The effect of decreasing dietary CP and supplementation of lysine and methionine+cystine on the performance of 270 laying hens Lohmann LSL strain was evaluated in this trial. The birds averaging 26 weeks of age were allotted to a stocking rate of 562 cm²/bird as a completely randomized design with five replicate of six birds. The treatments were as follows: T1 = control diet (CD) with 16.5% CP, 0.80% of lysine (L) and 0.70% of methionine+cystine (MC); T2 = 15.25% CP, 0.73% of L and 0.64% of MC; T3 = 14%CP, 0.66% of L and 0.58% of MC; T4 = 15,25% CP with 0.80% of L and 0.64% of MC; T5 = 14% CP with 0.80% of L and 0.58% of MC; T6 = 15,25% CP with 0.73% of L and 0.70% of MC; T7 = 14% CP with 0.66% of L and 0.70 of MC; T8 = 15,25% CP with 0.80% of L and 0.70% of MC and, T9 = 14% CP with 0.80% of L and 0.70% of MC. The diets contained 2,800 kcal of ME. Diets were suppplemented with amino acids at 15.25 and 14.0% of crude protein to show levels of Lys, MC or L+MC similar to control. The birds were fed 110 g of diet/day and water ad libitum and were submitted at a program of light of 17 hours. The variables were evaluated during four periods of 28 days. The decreasing dietary CP from 16.5 to 14% did not affect bird performance, whereas the lysine supplementation of lower protein diet decreased egg production and egg mass and feed:egg mass ratio and feed:egg dozen ratio in relation to control.
amino acidic addition; ideal protein; amino acid limitant
