Dietary effect of Ziziphora clinopodioides extract on zootechnical performance, immune response, and disease resistance against Yersinia ruckeri in Oncorhynchus mykiss

摘要

An eight-week feeding experiment was performed to determine the potential effects of Blue Mint Bush , Ziziphora clinopodioides, extract (ZE) on growth, digestive enzymes activity, immune response (serum and mucus), and disease resistance in rainbow trout. Accordingly, 450 fish (21.19 ± 1.09 g) were divided into five groups and fed with the experimental diets including: ZE 0% (control diet), ZE 0.5 %, ZE 1.5 %, ZE 3% and ZE 4.5 %. The administration of ZE, except ZE 0.5 %, significantly increased weight gain and specific growth rate compared to the control group ( p 0.05). The highest survival rate (56 %) was recorded in the fish fed with ZE 3 % when the fish were exposed to Yersinia ruckeri on 15 days. Collectively, our results demonstrated that ZE-enriched diets, especially at the level of 3 %, supported growth performance, digestive enzyme activity, non-specific immune system, and resistance to Y. ruckeri infection in fry rainbow trout.