Dietary inclusion effect of yacon, ginger, and blueberry on growth, body composition, and disease resistance of juvenile black rockfish (Sebastes schlegeli) against Vibrio anguillarum

Abstract

Background: To minimize the use of antibiotics and to obtain a more sustainable fish culture and aquaculture industry, development of alternative natural source of immunostimulant to replace antibiotic in aquafeed is highly needed. Objective: Dietary inclusion effect of yacon (YC), ginger (GG), and blueberry (BB) on growth, body composition, and disease resistance of black rockfish against Vibrio anguillarum was compared to ethoxyquin (EQ). Methods: Four hundred eighty juvenile (an initial weight of 4.2 g) fish were randomly distributed into 12 of 50 L flowthrough tanks (forty fish per tank). Four experimental diets were prepared; the control (Con) diet with 0.01% EQ inclusion, and YC, GG, and BB diets at 1% each additive inclusion. Each additive was included into the experimental diets at the expense of wheat flour. Each diet was assigned to triplicate tanks of fish and hand-fed to satiation twice daily for 8 weeks. At the end of 8-week feeding trial, 20 fish from each tank fish were artificially infected by intraperitoneal injection with 0.1 mL of culture suspension of pathogenic V. anguillarum containing 3.3 × 10 6 cfu/mL respectively. Fish were monitored for the following 8 days after V. anguillarum infection and dead fish were removed every 6 h for the first 4 days and 12 h for the rest of the study. Results: Weight gain, specific growth rate (SGR), and feed efficiency ratio (FER) of fish fed the YC diet was higher than those of fish fed all other diets. However, feed consumption, protein efficiency ratio, and protein retention was not affected by dietary additive. Moisture, crude protein, and crude lipid content of the whole body of fish were affected by dietary additive. Analysis of the Kaplan-Meier survival curves showed that survival of fish fed the YC, BB, and GG diets was higher than the Con diet. Conclusion: Oral administration of YC can improve not only weight gain, SGR, and FER of black rockfish, but lower mortality of rockfish at occurrence of V. anguillarum.

Dietary inclusion effect of various sources of phyto‐additives on growth, feed utilization, body composition, and plasma chemistry of olive flounder (Paralichthys olivaceus), and challenge test against Edwardsiella tarda compared to a commercial probiotic (super lacto®)

“…tarda infection. Lee et al (2020) also found that a diet supplemented with 1% YC achieved higher survival of rockfish than a diet with 0.01% ethoxyquin against V . anguillarum .…”

“…Lee et al (2021) found that the incorporation of various plant‐derived additives in the diet had no effect on the whole body composition of rockfish. Unlike these studies, however, a variety of phyto‐ingredients were found to alter the whole body composition of rockfish (Kim et al, 2016; Kim et al, 2018; Lee et al, 2020; Lee, Yun, et al, 2016).…”

“…Similarly, administration of YC markedly improved the growth performance of rockfish when diets containing various commercial plant-originated feed additives, such as 1% YC, GG, tomato, BB, persimmon, cheonggukjang, and broccoli (Kim et al, 2016) or 1% YC, GG, and BB (Kim et al, 2018), were compared to a diet without any additive or a diet with 0.01% ethoxyquin (commercial antioxidant), respectively. In the 8-week trial, superior weight gain was achieved in rockfish fed diets supplemented with 1% YC, GG, and BB compared to fish fed a diet, including 0.01% ethoxyquin (Lee et al, 2020). Discrepancies in growth performance of fish in this study compared to improved growth performance of rockfish (Kim et al, 2016(Kim et al, , 2018Lee et al, 2021) may be attributed to several factors, including fish species, dose and type of additive, storage conditions, administration periods, and the nutritional and physiological status of experimental fish (Cho & Lee, 2012;Harikrishnan et al, 2011;Kim et al, 2019;Lee et al, 2021).…”

“…YC was also shown to possess prebiotic, anti‐diabetic, antioxidant, and antimicrobial properties (Campos et al, 2012; Ohyama et al, 1990; Ojansivu et al, 2011). Several previous studies (Kim et al, 2016; Kim et al, 2018; Lee et al, 2020; Lee, Kim, et al, 2016) revealed that dietary inclusion of YC enhanced the growth performance and improved their antibacterial activities against E. tarda , Streptococcus iniae , S. parauberis , and Vibrio anguillarum in rockfish ( Sebastes schlegeli ).…”

“…Several previous studies (Kim et al, 2016;Kim et al, 2018;Lee et al, 2020; revealed that dietary inclusion of YC enhanced the growth performance and improved their antibacterial activities against E. tarda, Streptococcus iniae, S. parauberis, and Vibrio anguillarum in rockfish (Sebastes schlegeli).…”