Document Type : Original Article
Authors
1
Department of Fisheries, Faculty of Marine Science and Technology, University of Hormozgan, Bandar Abbas, Iran.
2
Department of Fisheries, Faculty of Agriculture and Natural Resources, University of Persian Gulf, Bushehr, Iran.
3
Department of Fisheries, Faculty of Natural Resources, University of Guilan, Sowmeh Sara,, Iran.
4
Department of Fisheries, Islamic Azad Unbiversity, Bandar Abbas Branch, Bandar Abbas, Iran.
Abstract
A 6-week experiment was conducted to investigate the effects of dietary supplementation of red macroalga, Gracilaria pygmaea on proximate analysis, apparent digestibility and digestive enzymes activities of Asian sea bass, Lates calcarifer, with an initial mean weight of 28±5.9 g using a completely random design. The experimental diets were prepared using a fishmeal based positive control diet and a fishmeal-soy protein negative control diet supplemented with 3, 6 and 9% of red macro algae. The results indicated that the special growth rate was significantly higher for the 6% G. pygmea inclusion (P<0.05). At the end of the trial, the crude protein, ash and dry matter of fish carcass were not significantly different between the treatments (P>0.05), except for the fish fed with the 3% inclusion diet that exhibited significantly higher lipid level compared to the others (P<0.05). The results of the apparent digestibility of protein, fat and dry matter did not show significant differences (P>0.05), although these values were slightly improved in 6% inclusion treatment. The pepsin activity was decreased by about 1.46-fold and 1.26-fold in fish fed with the 9% diet when compared with those fed with the 3 and 6%, respectively (P<0.05). Activities of amylase and lipase were significantly lower in 9% treatment compared to 3 and 6% treatments (P<0.05). Present findings show the potential of G. pygmaea powder as a dietary supplement up to 6% inclusion in the diet to improve growth performance, carcass proximate composition, apparent digestibility and most of the digestive enzymes activities of the carnivorous Asian sea bass.
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