Effects of dietary methanolic extract of hyssop, Hyssopus officinalis, on growth performance, hepatic antioxidant, humoral and intestinal immunity, and intestinal bacteria of rainbow trout, Oncorhynchus mykiss

• Published in: Frontiers in Marine Science 2022-10, Vol.9
• Main Authors: Yousefi, Morteza, Hoseini, Seyyed Morteza, Abtahi, Behrooz, Vatnikov, Yury Anatolyevich, Kulikov, Evgeny Vladimirovich, Rodionova, Natalya Yurievna
• Format: Article
• Language: English
• Subjects: fish nutrition; hepatic antioxidant capacity; herbal additives; intestinal genes; intestinal health
• ISSN: 2296-7745; 2296-7745
• DOI: 10.3389/fmars.2022.1026651

The aims of the present study were to assess the effects of Hyssop, Hyssopus officinalis , methanolic extract (HE) on growth performance, hepatic oxidative status, humoral and intestinal immunity, and intestinal bacteria of rainbow trout, Oncorhynchus mykiss . Fish were allocated into twelve tanks for four treatments, receiving diets containing 0, 100, 250, and 500 mg/kg HE for eight weeks. The results showed that dietary HE supplementation induced no significant differences in the growth performance, feed efficiency, and hematological parameters (P > 0.05). HE supplementation significantly increased total leukocyte count and the highest count was observed in 250 mg/kg HE treatment (P < 0.001). Fish in 250 and 500 mg/kg HE treatments exhibited significantly lower lymphocyte (P = 0.001) and higher neutrophil (P = 0.002) percentages; the former exhibited a significantly higher monocyte percentage (P = 0.021). Hepatic superoxide dismutase (100 and 250 mg/kg HE; P < 0.001), glutathione peroxidase (100 and 250 mg/kg HE; P = 0.001), glutathione reducatse (all HE treatments; P < 0.001), and reduced glutathione (250 mg/kg HE; P = 0.046) significantly increased, whereas hepatic malondialdehyde levels (250 and 500 mg/kg HE; P = 0.007) significantly decreased in HE-treated fish. Plasma total protein, albumin, globulin, lysozyme, and alternative complement significantly increased in 250 and 500 mg/kg HE treatments and plasma total Ig significantly increased in 250 mg/kg HE treatment. Quantitative real time PCR found no Streptococcus iniae , Lactococcus garvieae , Aeromonas hydrophila , Yersinia ruckeri , and Vibrio anguillarum in the fish intestines in any treatments. Lactobacillus sp. was detected in the fish intestinal samples, but there were no significant differences among the treatments (P = 0.352). Intestinal defensin (P = 0.044) and interleukin-1 beta (P = 0.0.035) expressions were significantly up-regulated in 100 mg/kg HE; intestinal interleukin-10 (P < 0.001) and tumor necrosis factor-alpha (P < 0.001) expressions were significantly up-regulated in 100 and 500 mg/kg HE; whereas, intestinal interleukin-6 expression was significantly (P = 0.009) up-regulated in 250 mg/kg HE treatments. It is concluded that HE is able to stimulate humoral and intestinal immune responses and hepatic antioxidant capacity. HE effective concentration in rainbow trout may be in the range of 100-250 mg/kg.