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Effects of β‐xylanase and 6‐phytase on digestibility, trace mineral utilisation and growth in juvenile red tilapia, Oreochromis niloticus (Linnaeus, 1758) x O. mossambicus (Peters, 1852), fed declining fishmeal diets
Author(s) -
Wallace J. L.,
Murray F. J.,
Little D. C.
Publication year - 2016
Publication title -
journal of applied ichthyology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.392
H-Index - 62
eISSN - 1439-0426
pISSN - 0175-8659
DOI - 10.1111/jai.13055
Subject(s) - phytase , tilapia , biology , xylanase , oreochromis mossambicus , oreochromis , zoology , feed conversion ratio , juvenile , fish meal , food science , enzyme , fishery , biochemistry , fish <actinopterygii> , ecology , endocrinology , body weight
Summary In response to the global sustainability drive to lower fishmeal ( FM ) inclusion in aquatic feeds, exogenous enzymes can improve nutrient digestibility in monogastric plant‐based diets. A 80‐day experiment was conducted to evaluate the combined effects of xylanase and phytase on digestibility, trace mineral utilisation and growth in juvenile red tilapia, Oreochromis niloticus x O. mossambicus , (48.8 g ± 13.9; μ  ±  STD ) fed declining FM diets. Basal diets were formulated to contain 0, 3 and 5% FM with and without xylanase (0.385 g kg −1 ) and phytase (0.075 g kg −1 ), forming six treatments. Each treatment was randomly assigned to four replicates, 20 fish tank −1 ; mean water temperature 28.98 ± 0.73°C. Although the size of the effects was modest, growth performances (feed intake, FCR , growth rate) decreased with lower FM levels (P < 0.05) but improved with enzyme supplementation. Enzyme supplementation increased P digestibility and trace mineral uptake (P < 0.05), but no effects were seen on protein digestibility and N retention. Nevertheless, tilapia fed the enzyme‐supplemented 3% FM and control 5% FM diets performed comparably (P < 0.05). This potentially justifies a 2% FM reduction for tilapia diets using exogenous xylanase and phytase without significant effects on digestibility, trace mineral utilisation and growth.

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