Nutritional requirement of digestible lysine for broiler chickens

The objective of this work was to determine, through a digestibility assay, the nutritional recruitment of true digestible lysine for broiler chickens, in the four growing phases. Four-performance experiments, previously performed, allowed the determination of total lysine requirement of broiler chickens in the periods from I to 21. 15 to 40, 22 to 40 and 42 to 48 days of age. Thirty cecectomized adults Leghorn roosters were used, with an average weight of 2316+/-190 g. and individually caged in atteries with excreta collecting trays and using the precision feeding method. A completely randomized design was used, with five treatments (four with diets and one fasted) and six replications. The basal diets horn the four p owing phases, contained 1.0, 0.825, 0.80 and 0.75% total lysine, were used. Based on the determined digestibility coefficients of 93.3; 93.58: 89.70 and 92.25% and considering the Supplemented L-Lysine HCL as 100 % digestible, the true digestible lysine requirements were: 1.130%; 1.075%; 0,95% and 0,84% for 1-21: 15- 40: 22-40 and 42-48 days of age, respectively. Using the linear regression model, the obtained equations were (%total lysine/Mcal) = 0.4335 - 0,003284X R-2 0.98 and (Y) over cap (% digestible lysine/Mcal) 0.41081 - 0,003213X. R-2 0.96 for total and digestible lysine. respectively, where x was the average birds age in days.