Article

Effects of kelp Ecklonia maxima inclusion in formulated feed on the growth, feed utilisation and gut microbiota of South African abalone Haliotis midae

Published in: African Journal of Marine Science
Volume 39, issue 2, 2017, pages: 183–192
DOI: 10.2989/1814232X.2017.1338203
Author(s): A NelDepartment of Ichthyology and Fisheries Science, South Africa, BI PletschkeDepartment of Biochemistry and Microbiology, South Africa, CLW JonesDepartment of Ichthyology and Fisheries Science, South Africa, J KempDepartment of Ichthyology and Fisheries Science, South Africa, G RobinsonDepartment of Ichthyology and Fisheries Science, South Africa, PJ BritzDepartment of Ichthyology and Fisheries Science, South Africa

Abstract

The effect of kelp Ecklonia maxima inclusion in formulated feeds on abalone growth and gut bacterial communities has not been previously investigated in South Africa. An eight-month on-farm growth trial was conducted with sub-adult Haliotis midae (∼43 mm shell length) fed graded levels of kelp in formulated feeds. Kelp inclusion (0.44–3.54% of pellet dry mass) promoted faster growth (65.7–74.5% total mass gain), with better feed and protein conversions (apparent feed conversion ratio [FCR] 1.4–1.8, apparent protein efficiency ratio [PER] 2.3–2.7), as compared with the non-supplemented feed (52.3% total mass gain, FCR 2.1, PER 1.9; p < 0.001). Abalone-gut bacterial DNA was sequenced using 16S rRNA gene pyrosequencing and the sequences were clustered into operational taxonomic units (OTUs) at a 97% similarity level. A supplementary 16S rRNA gene denaturing gradient gel electrophoresis (DGGE) analysis was employed. The dominant OTUs differed in terms of their relative abundances, with an autochthonous Mycoplasma strain being significantly more abundant (p = 0.03) in the gut of abalone fed a kelp-supplemented feed. The DGGE band patterns displayed higher within-group variability for abalone fed the control diet, suggesting that dietary kelp inclusion promotes gut-bacteria homeostasis. This may contribute to better feed utilisation and growth in abalone fed kelp-supplemented feeds.

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