietary methionine and sulfur amino acids were 0.46 and 0.78%, respectively. The addition of methionine (0.24%) to the basal diet improved growth rate 368% (P < 0.01) and feed:gain ratio 42% (P < 0.01). K2SO4 additions (0.14 or 0.28%) to the basal diet improved weight gain 3% (P > 0.05) and feed:gain ratio an average of 3.6% (P < 0.05). No significant (P > 0.05) K2SO4 × methionine interactions were observed. The second experimental desig n was 3(methionine level) × 3 (no additions, 0.12% K2SO4, or 0.08% cystine). The addition of suboptimal amounts of methionine to the basal diet greatly improved (P < 0.01) the performance of broilers. The addition of K2SO4 and cystine to diets containing suboptimal levels of methionine improved feed:gain ratio slightly (P < 0.05), but not weight gain (P > 0.05). There was also a significant interaction (P < 0.05) in performance among methionine levels and levels of supplemental cystine. The addition of cystine (0.08%) to the basal diet that contained 0.05% added methionine decreased weight gain by 13%, whereas the addition of cystine to the basal diet that contained either 0.10 or 0.15% added methionine resulted in an average increase in weight gain of 10%. Similarly, cystine addition to the low methionine diet did not affect efficiency of feed utilization, whereas the addition of cystine to the diets containing higher levels of methionine resulted in an 8% improvement in feed:gain ratio. It may be concluded that methionine supplementation of a faba bean diet greatly stimulates performance of chicks, whereas an equivalent addition of sulfur as K2SO4 results in a slight improvement in performance. The addition of cystine either improves or depresses performance depending on relative levels of methionine in the diet.