Diversification of dietary protein and lipid sources for the development of fish production: The great challenge for its growth

The aquaculture industry is currently the fastest-growing food production sector in the world, with an average growth rate of 8.8% in the last 50 years. Currently, the production of farmed fish that contributes approximately 50% of the fish consumed globally, constituting 16.7% of the animal protein available. This percentage will grow in the coming years as a result of two factors: the stagnation of catches from the natural environment and the increase in per capita consumption of products of marine origin worldwide. Based on the current trend of exploitation of marine resources, some researchers have predicted a collapse of the species that are currently being fished around the year 2050. This is why aquaculture is increasing significantly, thanks to the intensification of the systems of production and the evolution of manufactured diets. This decrease and collapse of the main fisheries worldwide in recent decades has resulted in the supply of fish oil and meal, which are seriously threatened, so its use in aquaculture is increasingly restricted. The lower availability of these inputs has meant that the price has increased considerably in the last decade. To this must be added the increase in demand for human consumption, fish from the catches, and the greater social pressures that question the fishing destined to fishmeal and fish oils for animal feed instead of being destined for direct human consumption, as well as the high demand for highly unsaturated fatty acids that only the aquatic environment provides, mainly through fish oil

Effect of EPA/DHA ratios on the growth and survival of Galaxias maculatus (Jenyns, 1842) larvae reared under different salinity regimes

Despite the importance of certain highly unsaturated fatty acids in osmotic regulation, few studies have been addressed to determine the essential fatty acid requirements for a given species cultured under different salinities. As Galaxias maculatus is a diadromic species, the present study aimed to determine the effect of salinity on the optimum dietary EPA/docosahexaenoic (DHA) ratio for survival and growth during the larval stages. Larvae were fed for 20 days with rotifers containing two different EPA/DHA ratios (low: 0.64 and high: 2.18) at three different salinities (0, 10 and 15 g L-1). The results of this study showed a marked effect of water salinity on larval dietary lipid utilization in G. maculatus larvae. These results suggested that G. maculatus larvae reared at higher salinities may have a higher dietary requirement for DHA, whereas larvae reared at 0‰ showed higher requirements for EPA. The overall results of the present study indicate that even small changes in salinity can determine the optimum dietary EPA/DHA ratio and the quantitative essential fatty requirements of fish. This may have important repercussions and affect the rearing performance of G. maculatus cultured under different salinities. © 2010 The Authors. Journal Compilation © 2010 Blackwell Publishing Ltd

Incorporation of whole lupin, Lupinus albus, seed meal in commercial extruded diets for Rainbow Trout, Oncorhynchus mykiss: Effect on growth performance, nutrient digestibility, and muscle fatty acid composition

Whole lupin seed meal was evaluated as partial replacement for fishmeal in extruded diets for rainbow trout, with particular emphasis on the effect on growth performance and apparent digestibility coefficient (ADC) of protein, lipids, carbohydrates, and energy. Effect on muscle fatty acid composition was also evaluated. All diets were formulated to be isonitrogenous and isoenergetic and to contain approximately 45% crude protein and 5.5 kcal energy g/diet. Diets were formulated to include whole lupin seed meal at 0, 10, 15, and 20%. Triplicate groups of fish weighing 65.9 ± 15.1 g on average were fed twice a day until apparent satiation during 12 wk. Growth, feed intake, hepatosomatic index, hepatic histology, proximate composition of whole body, and muscular fatty acid profile were determined. Growth and feed utilization were similar in all treatments and whole-body composition did not vary among treatments. Polyunsaturated fatty acids of the n-6 and n-3 series remained constant in muscle as the amount of lupin in diets increased. Furthermore, the ADCs were similar among all diets. These results suggest that inclusion of whole lupin seed meal up to 20% in extruded diets for rainbow trout do not have any negative effect on growth, feed performance, or flesh quality. © Copyright by the World Aquaculture Society 201

Efectos del autoclave sobre el coeficiente de digestibilidad aparente de la harina descascarada de arveja (Pisum sativum) en trucha arco iris (Oncorhynchus mykiss)

The effect of autoclaving on the nutrients’ apparent digestibility coefficient (ADC), digestible protein and energy of pea seed meal (P. sativum) fed to Rainbow trout (O. mykiss) was examined. Two samples of the pea meal were autoclaved at 121ºC and 1.1 atm for 5 min (5’APM) or 15 min (15’APM), respectively. A third sample, used as control, was not treated (RPM). One reference diet (Basal diet) and 3 experimental diets were elaborated and labelled based on autoclaving time applied to the ingredient (RPM, 5’APM and 15’APM). The four diets were assigned using a completely randomised design, with each treatment having three replicates. 12 tanks were stocked each with 15 trouts with an average weight of 235 ± 10.4 g. Faeces were collected over a 7-day period using a settlement column and pooled within the tank. ADCs were determined using chromium oxide (Cr2O3) as an inert digestibility indicator. No significant differences (P>0.05) regarding protein ADC were found among all treatments. On the other hand, dry matter, energy and nitrogen free extract (NFE) ADC showed significant differences (p0,05) con respecto a los CDAs de proteína entre los tratamientos. Por otra parte, los CDAs de materia seca, energía y extracto no nitrogenado (ENN) fueron estadísticamente diferentes (P<0,05). Los resultados demostraron que el tratamiento 5’APM incrementó el CDA de materia seca, además de energía y proteína digestible de la harina descascarada de arveja

Inclusion of macroalgae meal (Macrocystis pyrifera) as feed ingredient for rainbow trout (Oncorhynchus mykiss): Effect on flesh fatty acid composition

The use of macroalgae as an additional component in animal feeding has been studied. However, information on how it could influence muscle composition of fish body is scarce. This study evaluates four diets with different macroalgae inclusion levels (0%, 1.5%, 3% and 6%) to test the effect on body fatty acid composition of rainbow trout. Tanks with a volume of 600 L were stocked with 60.6 ± 7.9 g fish at a density of 45 individuals tank-1 and fed for 124 days. At the end of the experiment there were not significant differences (P&lt;0.05) in muscle proximate composition among fish fed the different treatments. However, it was determined that inclusion of 3% and 6% of macroalgae meal resulted in a significant increase (P&lt;0.05) of polyunsaturated fatty acids (PUFAs) in muscle. In summary, macroalgae meal in rainbow trout diets do not enhance the quantity of protein and lipid contents at muscle level but an addition of 3-6% might contribute to increase the level of PUFAs, specially EPA, DHA and LIN. Thus, use of macroalgae meal might help to increase lipid quality content in the final product due the beneficial effects of PUFAs for human health

Puye farming (Galaxias maculatus), in a closed recirculation system

Este estudio muestra los antecedentes del cultivo larvario del puye, Galaxias maculatus (Jenyns), un pequeño pez de aguas frías del hemisferio sur. Para el cultivo, larvas recién eclosionadas fueron puestas en estanques de 500 litros de volumen útil. Las larvas fueron alimentadas utilizando una secuencia de rotíferos, Arfemia spp. y alimento inerte. Durante todo el sistema de producción que duró 150 días, fue necesario realizar un desdoble y una separación por tamaño. Los resultados muestran que esta especie puede alcanzar su tamaño comercial (4 a 6 cm) en seis meses aproximadamente, si es cultivado en un sistema intensivo como el propuesto. Los resultados muestran que las larvas de Galaxias maculatus, responden satisfactoriamente a la secuencia de alimentación que incluye rotiferos, Arfemia spp. y alimento inerte, en un sistema intensivo de producción como el estudiado.This study reports data on the larval culture of the "puye", Galaxies maculatus (Jenyns), a small cold water fish occurring in the Southern Hemisphere. For this culture, recently enclosed larvae were placed into 500 liter tanks and fed first with rotifers, then with Artemia spp., and finally with prepared feed. Over the growth period of 150 days, several separations of the fishes were necessary based on size differentials. Results suggested this species would reach a commercial size of 4 to 6 cm in about six months using the intensive system proposed. The larvae of this fish responded well to the feeding sequence described, within the intensive culture system studied

Productive performance of extruded and pelleted diets in intensive rearing of rainbow trout, Oncorhynchus mykiss.

Documento presentado en las XVIII jornadas de Ciencias del Mar realizado en Iquique, 4-8 de Mayo de 1998.En este trabajo se evalúa el efecto de una dieta pelletizada y una extruída en el crecimiento, ganancia en peso, índice de conversión (considerando el peso total, el peso eviscerado y el peso eviscerado sin cabeza) y deposición de lípidos (carcasa, músculo y visceras) de la trucha arcoiris. Los peces fueron cultivados durante 127 días (26 abril al 30 agosto) en tanques circulares de fibra de vidrio de 2,5 m3 con 1,5 cambios por hora, temperatura promedio de 12,5-C, fotoperiodo natural y alimentación ad-libitum. En cada tanque se colocaron 202 peces con un peso y talla promedio de 83,7+15,6g y 19,2*1,0cm,respectivamente. La densidad promedio inicial fue de 6,76kg/m3. Cada tratamiento tuvo una replica y los resultados fueron analizados a través de una ANOVA (P<0,05) y el test de comparación de medias de Tukey. Los peces alimentados con la dieta extruída incrementaron 2 10,25*1,76% mientras que los alimentados con la dieta pelletizada incrementaron 179,67&0,94% existiendo diferencias altamente significativas entre los valores. La tasa de crecimiento específica para la dieta extruída (1,171 %) fue significativamente mayor que la lograda con la dieta pelletizada (1,071%). La mortalidad alcanzada con la dieta extruída fue de 1,76%0,26% y con la dieta pelletizada 1,75*0,75%. Se encontraron diferencias significativas entre las densidades alcanzadas al final del ensayo (pelletizada 24,05*0, 19kgím3 y extruída 27,11*0, 10kg/m3). Los índices de conversión mostraron diferencias significativas entre las dietas ensayadas, excepto cuando el cálculo se hizo con el peso sin cabeza y sin visceras. El costo del alimento por kilo de trucha entera producida fue US$1,22 para la dieta pelletizada y de US$1,28 para la dieta extruída. Cuando se considera el costo del alimento por kilo de trucha sin visceras producida, los valores subieron a US$1,46 y US$1,5 1 para el pellet y extruído respectivamente. Ahora, si se considera el costo en alimento para producir un kilo de trucha sin cabeza y eviscerada, los valores suben a US$1,78 para el pellet y US$1,88 para el extruído. Las truchas alimentadas con dietas pelletizadas incrementaron los lípidos en 84%, 7,35% y 51,98% en pescado entero, músculos y visceras respectivamente. Mientras que, el incremento de los lípidos en las truchas alimentadas con dieta extruída fue de 107.1% para el pescado entero, 3 1.9% en el músculo y 82,6% en vísceras. Considerando el costo de las dietas extruída y pelletizada y la distribución de los lípidos en el cuerpo del pez durante el periodo de cultivo, se discute la conveniencia del uso de una u otra dieta.In this paper is evaluated the effect of a pelleted diet and a extruded diet, on the growth rate, weight gain, food conversion (considering the total weight, the eviscerated weight and the without head and viscera weight) and lipids deposition in carcass, muscle and vicera in rainbow trout. Fish were fed ad-libitum during 120 days in circular fiberglass tanks of 2.5 m3 with a water exchange rate of 1.5 volumesíh and average temperature of 12.5-C. In each tank were put 220 fish of 83.7*15.6g and 19.2*1.0cm. The initial density was 6.77kg/m3. Each treatrnent with two replications, and the results were analyzed through an ANOVA (Pc0.05) and the mean multiple comparations Tukey test. The fish fed with extruded diet increased 210.25%1.76% while fed them with the pelleted diet increased 179.67*0.94% existing differences highly significatly. The specific growth rate for the extrued diet (1.171%) was significantly greater than achieved it with the pelleted diet (1.071%). There were found significant differences between the reached final densities (pelleted diet 24.05h0.1 9kgím3 and extruded diet 27.11*0.10kg/m3). The food conversion show significant differences between the diets tested in the different calculated weight, except for the without head and viscera weight. The food cost by Kg of whole fish was US$1.22 for the pelleted diet and US$1.28 for the extruded diet. When it is considered the food cost by eviscerated weight, the value rised to US$1.46 and - US$1.5 1 for the pelleted diet and extruded diet, respectively. If it is considered the food cost to produce a Kg trout without head and viscera, the value rised to US$1.78 for the pelleted diet and US$1.88 for the extruded diet. The trout fed with pelleted diet increased the lipid contents with respect to the initial content in 84%, 7.35% and 5 1.98% in whole fish, muscles and viscera, respectively. While, the increase of the lipids in the trout fed with extruded diet was of 107.1 % for the whole fish, 3 1.9% in the muscle and 82,6% in the viscera. Considering the cost of the extruded and pelleted diets and the distribuición of the lipids in the body of the fish during the period of cultivation is discussed the convenience of the use of one or the other diet

Feeding high inclusion of whole grain white lupin (Lupinus albus) to rainbow trout (Oncorhynchus mykiss): Effects on growth, nutrient digestibility, liver and intestine histology and muscle fatty acid composition

The effect of dietary inclusion of whole grain white lupin (Lupinus albus) on growth performance, histology, muscle fatty acid composition and nutrient digestibility was investigated in an 11-week growth and a 4-week digestibility trial with rainbow trout (initial body weight of 54.0 ± 6.2 and 181.9 ± 3.4g respectively). Four experimental extruded diets were formulated to contain 0%, 30%, 40% and 50% of whole grain lupin and fed to triplicate groups of fish twice a day until apparent satiation. Faeces were collected daily from each digestibility tank by decantation. No significant trends were observed with respect to growth, feed utilization, apparent digestibility coefficients or whole-body composition (P&gt;0.05). Conversely, increasing levels of dietary lupin led to significant decreases in the Hepatosomatic index (R2=0.75, P&lt;0.05) and slight lipid infiltration into hepatocytes and enterocytes. Muscle fatty acid compositions were slightly affected by the dietary treatment. Polynomial regression of dietary inclusion of lupin and muscle fatty acid concentrations showed an increase in C18:1n-9, C18:2n-6 and C18:3n-3 and a decrease in C20:5n-3 with increasing dietary lupin level. These results demonstrated that whole grain lupin can be included up to 50% in commercial rainbow trout diets without negative effects. © 2010 Blackwell Publishing Ltd

Biological bases for whitebait culture Galaxias maculatus (Jenyns, 1842): a review

Galaxias maculatus (Jenyns, 1842) es un pez gourmet de importancia comercial cuyas pesquerías están sobre-explotadas, siendo esencial el estudio de su biología para desarrollar su tecnología de cultivo (galaxicultura), que se encuentra en etapa piloto. Los objetivos de éste trabajo son: 1) entregar una síntesis de la información de la literatura sobre la biología de la especie, y 2) identificar la carencia de conocimiento científico y puntos críticos para el desarrollo de su tecnología de cultivo comercial. G. maculatus es un pequeño pez carnívoro, con poblaciones eurihalinas diferenciadas en diadrómicas y dulceacuícolas. Las poblaciones diadrómicas desovan en los estuarios y la larva migra al mar, retornando a la edad de seis meses para metamorfosearse en adulto. Son escasos los estudios de su sistemática, poblaciones y estado larvario en aguas chilenas, pero los correspondientes a alimentación, reproducción y enfermedades son más numerosos. Las hembras de un año desovan, aproximadamente, 1.200 huevos adhesivos pero un número importante muere después del primer desove (40%). La especie tiene un crecimiento rápido (1,1% dia-1) y alto metabolismo, con un promedio de vida de dos años. Se puede cultivar en cautividad, desovar, incubar sus huevos y obtener larvas; los adultos comen starter pelletizado de salmón y crecen en estanques. El protozoo ciliado Ichtyophthirius multifilis (ich) produce altas mortalidades, en ejemplares en cautiverio, que pueden ser controladas con baños de sal. Los problemas de investigación a resolver para una futura piscicultura comercial son: identificar y seleccionar las poblaciones adecuadas para cultivo, aumentar el número de huevos desovados por hembra, desarrollar alimentos para larvas y reproductores, y controlar las enfermedades ectoparasitarias. El punto crítico es la masificación de la producción mediante el mejoramiento de las técnicas de reproducción y larvicultura.Galaxias maculatus (Jenyns, 1842), is a gourmet fish of great commercial importance with overexploited fisheries. So, studies of its biology are essential in order to develop a technology for its cultivation (galaxiculture), which is at a pilot stage. The goals of this work are: 1) to provide a synthesis of the literature information on the biology of the species, and 2) to identify the lack of scientific knowledge and critical points for the development of a technology for mass commercial culture. G. maculatus is a small carnivorous fish with euryhaline populations differentiated between diadromic and freshwater. Diadromic populations spawn in the estuaries, and then the larvae migrates to the sea, returning aged 6 months and metamorphosing into adults. Studies of their systematic, populations and larvae stage in Chilean waters are scarce, but studies on feeding, reproduction and diseases are more numerous. One year old females lay about 1,200 adhesive eggs and an important number of them die after the first spawning (40%). G. maculatus has rapid growth (1.1% day-1) and a high metabolism, with an average life of 2 years. They can be cultivated in captivity, spawn and incubate their eggs to obtain larvae; adults eat salmon starter pellets and grow in tanks. The ciliate protozoa Ichtyophthirius multifilis (ich) produces high mortality in larvae and adults in confinement; mortality can be controlled with salt bath. The problems to be solved by research for future commercial fish farming are: recognising and selecting suitable populations for cultivation; increasing the number of eggs spawned by females; develop suitable diets for larvae and broodstock; and controlling ectoparasitic diseases. The critical point is achieving mass production by improving the techniques of reproduction and larviculture

Lipid and fatty acid composition during embryo and larval development of puye Galaxias maculatus Jenyns, 1842, obtained from estuarine, freshwater and cultured populations

Galaxias maculatus eggs and larvae obtained from broodfish captured either in an estuarine or a freshwater environment, as well as from cultured broodstock were analysed to compare their lipid and fatty acid profiles. Results showed a lower lipid content in embryos and larvae from estuarine populations than those from fresh water, denoting the influence of environmental conditions. The n-3:n-6 ratio was higher in eggs from estuarine and cultured populations, being in the range of marine fishes, whereas for eggs from freshwater fish was lower and typical of freshwater fishes. The polyunsaturated fatty acids (PUFA), particularly docosahexaenoic acid (22:6n-3) and eicosapentaenoic acid (20:5n-3), were higher in eggs and larvae of broodstock coming from culture or estuarine environments than in those from fresh water. Moreover, these fatty acids markedly increased after hatching in larvae coming from estuarine populations, suggesting the effect of the environment on fatty acid profiles to physiologically prepare the larvae to adapt to higher salinity conditions. Linoleic acid (18:2n-6) content was higher in fresh water fish and its reduction during embryo and larval development was accompanied by a significant increase of arachidonic acid (20:4n-6), which was not observed in embryos or larvae from broodstock fish from estuary or aquaculture origin. Both environment and diet of broodstock fish affected lipid and fatty acid composition of G. maculatus embryo and larvae as well as their changes during development