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Amino acid requirements of white seabream (Diplodus sargus) larvae: effects on growth and performance
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Resumo(s)
Diplodus sargus is a potential species for aquaculture. Constraints to its production are
a high incidence of skeletal deformities and stagnation of the growth rate in juvenile
stage, possibly caused by dietary imbalances. This thesis is focused on the amino acid
(AA) requirements of Diplodus sargus larvae, on the formulation of diets with AA
supplementation and also identifies larvae skeletal deformities patterns (Chapter 2). D.
sargus AA requirements were estimated using the AA profiles from larval carcass. It
was observed that the AA profiles were relatively constant during larval ontogeny, and
dietary imbalances were identified in rotifers and Artemia (Chapter 3). Tyrosine, lysine,
tryptophan and arginine supplementation was tested by tube feeding and lower gut
absorptions efficiencies were observed for these AA. Also, these AA do not seem to be
limiting D. sargus growth (Chapter 4 and 5). Based on the results from Chapter 3, a
microencapsulated casein diet with a balanced AA profile was formulated and was
compared to an unbalanced AA diet and to a live feed diet (control) (Chapter 6). Results
showed lower ammonia excretion and less skeletal deformities in larvae fed a balanced
diet. Tryptophan supplementation in the diet was tested because of its involvement in
skeleton ossification (Chapter 7). However, a decrease on larval growth and no effect on
skeletal deformities were observed. The effect of tyrosine and phenylalanine
supplementation on D. sargus larvae was tested and a higher survival to a temperature
stress test was observed in larvae fed a tyrosine supplementation (Chapter 8). Larvae
given a phenylalanine supplementation had a decreased incidence on vertebral
compressions. In conclusion, an AA balanced diet reduces skeletal deformities and
improves nitrogen utilization. Skeletal deformities do not seem related to tryptophan
deficiency. Supplementation of phenylalanine and tyrosine lead to a decrease on skeletal
deformities and better resistance to a stress test, respectively. From the AA studied;
tryptophan, lysine, phenylalanine, arginine and tyrosine; none seems to be limiting D.
sargus larval growth
Descrição
Tese dout., Aquacultura, Universidade do Algarve, 2008
Palavras-chave
Teses Aquacultura Sargo Diplodus sargus Aminoácidos Alimentação dos peixes Crescimento