Lysine needs of summer-reared male broilers from six to eight weeks of age

摘要: Experimentation was conducted to estimate dietary lysine needed optimize production of summer-reared broilers between 42 56 d age. Male Ross x 308 chicks were placed in floor pens an open-sided house and provided common feeds from placement During the subsequent d, birds received a corn-soybean meal basal diet (18% CP 3,250 kcal/kg ME) established provide limiting essential amino acids favorably balanced near requirement levels with exception lysine. Four 0.10% increments L-lysine isonitrogenously displaced L-glutamic acid analyzed values progressing 0.85 1.25%. Body weight gain mortality not altered as increased; however, feed conversion linearly improved. Chilled carcass yield, amount abdominal fat, recovery skinless boneless breast meats affected. Measurements on nitrogen balance plasma total protein, albumin, glucose, uric taken at 49 concurrent study using sample raised-wire cages identical also failed define requirement. However, aspartic transferase increased maximum approximating 1.05% lysine, whereas free concentration highest level. Overall data supported no less than 0.95% that greater previous minimum 0.85% obtained under similar terms without heat stress. Suppression growth stress appears reduce absolute need for lysine; necessary accommodate depressed intake improve its effectiveness.