Improved growth rate in farmed Haliotis midae through probiotic treatment

There is great potential for the use of probiotics in aquaculture to increase growth rates and improve the nutritional status of the cultured animal. In this study, Haliotis midae fed a kelp diet supplemented with Pseudoalteromonas sp. strain C4 exhibited an increased growth rate compared to abalone fed standard kelp feed both under laboratory and farm conditions. The growth rate of antibiotic-treated H. midae was extremely poor in comparison to abalone that had not been treated with antibiotics when fed an unsupplemented kelp diet, reflecting the importance of gastrointestinal microflora in abalone growth. Alginate lyase activity in the H. midae digestive tract was significantly higher in abalone fed kelp supplemented with strain C4 compared to abalone fed unsupplemented kelp. Antibiotic-treated abalone incorporated 14C-labelled strain C4 proteins into their tissue. Although most of the radiolabelled bacterial protein was incorporated into the hepatopancreas, incorporation was also observed in the gills, foot, adductor muscle and intestine. Thus, the Pseudoalteromonas strain tested in this study shows tremendous potential for use as a probiotic in abalone aquaculture, particularly with regard to improving the nutritional status and digestibility of the feed and hence, increasing the growth rate of farmed H. midae.