Effect of replacing dietary fish oil with vegetable oils on the fatty acid composition of muscle tissue of juvenile California halibut (Paralichthys californicus)

"Se estudió el reemplazo total de aceite de hígado de bacalao por aceites vegetales en las dietas de juveniles de lenguado de California (Paralichthys californicus). Se formularon cinco dietas con aceites de oliva, maíz, linaza y dos combinaciones de linaza y maíz, y se compararon con una dieta testigo que contenía aceite de hígado de bacalao. Después de 12 semanas de experimentación se observó un crecimiento mayor en los ejemplares alimentados con la dieta testigo; sin embargo, no hubo diferencias significativas en crecimiento y supervivencia entre las dietas experimentales. Los ácidos grasos provenientes de los aceites de linaza, maíz y oliva fueron los más acumulados en los tejidos, incrementando en proporción al total de ácidos grasos. Una reducción de 20:5n-3 y 20:4n-6 en presencia de altos niveles dietéticos de 18:3n-3 y 18:2n-6 sugiere que, como en la mayoría de los peces, la síntesis de 18:3n-3 a 20:5n-3 y de 18:2n-6 a 20:4n-6 es muy baja o inexistente. Aun cuando el contenido de 22:6n-3 en el músculo de los ejemplares alimentados con la dieta testigo fue aproximadamente de 2.0 a 2.5 veces más alto que en el de los ejemplares alimentados con las dietas experimentales, no se observaron diferencias significativas. Un decremento proporcional de 20:5n-3 en comparación con todos los ácidos grasos y la ausencia de un incremento en el tejido sugiere que este ácido graso se utilizó en la síntesis de 22:6n-3. Las reducciones significativas en el nivel de 20:5n-3 indican que si se hubiera realizado el experimento durante un periodo de tiempo más largo, se hubiera llegado a un nivel en donde se registrarían efectos adversos en el crecimiento. Es neCésario realizar más estudios, especialmente sobre los cambios proporcionales y cuantitativos de 20:5n-3 y 22:6n-3 en la composición del tejido muscular.""Total replacement of cod liver oil by vegetable oils in the diets of juvenile California halibut (Paralichthys californicus) was analyzed. Five diets were formulated with olive oil, corn oil, linseed oil, and two combinations of linseed oil and corn oil, and compared with a control diet containing cod liver oil during a 12-week feeding experiment. Highest growth was observed in fish fed the control diet; however, no significant differences in growth and survival were observed among the dietary treatments. The fatty acids from linseed, corn, and olive oils were the most accumulated in the tissue, increasing in proportion to the total fatty acids. Reduced levels of 20:5n-3 and 20:4n-6 in the presence of high dietary levels of 18:3n-3 and 18:2n-6 suggest that, as in most marine fishes, synthesis of 18:3n-3 to 20:5n-3 and of 18:2n-6 to 20:4n-6 is either very limited or does not occur. Although the content of 22:6n-3 in the muscle of fish fed the control diet was approximately 2.0 to 2.5 times greater than that in the muscle tissue of fish fed the experimental diets, no significant differences were detected. A proportional decrease in 20:5n-3 among all fatty acids and a lack of an increase in body tissue suggest that this fatty acid was being used to synthesize 22:6n-3. The significant reductions in the level of 20:5n-3 indicate that if the experiment had been conducted over a longer period of time, a level would eventually be reached whereby the dietary deficiency would presumably be reflected by an adverse effect on growth. Additional research is needed, particularly regarding the proportional and quantitative changes of 20:5n-3 and 22:6n-3 in the composition of the muscle tissue.

Protein retention assessment of four levels of poultry by-product substitution of fishmeal in rainbow trout (Oncorhynchus mykiss) diets using stable isotopes of nitrogen (δ15N) as natural tracers

This is second part from an experiment where the nitrogen retention of poultry by-product meal (PBM) compared to fishmeal (FM) was evaluated using traditional indices. Here a quantitative method using stable isotope ratios of nitrogen (δ15N values) as natural tracers of nitrogen incorporation into fish biomass is assessed. Juvenile rainbow trout (Oncorhynchus mykiss) were fed for 80 days on isotopically distinct diets in which 0, 33, 66 and 100% of FM as main protein source was replaced by PBM. The diets were isonitrogenous, isolipidic and similar in gross energy content. Fish in all treatments reached isotopic equilibrium by the end of the experiment. Two-source isotope mixing models that incorporated the isotopic composition of FM and PBM as well as that of formulated feeds, empirically derived trophic discrimination factors and the isotopic composition of fish that had reached isotopic equilibrium to the diets were used to obtain a quantitative estimate of the retention of each source of nitrogen. Fish fed the diets with 33 and 66% replacement of FM by PBM retained poultry by-product meal roughly in proportion to its level of inclusion in the diets, whereas no differences were detected in the protein efficiency ratio. Coupled with the similar biomass gain of fishes fed the different diets, our results support the inclusion of PBM as replacement for fishmeal in aquaculture feeds. A re-feeding experiment in which all fish were fed a diet of 100% FM for 28 days indicated isotopic turnover occurred very fast, providing further support for the potential of isotopic ratios as tracers of the retention of specific protein sources into fish tissues. Stable isotope analysis is a useful tool for studies that seek to obtain quantitative estimates of the retention of different protein sources. © 2014 Badillo et al

Isótopos estables ( ?15 N ) como herramienta para medir la calidad de alimentos comerciales para lobina rayada ( Morone saxatilis ) en jaulas marinas

Aquafeed quality for striped bass (Morone saxatilis) was evaluated under commercial conditions in sea cages using stable isotopes as tracers for nitrogen. Using a crossover experimental design, fish that were fed during 270 days with aquafeed A was switched to aquafeed B during the following 160 days. Samples of aquafeeds and of muscle, and liver tissues were analyzed before and during feeding with aquafeed B. The isotopic value from diet A and muscle and liver tissues after being fed during 270 days were 10.3, 14.6 and 13.1 resulting in a discrimination factor of 4.3 and 2.7 for muscle and liver. At day 90 and 160 the discrimination factor reach the equilibrium both for muscle and liver tissues (2.3 and 0.0). It was concluded that diet B hadbetter quality as a result of a lower discrimination factor than that observed with diet A. The nitrogen stable isotope is a reliable tool to evaluate aquafeeds quality under commercial conditions where the other estimations like feed intake and apparent digestibility are difficult to obtain.La calidad entre dos alimentos comerciales (A y B) se evaluó utilizando isótopos estables como trazadores de la retención de nitrógeno (?15N) en lobina rayada (Morone saxatilis) mantenidas en jaulas marinas. Con base en un diseño cruzado, se utilizaron peces que habían sido alimentados durante 270 días con el alimento A, mismos que fueron cambiados al alimento B durante otros 160 días. Se analizaronmuestras de los alimentos comerciales y de tejido de músculo e hígado antes y durante la alimentación con el alimento comercial B, para determinar su composición química e isotópica. El valor isotópico de losalimentos comerciales, músculo e hígado, al término de la alimentación con el alimento A fue de 10.3, 14.6 y 13.1, lo que refleja un factor de discriminación para músculo e hígado de 4.3 y 2.7, respectivamente. Al hacer el cambio al alimento B (11.09), se observó una reducción en los valores isotópicos. Para los días 90 y 160, los valores de discriminación ya eran casi constantes tanto para músculo como para hígado (2.3 y 0.0). Se concluye que el alimento B presentó una mejor calidad al incorporarse con un menor factor de discriminación que lo observado con el alimento A. La técnica de isótopos estables demostró ser una herramienta útil para monitorear la calidad del alimento bajo condiciones comerciales, ya que mide directamente la eficiencia de la retención del nitrógeno, mientras que en otras pruebas como las de consumo y de digestibilidad aparente, es difícil de obtener

New findings in the searching of an optimal diet for the axolotl Ambystoma mexicanum: protein levels

Objective: To determine the protein nutritional requirements in juvenile axolotls (Ambystoma mexicanum) based on four isocaloric diets (8% lipids) with 30, 35, 30, and 45% protein.Design/methodology/approach: Six axolotls were used per test, during a period of 81 days. The diets were prepared using fishmeal as a protein source and fish oil as a lipid source. The feed was supplied every 48 h with 4% of the weight of the biomass of organisms per experimental reservoir. Four biometrics were performed throughout the experiment and growth parameters were determined: height, weight gained per day, specific growth rate, survival, Fulton’s K, and protein efficiency rate. The digestibility of each of the diets was also determined. Results: There were significant differences in the growth and survival of the axolotls, the diet with 45% protein showed the best growth results. Limitations/implications: No more protein levels could be tested, due to the number of organisms available for bioassays. Findings/conclusions: Diets for the axolotl (A. mexicanum) containing 45% protein level promote good development and survival. This allows for improved cultivation and management plans for the species

Total or partial replacement of fishmeal with soybean meal in the diet of the Pacific fat sleeper Dormitator latifrons juveniles

Groups of Dormitator latifrons in triplicate (4.1 ± 2.0 g and 6.2 ± 1.0 cm) were fed experimental diets containing four levels of substitution of fishmeal (FM) by soybean meal (SM) (0, 40, 70, and 100%, respectively). The diets were formulated to be isoproteic (35% crude protein) and isolipidic (8.0% crude lipids). The effect of each treatment on growth was evaluated and its implications on the cost of feeding. After 60 days of feeding, there were no significant differences in the fish's proximate composition (P < 0.05). There were no significant differences between the diets (P < 0.05) in the evaluated biological indices: total growth increase (TGI), specific growth rate (SGR), thermal growth coefficient (TGC), and survival (%). Feeding costs decreased significantly as the proportion of soybean meal in the diet increased. The results indicated that substituting FM by up to 100% of SM can promote adequate growth in D. latifrons without affecting body composition and survival while also reducing operative costs during the fattening process.Fil: Badillo Zapata, Daniel. Universidad de Guadalajara; MéxicoFil: Musin, Gabriela Eliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Palma Cancino, David J.. Universidad de Guadalajara; MéxicoFil: Guerrero Galván, Saúl R.. Universidad de Guadalajara; MéxicoFil: Chong Carrillo, Olimpia. Universidad de Guadalajara; MéxicoFil: Vega Villasante, Fernando. Universidad de Guadalajara; Méxic

Efecto de la salinidad sobre la frecuencia ventilatoria branquial de Dormitator latifrons (Richardson, 1984)

Dormitator latifrons habita en un amplio intervalo de salinidades producto de su ciclo migratorio y reproductivo. Nuestro objetivo fue evaluar el tiempo de respuesta fisiológica y la sobrevivencia al cambio salino en condiciones de laboratorio. Se midió la frecuencia ventilatoria branquial basal de organismos que se encontraban en 33 ups (AS) y en agua dulce 0.3 ups (AD). Se contabilizo la frecuencia ventilatoria branquial de organismos que fueron transferidos AD-AS e inversamente AS-AD (15, 25, y 33 ups), por triplicado, durante 1 minuto, 1, 4, 24 y 48h. Se encontraron diferencias estadísticas (p<0.05) en los peces transferidos de AD-AS y AS-AD al primer minuto con respecto a FVB basal. En todos los tratamientos una hora después de ser expuesto al cambio salino regresaron a la FVB basal. Se registro un 100% de sobrevivencia en todos los tratamientos. D. latifrons presenta una rápida respuesta fisiológica a cambios bruscos de salinidad

First attempt to fill gaps in the feeding of the axolotl

Objective: To determinate the attractability of four oils, fish, chicken, krill, and red crab (Pleuroncodes planipes) for Ambystoma mexicanum juveniles, evaluating their feeding behavior using a Y aquarium.Design/Methodology/Approach: Ten axolotls were used per test, fasted for 48 h. Gels with oils were prepared using gelatin and poured into petri dishes and refrigerated until gelation. A recording of the test was made using two video cameras. In the feed chamber the gelled oil was placed and allowed to stand for 15 min. On the other chamber a gelled disk with no other ingredient than gelatin and water was placed. The video recording began once the 15 min of gel permanence had finished, removing the barrier so that the axolotls could move through the rest of the aquarium. All tests were carried out with a recording time of 30 min.Results: Fish oil demonstrated a lower attraction effect compared to krill, red crab and chicken oils (P0.05), while chicken oil (30.001.73) doubled the attractive effect of krill oil (16.001.00).Limitations of the study/implications: It was necessary to condition a room with controlled environmental temperature for A. mexicanum (181 °C).Findings/Conclusions: Krill and chicken oil are good feeding effectors for A. mexicanum causing positive feeding behavior. The use of chicken oil is desirable because of its low cost compared to krill

Survival of the prawn Macrobrachium tenellum (Smith, 1871) in confinement with the native fish Dormitator latifrons (Richardson, 1844)

Objective: The aim of this study was to test the survival of Macrobrachium tenellum in different confinement conditions with Dormitator latifrons. Design/methodology/approach: Using wild specimens acclimated to captive conditions of both species, three trials of different proportion were performed with treatments consisting in the presence/absence of food and shelters. Prawn/fish proportion for the assays were: 15/15 for T1, 15/3 for T2 and 10/3 for T3. In assays T1 and T2 juvenile prawns and fish were used, while in T3 post-larvae prawns and pre-juvenile fish were used. To test the survival with or without fed, it was schedule a four-day feeding ad libitum period, following by a two-day fed depravation period in all the assays. Results: In assays with juveniles of M. tenellum the survival rate was superior to 80% with or without shelter, when T1 showed 97-100% survival; meanwhile T3 presented a 56.67 % of survival, suggesting it’s necessary to use only juvenile prawns in co-culture systems. The use of shelters and fed deprivation had no significant effects on the survival of prawns. Limitations on study/implications: M. tenellum is an important aquatic resource for the central Mexican Pacific, region in which the D. latifrons is a representative native fish with a developing aquaculture. A polyculture or co-culture system with these species can accelerate the sustainability of both species productions. Findings/conclusions: The results suggest this polyculture system may be feasible, and longer duration culture are recommended.Objective: The aim of this study was to test the survival of Macrobrachium tenellum in different confinement conditions with Dormitator latifrons. Design/methodology/approach: Using wild specimens acclimated to captive conditions of both species, three trials of different proportion were performed with treatments consisting in the presence/absence of food and shelters. Prawn/fish proportion for the assays were: 15/15 for T1, 15/3 for T2 and 10/3 for T3. In assays T1 and T2 juvenile prawns and fish were used, while in T3 post-larvae prawns and pre-juvenile fish were used. To test the survival with or without fed, it was schedule a four-day feeding ad libitum period, following by a two-day fed depravation period in all the assays. Results: In assays with juveniles of M. tenellum the survival rate was superior to 80% with or without shelter, when T1 showed 97-100% survival; meanwhile T3 presented a 56.67 % of survival, suggesting it’s necessary to use only juvenile prawns in co-culture systems. The use of shelters and fed deprivation had no significant effects on the survival of prawns. Limitations on study/implications: M. tenellum is an important aquatic resource for the central Mexican Pacific, region in which the D. latifrons is a representative native fish with a developing aquaculture. A polyculture or co-culture system with these species can accelerate the sustainability of both species productions. Findings/conclusions: The results suggest this polyculture system may be feasible, and longer duration culture are recommended

Palatability of animal oils included in the diet of the Mexican axolotl and its effect on growth and survival

Objective: The growth, survival, and condition factor of Ambystoma mexicanum juveniles fed with three commercial feed-based diets coated with different animal oils as potential palatability enhancers were evaluated. Methodology: Three diets were prepared using commercial feed coated with fish, chicken, and krill oil. The experiment lasted 81 days, the food was provided to the axolotls (6 per experimental unit, in triplicate) every 48 h, at 4% of the total biomass. The total weight of each experimental unit was recorded every 15 days, at the end of the experiment individual weight and height and survival were recorded. The following variables were calculated: Fulton’s K, specific growth rate, coefficient of variation of final weight and size heterogeneity. Results: All three treatments showed an increase in total biomass, with a trend towards better performance in chicken and fish oil treatments compared to krill oil. When performing the statistical analysis, it was found that there were no significant differences among the treatments for any of the variables recorded. Implications: The three oils used in the present study were good palatable agents in the food intake of A. mexicanum. Conclusions: It is recommended to use chicken oil as an attractant additive in the formulation of a specific diet due to its low cos

Efecto de la salinidad en el crecimiento de juveniles de dormitator latifrons (Richardson, 1844)

Dormitator latifrons, a native euryhaline species belonging to the family Eleotridae, is distributed from southern California to Peru. This research study is a contribution to evaluate the effect of different salinity concentrations (0, 10, 20 and 33 UPS) on growth, survival, hematology and blood chemistry. The results show statistical difference (P &lt; 0.05) in the treatment at 10 UPS in weight per individual (91.5 ± 7.5 g), final biomass (2286.3 ± 188.3 g) and weight gain (55.5 ± 5.9 g). In the hematological parameters, statistical differences (P &lt; 0.05) were found in the total erythrocyte count (× 106), with the highest value (4.33 ± 0.49) in the 20 UPS treatment and the lowest value (2.77 ± 0.13) in the 0 UPS treatment; survival was greater than 90.7% in all treatments. Finally, it can be concluded that the 10 UPS treatment had a greater influence on the weight (g) of Dormitator latifrons juveniles, and the GP and EA growth rates increased proportionally in the 10 UPS treatment. The results show that salinity influences the growth of the organisms despite the fact that Dormitator latifrons is a euryhaline organism. It was observed that the highest growth occurred at a salinity of 10 UPS.Dormitator latifrons, es una especie nativa eurihalina, perteneciente a la familia Eleotridae que se encuentra distribuido desde el sur de California hasta Perú. Este estudio de investigación es una contribución para evaluar el efecto de diferentes concentraciones de salinidad (0, 10, 20 y 33 UPS) en el crecimiento, su- pervivencia, hematología y química sanguínea. Los resultados muestran diferencia estadística (P &lt; 0.05) en el tratamiento a 10 UPS en peso promedio por individuo (91.5 ± 7.5 g), biomasa final (2286.3 ± 188.3 g) y ganancia en peso (55.5 ± 5.9 g). En los parámetros hematológicos se encontraron diferencias estadísticas (P &lt; 0.05) en el recuento total de eritrocitos (× 106), en el tratamiento a 20 UPS se presentó el mayor valor (4.33 ± 0.49) y en el tratamiento a 0 UPS el menor valor (2.77 ± 0.13), la supervivencia fue mayor al 90.7% en todos los tratamientos. Finalmente, se puede concluir que el tratamiento a 10 UPS generó mayor influencia en el peso (g) de juveniles de Dormitator latifrons, asimismo las tasas de crecimiento GP y EA incrementaron proporcionalmente en el tratamiento a 10 UPS. Por lo cual se considera esta especie con potencial acuícola, los resultados, muestran que la salinidad influye en el crecimiento de los organismos a pesar de que Dormitator latifrons es un organismo eurihalino. Se observó que el mayor crecimiento se presentó a una salinidad de 10 UPS