5～8周龄京红蛋鸡饲粮蛋氨酸需要量的研究

Studies on Dietary Methionine Requirement of Jinghong Laying Hens from 5-to 8-week-old

旨在研究中国新培育的京红蛋鸡5~8周龄的蛋氨酸(Met)需要量。选取300只体重相近、健康的29日龄京红蛋鸡,随机分5个处理,饲粮Met水平分别为0.30%、0.37%、0.44%、0.51%和0.58%,每处理5个重复,每重复12只鸡。试验期28d。结果表明:1)饲粮Met水平未显著影响雏鸡平均日增重和采食量(P>0.05),但显著影响体重和料重比(P<0.05),其中0.44%Met组最佳(608.67g和3.13∶1);群体均匀度呈现二次曲线升高,0.37%Met组最佳(91.67%);显著影响胸肌指数、腿肌指数、胸宽和胫长(P<0.05),呈现二次曲线升高,0.44%Met组腿肌指数和胫长发育最好。2)饲粮Met水平显著影响了6周龄末雏鸡胸腺指数、脾脏指数和法氏囊指数(P<0.05);8周龄末饲粮蛋氨酸水平未显著影响雏鸡胸腺指数和法氏囊指数(P>0.05),显著影响了脾脏指数(P<0.05)。其中,0.44%Met组胸腺指数最大,0.37%Met组法氏囊指数达到最大。3)饲粮Met显著影响蛋鸡胰腺、十二指肠指数、空肠指数和空肠长度(P<0.05)。随饲粮Met水平升高,胰腺和肠道指标呈先升后降趋势。4)饲粮Met水平显著影响鸡血清尿酸和碱性磷酸酶水平(P<0.05),其中0.44%Met组碱性磷酸酶水平和尿酸显著高于其他处理组(P<0.05);但饲粮Met水平未见显著影响鸡血清白蛋白、总蛋白、尿素氮水平(P>0.05)。5)通过对体重、料重比、群体均匀度、胸肌、腿肌、胫长和胸宽二次曲线拟合得出总蛋氨酸水平分别为0.43%、0.44%、0.38%、0.45%、0.43%、0.41%和0.40%,平均0.42%。综合鸡群增重、料重比、群体均匀度等经济指标、免疫指标、消化系统发育和血液生化指标,推荐5~8周龄京红蛋鸡饲粮蛋氨酸需要量为0.42%。

The modulation of dietary methionine(Met)levels on Jinghong laying hens from 5-to 8-week-old was studied in this study.Three hundred 29-day-old Jinghong laying hens were randomly allotted to 5dietary treatments,and each treatment contained 5replicates with 5pens per replicate and 12 birds per pen.The methionine levels were 0.30%(0.30% Met),0.37%(0.37%Met),0.44%(0.44% Met),0.51%(0.51% Met)and 0.58%(0.58% Met),respectively.The experiment lasted for 28 days.The result showed that:1)Dietary Met levels had no significant influence on average daily gain and average daily feed intake(P>0.05);feed/gain ratios and bodyweight were significantly affected by dietary Met levels(P<0.05),and the birds in 0.44% Met group were the best(608.67 g and 3.13∶1);community evenness also showed the tendency of a quadratic curve of rising,and the birds in 0.37% Met group were the best(91.67%);the pectorales index,leg muscles index,chest width and shinbone length were significantly affected by dietary Met levels(P<0.05),with a quadratic curve of rising tendency,and the birds in the 0.44%Met group had the best pectorales index and shinbone length.2)By the end of 6th week old,the dietary Met levels had significant influences on the spleen index,thymus index and bursa of fabricius index(P<0.05);By the end of 8th week old,no significant effects were found on thymus index or bursa of fabricius index(P>0.05),but the spleen index was significantly affected(P<0.05),and the birds in 0.44% Met group had the best thymus index with 0.26%,the birds in0.37% Met group had the best bursa of fabricius index.3)Dietary Met levels significantly affected the pancreas,duodenum index,jejunum index and jejunum length(P<0.05).With the increasing of methionine,all the indexes showed the rise-fall tendency.4)Dietary Met levels had significant effect on serum uric acid and alkaline phosphatase levels(P<0.05).The level of uric acid and alkaline phosphatase in the 0.44% Met group was significantly higher than that of the other groups(P<0.05).Dietary Met levels had no significant effects on serum urea nitrogen,albumin,total protein,follicle stimulating hormone,luteinizing hormone and growth hormone(P>0.05).5)According to quadratic curve estimation of the weight,feed/gain,community evenness,chest muscle,leg muscle,chest width and shinbone length,the optimal methionine levels were 0.43%,0.44%,0.38%,0.45%,0.43%,0.41% and 0.40%,which could be averaged to 0.42%.To sum up,the optimal Met requirement for Jinghong laying hens from 5-to 8-week-old is 0.42%.