Digestible Lysine Requirement of Liuzhou Mahua Broilers at Different Growth Stages

Experiments were conducted to determine the digestible lysine (DLys) requirement of Liuzhou Mahua broilers from 1 to 21 d and from 22 to 42 d of age. Monofactorial design was adopted in this study. 1200 one-day-old healthy broiler chicks were divided randomly and evenly into five treatments, and were all fed with isoenergetic diet (with ME of 3.0 Mcal/kg) but with graded levels of DLys: 1.22%, 1.12%, 1.02%, 0.91% and 0.81% during the period of 1 to 21 days; 1.13%, 1.02%, 0.92%, 0.82% and 0.71% during the period of 22 to 42 days. The results showed that the DLys level in diet had a quadratic relationship both with the average daily gain (ADG) and feed:gain ratio (F/G). For Liuzhou Mahua broilers from 1 to 21 d of age, ADG was the highest at the DLys level of 1.12%, which was not significantly different from those at the levels of 1.22% and 1.02% (P>0.05), and F/G was the lowest at the DLys level of 1.22%. For Liuzhou Mahua broilers from 22 to 42 d of age, at the DLys level of 1.02%, ADG was the highest, and F/G was the lowest, but not significantly different from those at the levels of 1.13% and 0.92% (P>0.05). According to regression analysis results, for Liuzhou Mahua broilers from 1 to 21 d of age, the optimum DLys requirement was 1.07% with ADG as the indicator, and was 1.13% with F/G as the indicator. For Liuzhou Mahua broilers from 22 to 42 d of age, with ADG and F/G as the indicator, DLys requirement were 0.89% and 0.84%, respectively. Liuzhou Mahua broilers were not as sensitive to DLys concentration variation as fast-growing broilers from abroad.