| To evaluate the allowance of Methionine for laying hens on the based isocaloric(ME,11.26MJ/kg), isonitrogenic(CP,16.5%) and isocaloric(ME,11.09MJ/kg), isonitrogenic(CP,13.5%)on the equal digestible amino acid profile.The study was conducted to provide the optimum adding amount of Met under normal protein and low protein diet for peak laying hens,and reduced the cost.(1) The experiment was conducted to evaluate the allowance of Methionine(Met) for laying hens aged 25-48 week. Seven hundred and twenty Hy-Line brown laying hens aged 24 weeks were randomly divided into 6 groups with 6 replicates containing 20 hens each. The Met content of control group was 0.25%, and Met levels for Met addition groups were 0.31%, 0.35%, 0.39%, 0.43% and 0.47%. The experiment lasted for 24 weeks. The result showed as follows:1) The Increase of Met levels significantly increased egg production and egg mass, and decreased the ratio of feed to egg(P<0.05). The egg production in birds fed 0.35% Met increased 4.93% than those fed control diet(P<0.05). Egg mass reached maximum when Met level amounted to 0.35%, followed by 0.39% and 0.43% Met, which increased by 7.39%, 6.84% and 6.37% in the above 3 groups respectively, compared with control group. The ratio of feed to egg in 0.35% Met level was reduced by10.28%, 9.35%, 8.41% or 7.01%, than that in control gro up, 0.31%, 0.43% or 0.47% Met group(P<0.05). Dietary Met levels did not affect feed intake and egg weight.2) The Increase of Met levels significantly increased e ggshell thickness(P<0.05). Dietary Met levels did not affect Egg shape index, Albument heigh, Yolk color, Haugh unit and egg composition(P>0.05).3)The effect of Met level have no rule on serum total protein(TP) content, serum albumin(ALB), uric acid(UA), methane dicarboxylic aldehyde(MDA), total antioxidant capacity(T-AOC), titala superoxide dismutase(T-SOD) and GHS-PX at the age of twenty-eighth week,thirty-second week and forty-eighth week.4) According to quadratic curve estimation of egg production, egg mass, the ratio of feed to egg and egg weight, the optimal Met allowance for laying hens was 0.360%, 0.370%~0.390% and 0.370%~0.380%, during the age24 to 32 weeks, 33 to 40 weeks and 25 to 48 weeks respectively. Therefore, these overall results suggested that the allowance of Met for laying hens may be recommended at 0.370%~0.380%.(2) The experiment was conducted to evaluate the effect of low-protein diets total sulfur Amino Acid(TSAA) : Lysine(Lys) Ratio and the the optimal TSAA:Lys ratio for laying hens under standard ileal digestible(SID) amino acid(AA) pattern. Five hundred and forty Jing hong laying hens aged 30 weeks were randomly divided into 6 groups with 6 replicates containing 15 hen seach.The experiment lasted for 10 weeks.Treatments consisted of six different diets:a control diet(16.5%CP,TSAA/Lys=91Met=0.373%), five low-CP diets(13.5% CP, TSAA/Lys= 85, 88, 91, 94, 97, Met:0.370%, 0.394%, 0.416%, 0.440%, 0.462%)(the level of Lys was constant, increased the level of methionine). The result showed as follows:1)under the SID AA pattern,the feed intake of control group was signific antly higher than low-CP groups(P<0.05), but had no significant differences on egg production,the ratio of feed to egg,egg weight and egg mass(P>0.05).Increasing the TSAA:Lys ratio, egg production show the rise-fall tendency(P=0.069). The indexes of egg quality and egg composition had no significant differences between each group(P>0.05), but the yolk color of low-CP groups were a little higher than control group(P=0.066).2)According to quadratic curve estimation of egg production, the ratio of feed to egg m ass, the most appropriate of Met were 0.409%, 0.408%and 0.419%.(the optimal TSAA:Lys ratio allowance for laying hens were 90.15,91.61 and 90.31). Under the low protein level, the most appropriate of Met was 0.408%~0.419%, the optimal TSAA:Lys ratio was90.15~91.61.Conclusion, Under the normal protein levels(16.5%)the Met requirements of laying hens is 0.370%~0.380%. Under the low protein level(13.5%)and SID AA model,the SID Met requirement of laying hens is 0.408%~0.419%, total Met requirement is 0.428%, the TSAA and Lys ratio is 90.15~91.61(Lys:0.76%)... |
PDF Full Text Request