Evaluation of dietary yellow loess as an antibiotic replacer on growth, immune responses, serological characteristics and disease resistance in rainbow trout,Oncorhynchus mykiss

Abstract

A 12 weeks of feeding trial was conducted to evaluate the effects of different levels of dietary yellow loess as an antibiotic (oxytetracycline) replacer in rainbow trout, Oncorhynchus mykiss. Five experimental diets were formulated to contain no antibiotics or yellow loess (control/CON), three graded levels of yellow loess 5 (YL 5 ), 10 (YL 10 ) and 20 g YL kg À1 diet (YL 20 ) and oxytetracycline at 5 g OTC kg À1 diet. Forty-five fish averaging 39.4 AE 1.6 g (mean AE SD) were randomly distributed in to 15 aquaria. Triplicate groups of fish were fed one of the experimental diets at 1.5~1.9% of wet body weight per day. At the end of the feeding trial, average weight gain (WG) and specific growth rate (SGR) from fish fed CON diet were significantly lower than those from fish fed YL 10 , YL 20 or OTC diets (P < 0.05). Lysozyme activity from fish fed YL 20 was detected to be significantly higher than that from fish fed CON diet (P < 0.05). While, superoxide dismutase (SOD) activity from fish fed YL 10 and YL 20 was recorded to be significantly higher than that from fish fed CON diet (P < 0.05). Fourteen days of challenge test with bacteria A. salmonicida showed significantly lower survival rate for CON than those of fish fed other experimental diets. Therefore, these results indicated that dietary yellow loess at 10-20 g kg À1 could be a promising alternative of oxytetracycline in rainbow trout.

Evaluation of different dietary additives based on growth performance, innate immunity and disease resistance in juvenile Amur catfish, Silurus asotus

“…On the other hand, SOD are metalloenzymes that catalyze the dismutation of the superoxide radical (O 2-) into hydrogen peroxide (H 2 O 2 ) and molecular oxygen (O 2 ) (Shao et al 2010), which provides an important defense against oxidative damage. In line with the present study, improved immune responses have been recorded in cultured fish with several feed additives such as the combination of b-glucan and BAISM (Yoo et al 2007), b-glucan (Ai et al 2007), herbal extracts (Chelladurai et al 2014), yellow loess (Lee et al 2015b), Song-gang Ò stone (Lee et al 2015b) and Yucca meal (Njagi et al 2017). …”

“…Moreover, fish fed the YM, BG and CONT diets did not show significant differences in terms of FE and PER. The observations with the SG diet is comparable to the findings by Lee et al (2015b) and Won et al (2017) with Song-gang Ò stone and yellow loess, respectively, in rainbow trout Oncorhynchus mykiss as well as Shahkar et al (2015) with Macsumsuk Ò in Nile tilapia Oreochromis niloticus. Growth and feed efficiency improved in olive flounder Paralichthys olivaceus fed a combination of b-glucan and BAISM-contained diets (Yoo et al 2007).…”

“…Song-gang Ò stone (SG) is a naturally sourced and purified mineral material from the Republic of Korea comprising predominantly of iron oxide (Fe 2 O 3 ), silicon dioxide (SiO 2 ), aluminum oxide (Al 2 O 3 ), potassium oxide (K 2 O), sodium oxide (Na 2 O), and other trace compounds (Lee et al 2015a;Won et al 2017). It is considered as one of the important naturally sourced mineral materials that enhances the health status of fish (Choi et al 2004;Lee et al 2015b;Won et al 2017). Fish farmers in the Republic of Korea use Song-gang stone Ò (SG) at 0.5% as dietary inclusion which gives a positive response in olive flounder aquaculture (Choi et al 2004).…”

“…It is the second freshwater farmed fish species with a production of 4607 tons in the Republic of Korea in 2014(FAO 2016. Several dietary additives have been identified to promote growth and immune responses in the aquaculture industry (Choi et al 2004;Ai et al 2007;Yoo et al 2007;NRC 2011;Güroy et al 2014;Lee et al 2015b;Shahkar et al 2015); however, each dietary additive could produce different levels of responses in individual fish species and contribute differently to feed cost. In this regard, the effects of dietary additives from mineral sources have not yet been investigated in Amur catfish.…”

Dietary eicosapentaenoic acid requirement of juvenile rock bream,Oplegnathus fasciatus

“…(), lysozyme activity in fish has been shown to be modulated by dietary HUFA levels. One of the other antioxidant enzymes, SOD, plays a role in removing reactive oxygen species from the cellular environment by catalysing the dismutation of two superoxide radicals to hydrogen peroxide and oxygen (Fattman, Schaefer, & Oury, ; Lee et al., ; Lin, Shie, & Shiau, ; Shao et al., ). In this study, similar trend with the performance of lysozyme was also observed in SOD activity indicating the improvement of fish immune system by dietary EPA.…”