Effect of feeding Lactobacillus-based probiotics on the gut microflora, growth and survival of postlarvae of Macrobrachium rosenbergii (de Man)

The present study was conducted to study probiotics treatment in the post‐larval diet of Macrobrachium rosenbergii. Three hundred postlarvae (average weight, 114–118 mg±0.11) were divided in five experimental groups each with four replicates. The experiment was conducted for 60 days. Experimental diets were identical in all the aspects except for variation in the probiotics strain. T1 and T2 groups were fed Lactobacillus acidophilus (140×10¹¹ CFU 100 g^?1) and L. sporogenes (24×10⁷ CFU 100 g^?1) respectively. The T3 group was fed L. sporogenes bioencapsulated in Artemia nauplii. T4 was the control group (without probiotic) whereas T5 was fed Artemia along with control diet. The bacteriological study indicated that the gut microflora of postlarvae are devoid of lactic acid bacteria. The probiotic strains were found to have inhibitory effects against the gram‐negative bacterial flora present in the gut. Growth of the probiotic fed groups was significantly higher (P<0.05) than the control group. Significantly higher growth (P<0.05), per cent weight gain (132.5%), specific growth rate (1.41%), feed efficiency ratio (FER) (0.45), protein efficiency ratio (1.29) and protein gain (161.6%) were recorded in T3 group fed Artemia bioencapsulated L. sporogenes over the control group (P<0.05). Although insignificant (P>0.05), growth‐promoting effects of L. sporogenes were found to be higher than L. acidophillus. Survival of the postlarvae was not affected by probiotics in the diet.     

养殖密度对白点鲑幼鱼生长、存活以及行为的影响

研究了养殖密度（3．33、6．93、10．01、13．65kg／m^3）对白点鲑Salvelinus leucomaenis幼鱼生长、存活和行为的影响。经48d的养殖试验,结果表明：养殖密度对白点鲑幼鱼存活率、肥满度影响差异不显著,对其生长离散影响差异显著（P=0．001）;体重变异系数（CV）与养殖密度（SD）呈正相关（CV=0．288SD-5．999,R=0．875,P=0．004）;特定增长率（SGR）随着养殖密度的增加不断减小,二者呈显著负相关（SGR=15．220—5．908SD,R=-0．832,P=0．005）,但净增重随着养殖密度的增加不断增加,且各密度组最终净增重差异极显著（P=0．000）;养殖密度对白点鲑幼鱼的活动行为有一定的影响,低密度鱼集群性较低,对光线、声音等外界刺激反应比较敏感,大部分鱼都在水体底层进食,投饵时易剩料;高密度组的幼鱼相遇频率要高于低密度环境中的频率,彼此相互碰撞与避让,鱼类出现游动急躁情况。