Open AccessEvaluation of dietary yellow loess as an antibiotic replacer on growth, immune responses, serological characteristics and disease resistance in rainbow trout, Oncorhynchus mykiss
Author(s) -
Lee Y. K.,
Katya K.,
Yun H. H.,
Yoon M.Y.,
Park J. K.,
Sung J. S.,
Shin H. S.,
Bai S.C.
Publication year - 2016
Publication title -
aquaculture nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.941
H-Index - 79
eISSN - 1365-2095
pISSN - 1353-5773
DOI - 10.1111/anu.12348
Subject(s) - rainbow trout , oxytetracycline , biology , lysozyme , zoology , antibiotics , food science , fishery , fish <actinopterygii> , microbiology and biotechnology , biochemistry
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 −1 diet ( YL 20 ) and oxytetracycline at 5 g OTC kg −1 diet. Forty‐five fish averaging 39.4 ± 1.6 g (mean ± 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 −1 could be a promising alternative of oxytetracycline in rainbow trout.