罗非鱼对晶体蛋氨酸、包膜蛋氨酸利用的比较研究

COMPARISON STUDY ON UTILIZING CRYSTALLINE OR COATED METHIONINE BY TILAPIA (OREOCHROMIS NILOTICUS ×O. AUREUS)

为比较罗非鱼对晶体蛋氨酸、包膜蛋氨酸的利用效果,设计了鱼粉含量为9%的鱼粉饲料、鱼粉含量为0%的无鱼粉饲料(以豆粕等蛋白替代鱼粉),在无鱼粉饲料基础上分别添加晶体蛋氨酸、包膜蛋氨酸,使其蛋氨酸含量与鱼粉饲料一致,共4种饲料,饲喂平均体重为(1.22±0.07)g/尾的奥尼罗非鱼(Oreochromis niloticus×O.aureus)8周。结果表明,各组罗非鱼增重率分别为1642.7%、1250.3%、1362.0%、1451.7%,饲料系数分别为1.08、1.45、1.30、1.21;在无鱼粉饲料中添加晶体蛋氨酸、包膜蛋氨酸提高增重率8.9%、16.1%(P<0.05),降低饲料系数10.34%、16.55%(P<0.05);包膜蛋氨酸组较晶体蛋氨酸组具有更高增重率和更低饲料系数(P<0.05)。对摄食后不同时间点肝脏和血浆谷草转氨酶(GOT)、谷丙转氨酶(GPT)活性变化的测定表明,鱼粉饲料组、无鱼粉饲料组肝脏GOT、GPT活性分别在摄食后第2、第4h出现高峰;晶体蛋氨酸组在摄食后1h出现高峰,较无鱼粉组提前;包膜蛋氨酸组在摄食后第5h出现高峰,较无鱼粉组滞后;血浆GOT、GPT活性变化趋势与肝脏的基本一致。消化率试验表明,鱼粉饲料组干物质、粗蛋白质消化率最高,无鱼粉饲料组最低;在无鱼粉饲料中添加晶体蛋氨酸、包膜蛋氨酸后,干物质、粗蛋白质消化率均得到显著提高(P<0.05)。上述结果表明,在蛋氨酸缺乏的实用饲料中补充晶体或包膜蛋氨酸,均可显著提高罗非鱼生长性能和营养物质消化率,包膜蛋氨酸较晶体蛋氨酸具有更高的利用效率和更好的促生长效果。

The present study was conducted to compare the ability of utilizing crystalline and coated methionine（Met） in diet of tilapia（Oreochromis niloticus × O.aureus）.Four diets with iso-lipid and iso-nitrogen were designed as fish meal diet（FMD,9% fish meal）,non-fish meal diet（NFMD,0% fish meal）,crystalline Met diet（Cr-Met） and coated Met diet（Co-Met） with crystalline Met or coated Met addition in NFMD to obtain the same Met level as FMD.Tilapia with initial body weight of（1.22 ± 0.07） g was fed the four diets for 8 weeks.The results showed that weight gain（WG） of the four groups were 1642.7%,1250.3%,1362.0% and 1451.7%,feed conversion rate（FCR） were 1.08,1.45,1.30 and 1.21,respectively.Compared with NFMD group,WG increased by 8.9% and 16.1%（P0.05）,and FCR decreased by 10.34% and 16.55%（P0.05） by the addition of crystalline or coated Met in diet.Liver glutamic-pyruvic transaminase（GPT）,glutamic-oxaloacetic transaminase（GOT） activity peak appeared at 2h and 4h after ingesting for fish in FMD and NFMD groups,which was advanced to 1h after ingesting for Cr-Met group,and delayed to 5h after ingesting for Co-Met group.The Plasma GOT,GPT activity had a similar variation trend to that of liver’s.The digestive trial showed that fish of fed FMD had the highest,and which of fed NFMD had the lowest digestibilities of dry matter（DM） and crude protein（CP）.Compared with NFMD group,DM and CP digestibilities were significantly improved by the addition of crystalline Met and coated Met in diet.These results showed that the growth and nutrients digestibility of tilapia could be improved by adding crystalline Met and coated Met in practical diet deficient in Met.Tilapia can utilize coated Met more efficiently than crystalline Met.