The effects of garlic-supplemented diets on antibacterial activity against Streptococcus iniae and on growth in orange-spotted grouper, Epinephelus coioides

• Published in: Aquaculture Vol. 364-365; pp. 33 - 38
• Main Authors: Guo, J.J., Kuo, C.M., Chuang, Y.C., Hong, J.W., Chou, R.L., Chen, T.I.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 05-10-2012; Elsevier Sequoia S.A
• Subjects: agar; Allium sativum; animal growth; Antibacterial activity; antibacterial properties; Antimicrobial agents; Aquaculture; bacteria; Brackish; Cod; Diet; Epinephelus coioides; feed conversion; fish feeding; Garlic; Gram-positive bacteria; Grouper; Growth performance; in vitro studies; Marine; marine environment; minimum inhibitory concentration; mortality; Physical growth; powders; Streptococcus iniae; weight gain; Grouper; Antibacterial activity; Garlic; Streptococcus iniae; Growth performance
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2012.07.023

Garlic (Allium sativum) has had an important dietary and medicinal role for centuries and has long been known to have broad antibacterial properties. Streptococcus iniae occurs naturally in marine and estuarine environments and is one of the major opportunistic pathogenic bacteria in wounded or unhealthy grouper. The purpose of this study was to investigate the in vitro antibacterial activity of garlic and the effect of garlic-supplemented diets on growth performance and resistance against S. iniae in orange-spotted grouper (Epinephelus coioides). The in vitro antibacterial activity of garlic against S. iniae was investigated with the agar well diffusion, minimum inhibitory concentration and minimum bactericidal concentration methods and showed a strong inhibitory effect. Fish were fed diets containing 0, 1.3 and 4% of garlic powder for 14days. The cumulative mortality of the fish fed with the 1.3% garlic diet was significantly (p<0.01) lower than that of those fed with the 4% garlic diet and control diet following a challenge with S. iniae and had significantly (p<0.01) higher percent weight gain and feed efficiency. The results indicate that the inclusion of 1.3% garlic in the diet of orange-spotted grouper enhances feed efficiency, fish growth and resistance to infection by S. iniae.
► Allicin level in garlic was quantified by the HPLC method. ► Garlic has strong antibacterial ability against Streptococcus iniae in vitro. ► Garlic in the diet of grouper is able to improve feed efficiency. ► Garlic enhances gain weight and resistance against S. iniae in the grouper.