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Contextualización. El cangrejo rojo americano, Procambarus clarkii, es una especie invasora cuya presencia está confirmada en la zona central de Colombia. En el sur de Estados Unidos, área de distribución natural, es un importante recurso acuícola; sin embargo, se han documentado altos impactos ambientales en zonas donde ha sido introducido, precisamente por su elevada capacidad de colonización y la consecuente afectación a especies nativas. El creciente registro de su presencia en diferentes sistemas del centro del país, sugiere un acelerado patrón de expansión y supone que, tal como se ha presentado en otros países, podrán ocurrir efectos negativos sobre la estructura general de estos ecosistemas de altiplano de no aplicarse mecanismos que permitan algún nivel de control. Vacío de conocimiento. La posibilidad de controlar su expansión mediante erradicación manual es una alternativa viable, siempre que se valide algún tipo de uso; este debe contemplar un estímulo económico para motivar pobladores que se dediquen a su extracción por pesca. El proceso para obtener harina que sirva como fuente proteica para concentrados en acuicultura es una opción que debe ser valorada. Propósito. Se evaluaron tres porcentajes de inclusión de harina de cangrejo, en reemplazo parcial de harina de pescado, en un concentrado formulado para la etapa de alevinaje en trucha arco iris. Metodología. Ejemplares de P. clarkii fueron capturados en el medio, utilizando trampas con carnada animal. Los cangrejos fueron procesados completos hasta obtener harina. El alimento experimental, se elaboró a partir de la valoración en composición de harina; se aplicaron cuatro tratamientos por triplicado, con tres niveles de inclusión de harina de cangrejo (T1: 2 %, T2: 4 % y T3: 6 %) y un control sin harina. Estos fueron suministrados a alevinos de trucha desde el inicio de la alimentación hasta alcanzar 6cm de longitud total. Se realizaron muestreos de longitud total (cm) y peso (g) cada diez días, durante un periodo de 60 días. Mediante análisis de varianza (ANOVA), fueron comparadas las siguientes variables de los alevines al final del periodo: peso final (Pf, g), ganancias en longitud total (GLT, cm), peso (GP, g), factor de conversión alimenticia (FCA), tasa de crecimiento específico (TCE, %), factor de condición (K) y mortalidad (%). Resultados y conclusiones. Entre los tratamientos y para las variables evaluadas, no se presentaron diferencias estadísticamente significativas entre tratamientos. Se concluye que, hasta la talla trabajada, la inclusión a un nivel del 6 % de harina de cangrejo es factible como reemplazo parcial de harina de pescado. La obtención de la harina a partir de ejemplares completos dificulta el balanceo de las dietas con mayores porcentajes de reemplazo.

The necessity of dietary taurine supplementation for preventing green liver symptom and improving growth performance of red sea bream Pagrus major fed nonfishmeal (non-FM) diets was investigated. Yearling red sea bream (initial body weight, 580 g) were fed for 36 weeks on non-FM diets based on soy protein concentrate (SPC) supplemented with taurine at levels of 0%, 0.5%, 1.0%, 1.5%, and 2.0%. Specific growth rate (SGR) and feed conversion ratio (FCR) of fish fed the taurine-unsupplemented SPC diet were markedly inferior. In these fish, incidence of green liver was markedly higher and was accompanied by a decrease of tissue taurine concentration and an increase of hepatopancreatic bile pigment content. The green liver symptom was mainly caused by an increase of hemolysis since the erythrocytes became osmotically fragile due to taurine deficiency. Physiological abnormality and growth performance (SGR and FCR) were markedly improved by taurine supplementation to the SPC diets. These results indicate that dietary taurine supplementation is necessary for yearling red sea bream fed non-FM diet based on SPC to maintain normal physiological condition and growth performance.

:  This study was performed to evaluate the efficacy of taurine supplementation for preventing green liver syndrome and improving growth performance in red sea bream Pagrus major fed a low‐fishmeal (FM) diet. Yearling red sea bream were fed for 34 weeks on low‐FM diets either supplemented with taurine, or without taurine, and the tissue taurine and bile pigment concentrations were measured. Compared to the fish fed the FM diet, fish fed the low‐FM diet without taurine supplementation resulted in inferior feed performances and higher incidence of green liver related to the morphological transformation of the erythrocytes. In these fish, the hepatopancreatic taurine concentration was significantly lower and hepatopancreatic biliverdin concentration was high compared to the fish fed the FM diet. These parameters were markedly improved by taurine supplementation of the low‐FM diet and were similar in levels to the fish fed the FM diet. These results indicate that green liver appearance and inferior feed performances of red sea bream fed the low‐FM diet without taurine supplementation were caused by dietary taurine deficiency, and indicate the requirement of taurine supplementation to low‐FM diets for red sea bream.

Este trabajo tuvo como objetivo evaluar la respuesta productiva y económica de la suplementación de vacas doble propósito en pastoreo de Angleton (Dichanthium aristatum) con ensilaje de millo (Sorghum vulgare) más urea-melaza-azufre, semilla de algodón y harina de pescado en la estación seca en el Valle del Sinú (Colombia). A tal fin se utilizaron 12 vacas Holstein × Cebú en el primer tercio de lactancia, distribuidas aleatoriamente mediante un diseño experimental de sobre-cambio compuesto en cuadrado latino, constituido por tres tratamientos, tres grupos de animales y tres periodos experimentales, así: T1) ensilaje de millo a voluntad más 0,100 kg urea, 0,250 kg melaza y 0,004 kg flor de azufre; T2) ensilaje de millo más 1,5 kg semilla de algodón; y T3) ensilaje de millo más 0,500 kg harina de pescado. Las medias ajustadas para producción de leche fueron de 5,6 ± 0,7, 6,6 ± 1,4 y 5,6 ± 0,6 kg/vaca por día para T1, T2 y T3, respectivamente. Se presentaron diferencias estadísticas entre T2 vs. T1 y T3 pero no hubo diferencias entre estos últimos tratamientos. El consumo de ensilaje de millo fue de 4,1 ± 0,31, 4,3 ± 0,40 y 3,8 ± 0,29 kg MS/vaca por día para T1, T2 y T3, respectivamente; hubo diferencias entre T2 y T3, pero no entre T1 vs. T2 y T3. Las ganancias de peso corporal durante el período experimental fueron de 4,1, 10,0 y 8,4 kg para T1, T2 y T3 respectivamente; hubo diferencias estadísticas entre T2 y T1 pero no entre T3 vs. T2 y T1. Los tres tratamientos son viables económicamente puesto que mostraron ingresos netos positivos, pero el tratamiento T1 presentó la mejor respuesta económica.   

:  To elucidate the hemolytic suppression roles of taurine and the necessity of dietary taurine supplementation in yellowtail Seriola quinqueradiata fed a diet without fishmeal, juvenile fish with an initial body weight of 250 g were fed for 40 weeks in floating net cages on soybean protein diets supplemented with 0, 3.0, 4.5 and 6.0% taurine. Taurine concentration of the experimental diets were 0.03, 33.9, 52.8 and 71.6 mg/g, respectively. On the 21st week, fish fed the taurine unsupplemented diet had inferior growth and feed performances, higher death, and there were incidences of green liver and hemolytic anemia. In this group, hepatic and plasma taurine concentrations, serum osmolality and osmotic tolerance of erythrocytes (EC50 value) were significantly lower, and plasma hydroperoxide concentration was markedly higher than in the taurine supplemented groups. These conditions markedly improved corresponding with the increase of dietary taurine concentration. These results indicate that taurine plays a role in hemolytic suppression through osmoregulation and biomembrane stabilization in fish. In addition, it is suggested that yellowtail requires dietary taurine as an essential nutrition for maintaining physiological condition normally.

This study was conducted to investigate the effect of dietary supplementation of cottonseed and soybean meal (CS) on growth performance, feed utilization, and gossypol accumulation in juvenile (mean body weight 11 g) Japanese flounder Paralichthys olivaceus. Five isonitrogenous and isocaloric experimental diets (designated CS0, CS10, CS20, CS30, and CS40) containing 0, 10, 20, 30, and 40% CS mixture (1:1 w/w) were formulated. After 9 weeks of feeding trial, fish fed all diets did not show significant differences in growth performances, feed utilization, and whole body compositions. Hemoglobin content gradually decreased (P < 0.05) with increments of CS inclusion levels. There was a positive linear relationship between dietary gossypol and total liver gossypol contents. Free radical scavenging activity in the experimental diets gradually increased with increment of dietary CS inclusion. This finding indicates that the mixture of cottonseed and soybean meal with methionine and lysine supplementation could replace up to 40% of fishmeal protein in diets. However, 20% fishmeal protein replacement by dietary inclusion of cottonseed (9.4%) and soybean (8.7%) meal might be the optimum and safe level for the commercial use of CS in juvenile Japanese flounder.

:  The physiology of yellowtail fed a non‐fishmeal diet was examined, with a specific interest in the role of taurine in disease resistance and cholesterol metabolism. Decrease of disease resistance in fish fed a non‐fishmeal diet was confirmed by mortality due to natural infection with pseudotuberculosis and artificial infection with Lactococcus garvieae. It is suggested that the most important symptoms related to decrease of disease resistance in fish fed a non‐fishmeal diet is anemia. Anemia was improved by supplementation with taurine. Significant elevation of relative expression of HMG‐CoA reductase mRNA in fish fed a non‐fishmeal diet suggests that cholesterol synthesis would be activated and not dysfunctional. Plasma cholesterol of these fish was elevated to the levels of control fish by supplementation of both cholesterol and taurine. These results suggest that hypocholesterolemia observed in fish fed a non‐fishmeal diet compared with a fishmeal diet would be caused by insufficient dietary cholesterol and decrease of endogenous cholesterol due to the lack of dietary taurine.

The supplemental effects of cholyltaurine and soybean lecithin to a defatted soybean meal (SBM)-based fish meal-free diet on the hepatic and intestinal morphology of rainbow trout Oncorhynchus mykiss were investigated. A fish meal-based diet (FM), three fish meal-free diets supplemented either with soybean lecithin (SL), bovine gall powder (BG) or cholyltaurine (C-tau) and an unsupplemented fish meal-free diet (NFM), were given to fish (~11 g) for 10 weeks. The growth was the lowest in fish fed diet NFM, intermediate in fish fed diet SL and the highest in fish fed diet FM, BG and C-tau. Hepatocytes of fish fed diet NFM were atrophied, and the distal intestine of these fish showed abnormal features: disintegrated microvilli and fatty degeneration in epithelial cells and increased amount of connective tissue in the submucosa. Hepatic and intestinal histological features in fish fed diets SL, BG and C-tau were similar to those in fish fed diet FM. These results indicate that soybean lecithin, bovine bile salts and cholyltaurine have similar effects on normalizing the hepatic and intestinal morphologies of rainbow trout fed the SBM-based diet, although growth promotion effect was limited in the soybean lecithin.

A 70-day feeding trial was conducted to evaluate the suitability of recycled food wastes [food industry waste (FIW) and soy sauce waste (SSW)] as protein sources in the diet of Oreochromis niloticus fry. Diets were formulated that contained 0 and 20-22%, respectively, recycled food wastes, namely D1 (0% recycled food waste), D2 (20% FIW), D3 (10% FIW and SSW, respectively), D4 (20% FIW and tryptophan), and D5 (22% SSW). Although feed efficiency, net protein retention, and protein efficiency were not significantly different among fish on the different diets (p0.05), those on D3 had a better growth performance than the controls (D1). Fish fed diet D4 (tryptophan supplement) had a higher final weight gain than those fed D2, in addition to the other growth parameters, but these differences were not significant (p0.05), with the exception of total feed intake. D1 produced fish with higher carcass protein, while fish fed on D3 had the highest lipid content. There was no significant difference between groups in terms of carcass moisture and ash contents. These findings show that the proper combination of recycled food waste is suitable for use in the production of fish feed and may ultimately result in reductions in the level of fishmeal in aquafeeds.

Inclusion of the water-soluble fraction of blue mussels Mytilus galloprovincialis as a feed additive was examined with tiger puffer Takifugu rubripes. The control diet mainly consisted of fish meal, potato starch, and pollack liver oil. Experimental diets were formulated to replace 30% and 40% of the fish meal protein with defatted soybean meal (SBM), and were supplemented with 0-20% mussel extracts. Fish of 18 g initial body weight were fed each diet to satiation, twice daily, 6 days per week for 7 weeks at 20degC. Weight gain and protein efficiency ratio of fish fed the diet containing SBM without the extract were significantly lower than those of the control at the 30% replacement level. Addition of 5% or 10% extract improved the growth and feed utilization to levels comparable to those of the control. At 40% substitution, statistically identical growth and feed performance to the control were obtained for diets supplemented with 10% or 20% extract; however, performance for 5% addition was significantly lower. Thus, the water-soluble fraction of blue mussels would be an effective feeding stimulant in aquaculture feed for tiger puffer that makes it possible to replace 30-40% of fish meal protein with SBM.