2024-03-29T08:31:05Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1757672019-02-12T01:53:45Zcom_10261_14com_10261_8col_10261_393
Yúfera, Manuel
Izquierdo, Marisol
Santos, André
Pinto, Wilson
Dias, Jorge
Moyano, Francisco Javier
Mata, J. A.
Martínez-Rodríguez, Gonzalo
Conceição, Luis E. C.
2019-02-11T14:55:44Z
2019-02-11T14:55:44Z
2015-05
World Aquaculture (2015)
http://hdl.handle.net/10261/175767
http://dx.doi.org/10.13039/501100000780
This study examines the digestive capacity of gilthead seabream (Sparus aurata) larvae in relation to microdiet production technologies, feeding protocols and larval age to obtain a global picture of digestive function in fish larvae fed on microdiets. Two experiments were performed. The first one determined the effect of different microdiet feeding frequencies on the digestive capacity of fish larvae. For that purpose, enzyme activities of 10 dph larvae fed a microencapsulated diet at three different daily feeding frequencies (2, 4 and 8 daily meals) were monitored every three hours along a daily cycle and compared to a control larvae fed on live preys. The second trial examined the effect of a microbound diet prepared with different binders (gelatin, arabic gum, dextrin and sodium alginate). In this experiment, gilthead seabream larvae were fed on microbound microdiets for 15 days.Trypsin and lipase activity showed rhythmic daily variations when the larvae were fed on rotifers with permanent prey availability and also with the microdiet. The trypsin activity changed with the feeding protocol. The trypsin pattern obtained with 8 meals was similar to that of the control, prolonging the protein digestion some few hours more than with 2 and 4 meals. Lipase activity was much lower in larvae fed microdiets than in the control. As the larvae fed continuously up to the end of the light period it is recommended to supply the microdiet particles as frequent as possible to allow prolonged digestion. Feeding on microdiets with different binders induced some variations in digestive enzymes activities. Trypsin activity was significantly higher in larvae fed the gelatin diet, which was the diet with the highest protein content. However, trypsin activity was not correlated with the dietary protein content and it was very low in the larvae fed any other diet. Chymotrypsin and lipase activities were not significantly different among diets with the different binders, but a lower activity was observed in larvae fed diets with dextrin and gelatin. Amylase activities were also similar with the different diets. Despite being highest in larvae fed arabic gum diet containing the highest carbohydrate level, it was not correlated to the carbohydrate contents of the microdiets.Gene expression of the RNA codifying the digestive enzyme precursors appeared in general poorly affected by the different experimental conditions. This response would indicate the dominance of an endogenous programming independent of the feed type.
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Digestive enzyme activity in gilthead seabream larvae fed on experimental microdiets
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