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Effects of dietary organic acids on growth, nutrient digestibility and gut microflora of red hybrid tilapia, Oreochromis sp., and subsequent survival during a challenge test with Streptococcus agalactiae
Author(s) -
Ng WingKeong,
Koh ChikBoon,
Sudesh Kumar,
SitiZahrah Abdullah
Publication year - 2009
Publication title -
aquaculture research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.646
H-Index - 89
eISSN - 1365-2109
pISSN - 1355-557X
DOI - 10.1111/j.1365-2109.2009.02249.x
Subject(s) - tilapia , oreochromis , biology , streptococcus agalactiae , nutrient , food science , organic acid , zoology , bacteria , streptococcus , biochemistry , fish <actinopterygii> , fishery , ecology , genetics
A 14‐week feeding trial was conducted to determine the effects of dietary organic acids. The experimental diets were added with 0, 1, 2 or 3 g kg −1 of a novel organic acid blend or with 2 g kg −1 of potassium diformate and fed to triplicate groups of red hybrid tilapia ( Oreochromis sp.). Upon completion, tilapia were challenged by immersion with Streptococcus agalactiae . There was no significant difference ( P >0.05) in the growth, feed utilization and nutrient digestibility among treatment groups despite a trend towards improved results with fish fed organic acid‐supplemented diets. Diet pH decreased, causing a reduction in the digesta pH of the stomach and gut. Total bacteria per gram of faeces were significantly ( P <0.05) reduced from 1.81 × 10 8 colony‐forming units (CFU) (control group) up to 0.67 × 10 8 CFU in the fish fed organic acid diets. A similar trend was observed for adherent gut bacteria. Cumulative mortality of fish fed no organic acids was higher compared with fish fed organic acid‐supplemented diets at 16 days post challenge. The data showed that dietary organic acids can exert strong anti‐microbial effects and have the potential to exert beneficial effects on growth, nutrient utilization and disease resistance in tilapia.