Reduction of the dietary protein levels and amino acid supplementation of European quails (Coturnix coturnix coturnix)

The effects of feeding nine nutrition plans (NP) on the performance of 576 quails, allotted to a completely randomized design with nine treatments of four replicates of 16 birds, were evaluated in this trial. The following NP were analyzed from 1 to 21 days of age: NP1 = 28% of crude protein (CP), 1.5% lysine (L) and 1.1% methionine + cystine (MC) from 1 to 21 days and 24%CP, 1.3%L and 0.9% MC from 22 to 42 days (control); NP2 = 25.2% CP, 1.23% L and 0.83% MC from 1 to 21 days and of 21.6% CP, 1.0% L and 0.74% MC from 22 to 42 days; NP3 = 22.4% CP, 0.71% MC from 1 to 21 days and 1.2% L and 19.2% CP, 0.64% MC and 0.95% L from 22 to 42 days; NP4 = NP2+L; NP5 = NP3+L; NP6 = NP2+MC; NP7 = NP3+MC; NP8 = NP2+L+MC; and NP9 = NP3+L+MC. The diet supplementation from NP4 to NP9 with L, MC or L+MC aimed to provide values of and MC similar to NP1. Diets (2,900 kcal ME/kg) and water were fed ad libitum in both phases. From 1 to 21 days, decreasing dietary crude protein levels from 28 to 22.4% also reduced intake, body weight, weight gain, but did not affect feed conversion. The dietary supplementation with MC increased bird performance. The recommended level of L (1.5%) in a deficient diet in CP (19.2%) and MC (0.71%) decreased quail growth from 1 to 21 days of age. However, meeting the MC requirements decreased dietary CP levels from 28 to 22.4% and from 24 to 19.2%, respectively, for quails from 1 to 21 and 22 to 42 days of age, independent of the lysine supplementation.