Studies On Digestible Methionine And Lysine Requirement Of Egg-Type Cockerels

In order to determine appropriate methionine and lysine requirement and their optimum balance in rations of fattening egg-type cockerels, the experiments were conducted to study the influence of different methionine and lysine levels on growth performance, nitrogen balance, serum uric acid and biochemical index.1. Studies on digestible methionine requirement of fattening egg-type cockerels Experiment with corn-soybean meal type ration was conducted to study methioninerequirement of fattening egg-type cockerels. Methionine level of basic diet were 0.34% during former period (0~6 week) and 0.28% during latter period (7~10 week). Adding synthetic amino acid to basic diet, dietary methionine levels were 0.35%, 0.40%, 0.45%, 0.50% and 0.50% during former period; 0.28%, 0.32%, 0.36%, 0.40% and 0.44% during latter period. According to the results of growth performance, nitrogen balance and serum UA content during 70 days' feeding experiment, optimum methionine (true digestible methionine) requirement of fattening egg-type cockerels with corn-soybean meal type ration were 0.45% (0.44%) during former period and 0.36% (0.33%) during latter period.2. Studies on digestible methionine and lysine requirement of fattening egg-type cockerelsTo study methionine (Met) and lysine (Lys) requirement and their optimum balance of fattening egg-type cockerels, different levels of Met and Lys were added to corn-soybean meal type ration. The results showed survival rate of all groups were 100%, i.e. levels of Met and Lys had no influence on cockerel health. With reciprocal effect of Met and Lys, daily gain of all groups had no significant difference during the whole period (P>0.05). Met (true digestible Met) and Lys (true digestible Lys) requirement for high daily gain were 0.45%(0.44%), 1.09%(1.00%) respectively, Lys/Met=2.42 in former period; 0.36%(0.33%), 1.01%(0.94%) respectively, Lys/Met=2.81 in latter period. Feed conversion ratio, nitrogen retention ratio and serum UA content of all groups had the same tendency with daily gain. Gross profit of group2 and groupS were high in former and latter period respectively. According to comprehensive analysis on growth performance and economic profit, optimum requirement of dietary Met (true digestible Met) and Lys (true digestible Lys) were 0.40%(0.39%), 1.01%(0.92%) respectively, Lys/Met=2.53 in former period; 0.36%(0.33%), 1.01%(0.94%) respectively, Lys/Met= 2.81 in latter period. Combining the above optimum levels of Met and Lys during the whole period, fattening results of egg-type cockerels were best.