饲料中可消化淀粉对大口黑鲈生长、体组成和非特异性免疫指标的影响

配制6种不同可消化淀粉水平(5.93%、8.71%、11.96%、15.11%、18.16%、21.74%)的等氮和等脂肪的饲料,以试验鱼的生长、饲料效率、体组成、血糖及非特异性免疫和血液学参数作指标,评定大口黑鲈饲料中可消化淀粉的适宜水平。用上述6种饲料饲喂初始体质量(28.36 ± 0.10)g 的大口黑鲈48 d,每饲料设3个重复,每重复35尾鱼。采用表观饱食投喂,每天饲喂2次(8:00和16:00)。结果显示,饲料中可消化淀粉水平为21.74%时,大口黑鲈成活率最低；可消化淀粉水平超过8.71%时,鱼体终末体质量、特定生长率和摄食量均显著下降；但饲料效率和蛋白质效率在可消化淀粉水平为11.96%时达到最高。随着饲料中可消化淀粉水平的升高,饲料的蛋白质消化率差异不显著,但脂肪和淀粉的消化率显著降低；全鱼、肌肉、内脏及肝脏的蛋白质含量均显著降低,而水分含量显著升高,脂肪含量在8.71%组达到最高后又显著降低；肝体比、脏体比、肝糖原及血清谷丙转氨酶和谷草转氨酶的活性均显著升高。饲料中可消化淀粉水平高于11.96%时,试验鱼餐后6至12 h呈现持续的高血糖症状；血清蛋白质含量和血清补体活性在可消化淀粉为8.71%时达到最高；而血清溶菌酶活性和头肾白细胞呼吸爆发活性在11.96%组达到最高。另外,红细胞数和红细胞压积未受到饲料中可消化淀粉水平增高的显著影响,但血红蛋白含量显著降低。综合大口黑鲈的生长、饲料效率、体组成、血糖和非特异性免疫指标得出,大口黑鲈对饲料中可消化淀粉的利用与耐受力有限,饲料中可消化淀粉的适宜水平为8.71% ~ 11.96%。

Effects of dietary digestible starch levels on growth performance, body composition,and non-specific immunological index of largemouth bass (Micropterus salmoides)

Six isonitrogenous and isolipidic diets with increasing digestible starch levels (5.93%, 8.71%, 11.96%, 15.11%, 18.16%, 21.74%) were formulated to determine suitable levels of digestible starch in diets for largemouth bass (Micropterus salmoides), based on growth performance, feed efficiency, body composition, serum glucose and non-specific immunological and hematological parameters. Each diet was randomly assigned to triplicate tanks of 35 fish with an average initial weight of (28.36 ± 0.10) g. Test fish were fed to apparent satiation twice daily (8: 00 and 16: 00) over 48 days. At the end of feeding test, fish fed to a diet with 21.74% dietary digestible starch (DDS) showed the lowest survival rate. Final body weight, specific growth rate and feed intake occurred to a significant declining tendency when DDS levels being higher than 8.71%. Feed efficiency and protein efficiency ratio, however, were significantly highest with fish fed to 11.96% DDS diet. With an increasing DDS level, apparent digestibility coefficients (ADCs) of both dietary lipid and starch were found to be lower, but ADCs of dietary protein showed no significant