Abstract:

In order to understand the nutritive quality and nutrient components in the muscle of seawater cultured
Trachinotus ovatu, the main nutrient components in the muscle and feed of seawater cultured Trachinotus ovatu were
analyzed in this work. Evaluation standards of nutritive quality were based on the Food and Agriculture Organization of the
United Nations/Word Health Organization (FAO/WHO) standard mode. The general nutrient compositions were determined
by routine methods. Amino acid compositions were determined with an amino acid analyzer. Fatty acid compositions were
measured by gas chromatograph-mass spectrometry (GC-MS). The results showed that crude protein and crude fat of fish
feed basically met the nutritional requirements of Trachinotus ovatu. The contents of crude protein, crude fat, crude ash and
moisture in fresh muscle of seawater cultured Trachinotus ovatu were (19.48 ± 0.15)%, (8.40 ± 0.30)%, (1.34 ± 0.06)% and
(70.84 ± 0.06)%, respectively, while crude fat was higher than other fish species. In dry muscle sample, the total content
of amino acids (TAA) was (66.21 ± 1.17)%, and the content of essential amino acids (EAA) was (26.65 ± 0.54)%. Four
delicious amino acids (DAA) accounted for (25.50 ± 0.54)%, the ratio of total essential amino acids to total amino acids
(EAA/TAA) was 40.25%, and the ratio of total essential amino acids to total nonessential amino acids (EAA/NEAA) was
67.36%. It was clear that the content of different amino acids was stable and the proportions of essential amino acids met
FAO/WHO standards. According to nutrition evaluation in terms of amino acids score (AAS) and chemical score (CS), the
first limiting amino acid of both muscle and feed was methionine. In addition, 27 fatty acids were detected in the muscle
of seawater cultured Trachinotus ovatu, with PUFA, EPA and DHA accounting for (32.72 ± 0.05)%, (0.64 ± 0.04)% and
(5.05 ± 0.23)% of the total amount, respectively. The ratios of n-6/n-3 and PUFA/SFA in muscle indicated its food safety
according to the values recommended by the UK Department of Health. Therefore, farmed Trachinotus ovatu is a species
of fish with delicious taste, high content of essential amino acids, balanced nutrient composition, high nutrition value for
human consumption and health benefits. This study showed that the present feed basically meet the requirements for farmed
Trachinotus ovatu growth; however, the quality of farmed Trachinotus ovatus muscle may be improved by increasing the
contents of methionine and n-3 series of fatty acids in the compound feed.

Key words: Trachinotus ovatus, feed, muscle, nutrition, quality evaluation