The influence of dietary protein and energy levels on growth, survival and thyroid hormone (T3 and T4) composition of Lates calcarifer larvae

Journal Publication ResearchOnline@JCU
Nankervis, L.;Southgate, P.C.
Abstract

Two growth trials were conducted to determine the effects of different dietary protein (450–550 g kg−1) and energy contents (18–22 MJ kg−1) on growth, survival and carcass thyroid hormone (T3 and T4) levels of barramundi (Lates calcarifer) larvae. Larvae fed diets containing 21 and 22 MJ kg−1 dietary energy performed consistently better than those fed diets containing 18 and 19 MJ kg−1 dietary energy in terms of final dry weight and total length, while those fed 20 MJ kg−1 had intermediate values for both the parameters. No effects of dietary protein level were discernable from the physical parameters measured; however, larvae fed diets containing the lowest protein and energy combination (450 g kg−1 protein/18 MJ kg−1 energy) had significantly lower carcass T4 levels than larvae in all other treatments, except for those fed the 500 g kg−1 protein/18 MJ kg−1 diet, which had an intermediate value. The results indicate that the optimum diet for L. calcarifer larvae from 14 to 28 days after hatch should contain 500 g kg−1 protein and a minimum of 21 MJ kg−1 dietary energy. Carcass T4 content was influenced by macronutrient inclusion level, and correlated significantly with growth, described by the total length. Reduced T4 levels may indicate a depressed larval status in this species.

Journal

Aquaculture Nutrition

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Volume

12

ISBN/ISSN

1365-2095

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Issue

3

Pages Count

8

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Publisher

Blackwell Publishing

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Publisher Location

Oxford, United Kingdom

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EISSN

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DOI

10.1111/j.1365-2095.2006.00406.x