Dietary hemp by-products containing low levels of endocannabinoids stimulate growth in juvenile turbot
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2008
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Um ensaio de 77 dias foi realizado de modo a avaliar o impacte de uma fonte proteica e lipídica alternativa no crescimento, eficiência alimentar, digestibilidade e oxidação lipídica (TBARS) de juvenis de rodovalho (Scophthtalmus maximus). Quatro dietas isoproteicas (proteína bruta, 50% MS) e isolipídicas (15% MS) foram formuladas. A dieta que continha farinha de peixe e farinha de óleo foi usada como dieta controlo (FMFO). Em comparação com esta dieta, foram adicionalmente formuladas três; uma com 40% de farinha de peixe substituída por farinha de cânhamo (HCFO), outra em que 44% de óleo de peixe foi substituído por óleo de cânhamo (FMHO) e por último uma dieta em que ambos, farinha e óleo de peixe foram substituídos por 40 e 44% de farinha e óleo de cânhamo, respectivamente (HCHO). As dietas foram administradas a duplicados grupos de juvenis de rodovalho (peso corporal inicial ± 31.7 g), alimentados duas vezes por dia à mão até à aparente saciedade num sistema com controlo de temperatura em regime de recirculação. Após a conclusão do ensaio, os resultados de crescimento foram elevados. Os valores do peso corporal médio e do ganho de peso diário dos peixes alimentados com farinha de cânhamo (HCFO; HCHO) ou óleo de cânhamo (FMHO) foram significativamente (P < 0.05) superiores comparativamente aos valores da dieta controlo (FMFO). Os peixes alimentados com a dieta controlo (FMFO) tiveram taxas de crescimento específica (SGR) significativamente mais baixas do que a dos peixes alimentados com farinha de cânhamo (HCFO; HCHO) ou óleo de cânhamo (FMHO) (os valores rondaram os 0.78 a 1.02% dia-1). Contudo, nenhuma diferença significativa foi encontrada entre dietas (HCFO, HCHO e FMHO). Rodovalhos alimentados com HCHO, FMHO e HCFO apresentaram taxas de conversão alimentar significativamente inferiores relativamente à dieta controlo (FMFO), tendo variado entre 1.1 a 1.6. O índice de gordura na composição corporal dos peixes alimentados com óleo de cânhamo (HCHO, FMHO), foram significativamente inferiores (P < 0.05) (7.9% e 6.1%) relativamente aos verificados nas dietas com óleo de peixe (FMFO, HCFO), 12.4% e 11.4%, respectivamente. O índice de proteína na composição corporal de peixes alimentados com a dieta FMHO apresentaram valores significativamente superiores (P < 0.05) em relação aos valores obtidos com a dieta controlo (FMFO), tendo variado entre 65.1% e 61.5%. Os valores da digestibilidade obtidos neste ensaio apresentaram indicações inconsistentes a respeito da qualidade nutritiva da farinha e óleo de cânhamo. O músculo dos peixes alimentados com farinha de peixe e óleo de cânhamo (FMHO) apresentaram um valor de oxidação mais elevado (0.78; P < 0.01) em relação aos restantes tratamentos. No entanto nenhuma diferença foi observada entre a oxidação muscular dos peixes alimentados à base de cânhamo e os peixes alimentados à base de óleo de peixe. Estes resultados sugerem que o óleo de cânhamo parece ter um efeito benéfico na performance dos juvenis de rodovalho, sendo uma fonte valiosa de lípidos. Para além disso, a farinha de cânhamo pode ser uma interessante fonte de proteína alternativa para esta espécie a este nível da substituição na dieta.
A 77 days feeding trial was conducted to examine the impacts of alternate protein and lipid sources on growth, feed efficiency, digestibility and lipid oxidation (TBARS) of juvenile turbot (Scophthtalmus maximus). Four isoproteic (crude protein, 50% DM) and isolipidic (15% DM) experimental diets were formulated. A fishmeal and fish oil based diet was used as control (FMFO). In comparison to this control formulation, in the other three diets, fishmeal was replaced at a 40% level by hemp cake (HCFO), fish oil was replaced at a 44% level by hemp oil (FMHO) and both fishmeal and fish oil were concomitantly replaced at 40 and 44% levels by hemp cake and hemp oil (HCHO). Diets were fed to duplicate groups of juvenile turbot (initial body weight + 31.7 g), fed by hand twice daily and to visual satiation in a thermoregulated recirculating aquaculture system. At the conclusion of the feeding trial, growth rate of turbot showed to be high. Mean body weight and daily weight gain of turbot fed hemp cake (HCFO; HCHO) or hemp oil (FMHO) were significantly (P < 0.05) higher compared to control diet (FMFO). Specific growth rate (SGR) of fish fed control diet (FMFO) were significantly lower than those found in fish fed diets with hemp cake (HCFO; HCHO) or hemp oil (FMHO) (values ranged from 0.78 to 1.02 % day-1), but no significant differences were found among diets HCFO, HCHO and FMHO. Feed conversion ratios (FCRs) of all diets were significantly lower comparing to control (FMFO), and averaged 1.1 to 1.6. Whole-body fat content of fish fed diets with hemp oil (HCHO, FMHO) were significantly lower (P < 0.05), 7.9% and 6.1%, than those found in fish fed diets with fish oil (FMFO, HCFO), 12.4% and 11.4%, respectively. Whole-body protein contents of fish fed diet FMHO were significantly higher (P < 0.05) than the values found for fish fed control diet (FMFO) and averaged 65.1% and 61.5%. Digestibility values obtained presented inconsistent indication concerning the nutritional quality of hemp cake and hemp oil. Muscle of fish fed diet with fish meal and hemp oil (FMHO) presented the higher value of oxidation (0.78; P < 0,01) in when compared to other dietary treatments. However, no differences were observed between the oxidation of muscle in fish fed diet based on hemp in opposite to fish fed diets with fish oil. These results suggest that hemp oil seems to have a beneficial effect on general performance of juvenile turbot being a valuable source of lipids and also that hemp cake can be an interesting alternative protein source for this specie at this level of substitution in the diet.
A 77 days feeding trial was conducted to examine the impacts of alternate protein and lipid sources on growth, feed efficiency, digestibility and lipid oxidation (TBARS) of juvenile turbot (Scophthtalmus maximus). Four isoproteic (crude protein, 50% DM) and isolipidic (15% DM) experimental diets were formulated. A fishmeal and fish oil based diet was used as control (FMFO). In comparison to this control formulation, in the other three diets, fishmeal was replaced at a 40% level by hemp cake (HCFO), fish oil was replaced at a 44% level by hemp oil (FMHO) and both fishmeal and fish oil were concomitantly replaced at 40 and 44% levels by hemp cake and hemp oil (HCHO). Diets were fed to duplicate groups of juvenile turbot (initial body weight + 31.7 g), fed by hand twice daily and to visual satiation in a thermoregulated recirculating aquaculture system. At the conclusion of the feeding trial, growth rate of turbot showed to be high. Mean body weight and daily weight gain of turbot fed hemp cake (HCFO; HCHO) or hemp oil (FMHO) were significantly (P < 0.05) higher compared to control diet (FMFO). Specific growth rate (SGR) of fish fed control diet (FMFO) were significantly lower than those found in fish fed diets with hemp cake (HCFO; HCHO) or hemp oil (FMHO) (values ranged from 0.78 to 1.02 % day-1), but no significant differences were found among diets HCFO, HCHO and FMHO. Feed conversion ratios (FCRs) of all diets were significantly lower comparing to control (FMFO), and averaged 1.1 to 1.6. Whole-body fat content of fish fed diets with hemp oil (HCHO, FMHO) were significantly lower (P < 0.05), 7.9% and 6.1%, than those found in fish fed diets with fish oil (FMFO, HCFO), 12.4% and 11.4%, respectively. Whole-body protein contents of fish fed diet FMHO were significantly higher (P < 0.05) than the values found for fish fed control diet (FMFO) and averaged 65.1% and 61.5%. Digestibility values obtained presented inconsistent indication concerning the nutritional quality of hemp cake and hemp oil. Muscle of fish fed diet with fish meal and hemp oil (FMHO) presented the higher value of oxidation (0.78; P < 0,01) in when compared to other dietary treatments. However, no differences were observed between the oxidation of muscle in fish fed diet based on hemp in opposite to fish fed diets with fish oil. These results suggest that hemp oil seems to have a beneficial effect on general performance of juvenile turbot being a valuable source of lipids and also that hemp cake can be an interesting alternative protein source for this specie at this level of substitution in the diet.
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Dissertação de Mestrado Engenharia Zootécnica