The performance of broiler chicks fed diets containing extruded cottonseedmeal supplemented with lysine

Three experiments were conducted to test the hypothesis that extruding cott onseed meal (CSM) with supplemental lysine improves its feeding value by de toxifying gossypol. The performance of 1-wk-old straight-run Peterson x Arb or Acres broiler chicks fed diets containing 20% feed-grade or extruded CSM was compared with that of control chicks fed corn and soybean meal-based b roiler rations. All diets were formulated to meet minimum NRC requirements. Lysine levels were adjusted by addition of synthetic lysine at rates of 0. 5 to 2.0% of the protein in CSM. In all experiments, weight gain, feed intake, and feed conversion ratio (FC R) of broilers at 21 d were significantly affected by the diets. Feeding fe ed-grade and extruded CSM resulted in decreased body weight gain, increased feed intake, and inefficient feed utilization. When 2% lysine was added to feed-grade or extruded CSM, the body weight gains of chicks were not signi ficantly different from those fed the control diet. The FCR of chicks fed f eed-grade and extruded CSM plus 2% lysine at 21 d was significantly better than that of chicks fed feed-grade or extruded CSM alone. Abdominal fat pad s las a percentage of body weight) were significantly increased by the incl usion of CSM with or without the addition of lysine (P less than or equal t o 0.019). Liver, spleen, and heart weights were not affected by the presenc e of 20% CSM in the diet. The effects of CSM on plasma iron level was not c onsistent. Only in Experiment 1 did CSM cause a significant reduction in pl asma iron. The hemoglobin contents and hematocrit values of blood from chic ks fed diets with 20% CSM were not significantly different from those of th e controls. The extrusion process reduced the free gossypol in CSM, but the total gossypol level was not changed, and chick performance was not improv ed. However, this study shows that, with adequate supplemental lysine, CSM can be used in broiler diets without a reduction in performance.