An experiment were conducted to evaluate The effect of feeding frequencies and stocking size on growth and feed conversion ratio (FCR) of rainbow trout (O. mykiss) in brackish water for 102 days. Three stocking sizes (10, 25 and 40 g/fish) of rainbow trout and three feeding frequencies (feeding fish twice, three times and four times per day) were examined as the same time. Fish were fed at a restricted feeding program according to the rainbow trout standard table in the definite times during the light period. The results showed that in the group with 10 g initial weight increasing the feeding frequency, some growth factors like final weight, daily growth, and weight gain. But the other factors such as food conversion rate (FCR) and specific growth rate (SGR) decrease. It means in this group (10 g) two times feeding per day is not enough for an acceptable growth rate. In the two other groups with (initial weight 25 and 40 g) although by increasing the feeding frequency, some growth factors a little increase but these differences in 95% level (p،ـ0.05) are not significant. Therefore in rainbow trout culture with initial weight at least 25 g two times feeding per day was enough. The results of carcasses analysis of fish, showed that by increasing the feeding frequency there were no significantly difference at 95% level between the body compositions in all of treatments. With connivance of feeding frequencies, the best FCR was in the group with 10 g initial body weight and there was not any significant difference in SGR. So according to the results, it suggests that fish should be stocked with 10 g initial body weight.

En el cultivo de peces, una estrategia de alimentación adecuada es de suma importancia para disminuir costos de producción. Morone saxatilis, es una de las especies con gran potencial económico, no obstante, su cultivo se ve comprometido debido a los escasos estudios relacionados con la alimentación en condiciones locales. El objetivo fue evaluar la frecuencia de alimentación sobre el desempeño biológico, digestibilidad y genes de saciedad en juveniles de M. saxatilis cultivada en agua marina a 21°C durante 56 días. Un total de 708 organismos (con un peso promedio inicial de 21.97 ± 0.26 g) distribuidos aleatoriamente en 12 tanques con una densidad de 59 peces por tanque. Fueron alimentados a saciedad con una dieta comercial Ewos® (54% proteínas, 14% lípidos) con cuatro frecuencias de alimentación; una cada 4 h cuatro veces al día, una cada 12 h dos veces al día, una cada 24 h una vez al día y una cada 48 h una vez cada dos días (Al4h, Al12h, Al24h y Al48h, respectivamente). Los resultados indican que la frecuencia de alimentación influye significativamente en el desempeño biológico, la eficiencia alimentaria, composición muscular y expresión de genes de saciedad en juveniles de M. saxatilis. La frecuencia Al4h presentó mayor ganancia de peso (40.21 ± 1.63 g) y TCE (1.77 ± 0.04 %), mientras que Al48h resultó con un mejor TCA (0.91 ± 0.03 %) y TEP (2.03 ± 0.06 %). En la composición muscular, Al4h mostró mayor porcentaje de proteínas (77.63 ± 1.16 %) y menor porcentaje de lípidos (16.00 ± 1.21 %). En lo que respecta a la expresión de los genes de saciedad (orexina y leptina) sus respuestas varían en función de la frecuencia y alimento ofrecido, donde los peces del tratamiento Al48h resultaron en una mayor expresión de la orexina y los peces del tratamiento Al4h resultaron con una mayor expresión de la leptina. Bajo nuestras condiciones de cultivo, la frecuencia de alimentación adecuada para obtener el mejor crecimiento es Al24h, sin embargo, si se quiere reducir los costos operativos mejorando la eficiencia alimenticia, la frecuencia alimenticia es Al48h. | In the marine fish farming industry, one of the major challenges to reduce costs is related to feeding, prompting the development of strategies to optimize feed utilization. Morone saxatilis is one of the species that has shown great economic potential, however, local culture practices are compromised due to the limited studies related to feeding frequencies. The objective of this study was to evaluate the effect of feeding frequency on the biological performance, feed efficiency, digestibility, and satiety-related genes in juvenile striped bass (M. saxatilis) reared in seawater at 21°C for 56 days. A total of 708 fish (with an initial average weight of 21.97 ± 0.26 g) were randomly distributed into 12 tanks with a capacity of 400 L resulting in stocking densities of 59 per tank. The fish were fed to satiation with a commercial diet Ewos® (54% protein, 14% lipid) under four feeding frequencies, once every 4 h four times per day, once every 12 h twice per day, once every 24 h once per day and once every 48 h (once every two days) (Al4h, Al12h, Al24h, and Al48h, respectively). The results of this research indicate that feeding frequency significantly affected biological performance, feed efficiency, muscle composition, and the expression of genes related to satiety in juvenile striped bass, but not survival or diet digestibility. The Al4h frequency resulted in the highest weight gain (40.21 ± 1.63 g) and SGR (1.77 ± 0.04%). Meanwhile, Al48h resulted in the best FCR (0.91 ± 0.03%) and PER (2.03 ± 0.06%) with lower feed intake (28.37 g). Al4h showed the highest muscle protein content (77.63 ± 1.16%) and the lowest lipid content (16.00 ± 1.21%). As for the expression of satiety genes (orexin and leptin), responses varied with respect to the feeding frequency and feed availability, where fish in the Al48 treatment resulted in higher orexin expression levels while fish in the treatment Al4 resulted in higher leptin expression levels. Under our cultivation conditions, the recommended feeding frequency to increase growth and feed efficiency was Al12h. Nonetheless, if the objective is to reduce operational costs Al48h, is the optimal feeding frequency.

"El efecto de la frecuencia alimenticia en el crecimiento y sobrevivencia de juveniles de langosta de agua dulce Cherax quadricarinatus, fue evaluado en 60 días de cultivo. Grupos de juveniles de acociles (crayfish) con peso inicial de 0.89 ± 0.06 g fueron alimentados con cuatro diferentes frecuencias de alimentación por día: cada 24 h (C1), 12 h (C2), 6 h (C3) y cuatro veces al día (C4) con una dieta con 35% de proteína cruda. Las tasas de crecimiento específico (TCE) de 3.02 y 2.79%/día, muestran que las frecuencias alimenticias C3 y C4 maximizan el desarrollo de juveniles de C. quadricarinatus, obteniendo pesos finales de 4.7 y 5.4 g, biomasas de 253.2 y 311.8 g/m2 , con Factores de Conversión Alimenticia (FCA) de 1.8 y 1.2, respectivamente. Los tratamientos C1 y C2 mostraron un FCA significativamente más alto. El intervalo de sobrevivencia fue de 86.7 a 98.3%, siendo estadísticamente menor para los tratamientos experimentales C1 y C2. Los resultados de incremento en peso de los juveniles de C. quadricarinatus, indican que la frecuencia de alimentación óptima es de al menos tres veces al día. Sin embargo, en términos de biomasa final el tratamiento C4 fue significativamente diferente con respecto a los demás tratamientos. La información obtenida contribuirá a mejorar la comprensión de la dinámica de distribución del alimento y correlacionarla con la condición nutricional y rendimiento en la producción de juveniles de C. quadricarinatus." | "The effect of feeding frequency on the growth and survival of juvenile freshwater crayfish Cherax quadricarinatus with initial mean weight of 0.89 ± 0.06 g was evaluated in a 60-day study. Juveniles were fed with four different feeding frequencies: every 24 h (C1), 12 h (C2), 6 h (C3) and 4 h (C4), with a 35% crude protein diet. Specific Growth Rates (SGR) of 3.02 and 2.79%/day showed that feeding frequency treatments C3 and C4 maximize growth of juvenile C. quadricarinatus, reaching final mean weights of 4.7 and 5.4 g, biomasses of 253.2 and 311.8/m2 , and Feed Conversion Ratios (FCR's) of 1.8 and 1.2, respectively. Treatments, C1 and C2 showed significantly higher FCR’s. Survival ranged from 86.7 to 98.3%, and was statistically different among the experimental treatments, except for organisms fed with C1 and C2. Final weights of juvenile C. quadricarinatus showed that a feeding frequency of at least three times a day (C3) was significantly better. However, in terms of biomass, treatment C4 was better. The information obtained will contribute to improve the understanding of the dynamics of distribution of feeds and to correlate it with the nutritional condition of juvenile C. quadricarinatus."