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Browsing by Author "Cruz Villeda, Diego Alfredo de la"

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  • Effect of dietary essential oils supplementation on growth performance, protein digestibility and digestive enzymes in juvenile gilthead seabream fed a low fishmeal diet
    Publication . Cruz Villeda, Diego Alfredo de la; Dias, Jorge Proença
    A study was undertaken to evaluate the efficacy of supplemental essential oils on the growth performance, protein digestibility and digestive enzyme activities in juvenile gilthead seabream fed a plant protein-rich diet. Four practical diets were formulated to be isonitrogenous (crude protein, 45.4% DM), isolipidic (18.5% DM) and isoenergetic (gross energy 21.4 kJ/g DM). The control diet (CTRL) was formulated with low levels of marine-derived proteins (19%). The same basal formulation was supplemented with a commercial blend of anis, citrus and oregano essential oils at 1.2 g/kg (diet Phyto C), a similar blend but available in an encapsulated form at 0.2 g/kg (diet Phyto E) and this same encapsulated product (0.2 g/kg) together with an autolysed yeast (1 g/kg) made up the third test diet (diet Phyto E+AY). Triplicate groups of 20 gilthead seabream, with a mean initial weight of 27.9  2.1 g were fed one of the four experimental diets during 63 days. At the end of the trial, the specific growth rate of seabream was not significantly affected (P>0.05) by the dietary supplements. Moreover, dietary supplementation had no effect (P>0.05) on the apparent digestibility of protein. However, fish fed the various supplemented feeds showed significantly lower (P<0.05) FCR values than those fed the CTRL diet. Similarly, in comparison to the control treatment, the various supplemental products significantly improved (P<0.05) protein and fat retention. Daily nitrogen gain was not affected (P>0.05) by the dietary treatments, but fish fed diets supplemented with the essential oils showed a significant reduction (P<0.05) of metabolic N losses. Fish fed diet Phyto E+AY showed enhanced activity (P<0.05) of alkaline phosphatase and leucine alanine peptidase. All phytogenic supplements enhanced (P<0.05) digestive pepsin activity, while lipase activity was little affected by the dietary treatments. Supplemental essential oils contributed to a reduction of FCR and an improved retention of protein and fat in seabream juveniles fed a low fishmeal diet.
    2013Master thesis Open access Show more