ABSTRACT: Lipids requirement of tropical gar Atractosteus tropicus prejuveniles and juveniles was evaluated on growth, survival, chemical composition and apparent digestibility coefficient (ADC). Four semi-purified experimental diets (5, 10, 15 and 20% of lipids) were obtained with a mix of menhaden oil and soybean lecithin (2:1 ratio). Two trials were carried out, first with 600 prejuveniles of 0.5 g (35 days post-hatching, dph) for 56 days, and the second with 160 juveniles of 15 g (two-months-old) for 42 days. In the first trial, 15 (40.8 g) and 20% (40.2 g) lipid diets showed the best weight. Significant differences were obtained in condition factor (CF), daily lipid intake (DLI), hepatosomatic index (HSI), crude protein, ashes, nitrogen-free extract, moisture and ether extract between treatments. In the second trial, fish fed with the 10% lipid diet obtained the highest weight (89.1 g) compared with the other treatments. Significant differences were recorded for weight gain (WG), feed conversion ratio (FCR), specific growth rate (SGR), condition factor (CF), and lipid efficiency rate (LER). Also, significant differences were obtained in crude protein, ether extract, NFE, gross energy, apparent lipid ADC, protein ADC and dry matter ADC. The polynomial models applied to both trials indicated an optimum lipid requirement of 17% for 0.5 g juveniles and of 9% for 15.2 g juveniles.

The effect of the dietary protein level on growth and total body chemical composition of the native cichlid Bay snook (Petenia splendida), masculinized and non-masculinized, was studied. Five semi-purified diets with protein levels 35, 40, 45, 50 and 55% crude protein (CP) were formulated and evaluated by triplicate. Groups of 50 juveniles were each stocked in 70 L tanks and fed to apparent satiation for 42 days trial. At the end, weight gain (WG) (403.41%), body length (BL) (6.58 ± 0.10 cm) and specific growth rate (SRG) (1.67%/day) of the masculinized fish were obtained with the 45% CP diet, and they were significantly different (p = 0.002) from the other treatments. In the case of non-masculinized fish, the 45 and 55% CP treatments showed significant differences (p = 0.00001), with respect to other treatments, with a WG of 398 and 394%, SGR of 1.66 and 1.63%/day, protein productive value (PPV) of 28.91 and 29.21%, and feed conversion rate (FCR) of 1.23 and 1.08 respectively. Protein body composition for masculinized fish was different (p = 0.0001) only for fish fed 35% CP compared with fish at the beginning of the experiment. We conclude that the optimum protein requirement, estimated by the broken-line model for masculinized and non-masculinized P. splendida was 45 and 44.8% PC respectively.

Se evaluó el efecto del nivel de proteína sobre el crecimiento y composición química proximal del cíclido nativo tenguayaca (Petenia splendida) masculinizados y no masculinizados, para lo que se formularon cinco dietas semipurificadas con diferentes niveles de proteína cruda: 35, 40, 45, 50 y 55% PC, colocando 50 peces por tina (70 L) los cuales fueron alimentados a saciedad aparente por 42 días. Al final del periodo experimental, el mayor (p = 0.002) peso promedio (AW, 3.31 ± 0.46 g), longitud (BL, 6.58 ± 0.10 cm), ganancia en peso (WG, 403.41%) y tasa específica de crecimiento (SGR, 1.67%/día) en peces masculinizados se obtuvo para los alimentados con 45% CP. Los peces no masculinizados alimentados con las dietas de 45 y 55% CP fueron estadísticamente diferentes (p = 0.00001) en relación al WG (398 y 394%), SGR (1.66 y 1.63%/día), valor productivo de la proteína (PPV, 28.91 y 29.21%) y factor de conversión alimenticio (FCR, 1.23 y 1.08). La proteína corporal de los peces masculinizados fue estadísticamente diferente (p = 0.0001) para los peces alimentados con 35% CP comparados con los peces al inicio del experimento. Concluimos que el nivel óptimo de proteína estimado con el modelo de línea quebrada para los juveniles masculinizados y no masculinizados de P. splendida fue de 45 y 44.8% CP respectivamente.

Los aminoácidos esenciales y su disponibilidad son importantes en la formulación de alimentos. La digestibilidad de materia seca (DAMS), proteína (DAP) y aminoácidos esenciales (DAAA) fueron determinados (triplicado) para el camarón blanco del Pacífico, Litopenaeus vannamei (15-19g), usando una dieta de referencia con 30% (de cada ingrediente). Los ingredientes evaluados fueron: caseína (CAS), harinas de subproductos avícolas (HSPA) y porcícolas (HSPP), gluten de maíz (GLM) y trigo (GLT), pasta de soya (PS), harinas de sorgo (HS) y trigo (HT). La DAMS y DAP variaron entre 68%-109% y 70%-103%, respectivamente. La DAP en CAS, PS, HT y GLT fue mayor al 90%, en GLM y HSPA superior a 80%; HSPP (76%) y HS (70%) tuvieron menor digestibilidad. Hubo concordancia entre DAP y DAAA, excepto para Arg en GLM, Fen y Leu en HS, Fen en PS y Lis en HT y HSPA. Se encontró una gran variabilidad en la DAMS, DAP y DAAA en los ingredientes, lo que debe ser tomado en cuenta al formular alimentos para camarón.

Apparent digestion coefficients for dry matter, protein and essential amino acids in terrestrial ingredients for Pacific shrimp Litopenaeus vannamei (Decapoda: Penaeidae). Protein quality mainly depends on the essential amino acid (EAA) profile, but also on its bioavailability, because EAA digestibility is generally lower than the analyzed amounts. This information is needed in the aquaculture industry for aquafeed formulation. For this purpose, the apparent digestibility coefficients of dry matter, protein, and essential amino acids of eight feedstuffs of terrestrial origin were determined for the juvenile whiteleg shrimp Litopenaeus vannamei (15-19g), using 1% chromic oxide as an inert marker. A reference diet was formulated and produced in the laboratory. Eight experimental diets were prepared each with 30% of one of the experimental ingredients added to the reference diet: casein, porcine byproduct meal poultry byproduct meal, corn meal, wheat gluten meal, soybean paste, sorghum meal, and wheat meal. The experiment consisted of a single-factor, completely randomized design with three replicates per treatment. Samples of ingredients, diets and feces were analyzed for nitrogen and amino acids. For amino acid assay, we used reverse-phase high performance liquid chromatography. To avoid partial loss of methionine and cystine, samples of ingredients, diets, and feces were oxidized with performic acid to methionine sulfone and cysteic acid prior to acid hydrolysis. The apparent dry matter and protein digestive utilization coefficients varied from 68% to 109% and from 70% to 103%, respectively. Apparent digestibility of protein for casein, soy paste, wheat meal and wheat gluten were very high (over 90%), corn gluten and poultry byproducts meal showed high protein digestibility (over 80%), but porcine byproducts meal and sorghum meal had low digestibility (76% and 70%, respectively). There was a reasonable, but not total, correspondence between apparent protein digestibility and average essential amino acid digestibility coefficients, except for arginine in corn gluten, phenylalanine and leucine in sorghum meal, phenylalanine in soy paste and lysine in wheat meal and poultry by-product meal. The most digestible feed ingredients for whiteleg shrimp were: wheat gluten, wheat meal and soy paste; poultry byproduct meal and corn gluten were less digestible and the lowest digestibility occurred in porcine byproduct meal and sorghum meal. Feedstuffs exhibited great variability in dry matter, protein and amino acid digestive utilization coefficients, which should be considered when formulating shrimp feeds. Rev. Biol. Trop. 58 (4): 1561-1576. Epub 2010 December 01.

The effect of different feed processing methods on the physicochemical properties, and apparent digestibility of cowpea (Vigna unguiculata) meals as ingredients in diets for white shrimp (Litopenaeus vannamei) was investigated. Five experimental cowpea meals were prepared: whole raw (WRC), dehulled (DC), cooked (CC), germinated (GC) and extruded (EXC). The physicochemical properties of the meals were evaluated using differential scanning calorimetry. The meals were included at 15% in diets for L. vannamei (15.4 g) to determine firmness of pellets and in vivo digestibility of nutrients by using chromic oxide as inert marker. Six diets were evaluated: a control diet, and five diets containing the different cowpea meals. Transition enthalpy significantly decreased after thermal treatment, from 6.1 J/g in WRC to 1.4 J/g in CC, and disappeared in EXC. Firmness of pellets varied from 1.1 N in the EXC diet to 2.8 N in the WRC diet. A significant negative correlation between transition enthalpy and carbohydrate digestibility was found. Dry matter, protein, carbohydrate and lipid digestibility of cowpea meals significantly increased after germinating, cooking or extruding. It is concluded that germinated, cooked and extruded cowpea meals are highly digestible for shrimp and that enthalpy of transition is negatively correlated with the digestibility of carbohydrates.

Se evaluó el efecto de diferentes procesos sobre las propiedades fisicoquímicas y digestibilidad aparente de la harina de frijol yorimón (Vigna unguiculata) como ingrediente en alimentos para camarón blanco (Litopenaeus vannamei). Se elaboraron cinco harinas de frijol yorimón: entero crudo (WRC), decorticado (DC), cocido (CC), germinado (GC) y extruido (EXC). Las características térmicas de las harinas fueron evaluadas usando calorimetría diferencial de barrido. Se elaboraron seis alimentos experimentales: un alimento control y cinco alimentos conteniendo 15% de las diferentes harinas de frijol yorimón. A estos alimentos se le determinó firmeza y digestibilidad in vivo de nutrientes para L. vannamei (15.4 g) usando óxido de cromo como marcador inerte. La entalpía de transición decreció después del tratamiento térmico, de 6.1 J/g en la WRC a 1.4 J/g en la CC, y desapareció en la EXC. La firmeza de los alimentos varió de 1.1 N en el alimento con EXC a 2.8 N en el alimento con WRC. Se encontró una correlación significativa negativa entre la entalpía de transición y la digestibilidad de carbohidratos de la harina del frijol yorimón. La digestibilidad de materia seca, proteína, carbohidratos y lípidos de las harinas de frijol yorimón aumentó significativamente con el germinado, la cocción y la extrusión. En el presente estudio se concluye que las harinas de frijol yorimón germinado, cocido y extruido son altamente digeribles para camarón L. vannamei, y la entalpía de transición se correlaciona significativamente con la digestibilidad de los carbohidratos.

A growth trial was conducted to determine the most appropriate temperature and fish density for rearing juvenile spotted sand bass Paralabrax maculatofasciatus under laboratory conditions. The experiment followed a 3 X 2 factorial design with three temperatures (24, 27, and 30°C) and two densities (266 and 400 fish/m³), with three replicates per treatment. Juveniles (mean weight 2.1 g) were fed a semi-moist diet (56% protein and 23% lipids) for 40 days, residing in tanks containing 30 L seawater within an open flow system under laboratory conditions. No effects on survival resulted from these temperatures and fish density conditions were noted. The greatest growth was observed at 27°C and 400 fish/m³, while fish reared at 24°C and 400 fish/m³ and 30°C and 400 fish/m³ had the least growth. The percent apparent daily feed consumption (%ADFC) was significantly different between the two different densities of fish reared at 27°C, but not at the lower or higher temperatures. Feed conversion ratio values were significantly different between fish grown at the intermediate (27°C) and the lower (24°C) temperatures, but not at the higher (30°C) temperature. Therefore, the most appropriate condition for growth of juvenile spotted sand bass cultured in laboratory is 27°C and 400 juvenile fish/m3 (equivalent to 0.84 g/L of initial biomass).

Se realizó un experimento de crecimiento con el objetivo de determinar la temperatura y densidad más apropiadas para el cultivo en laboratorio de juveniles de cabrilla arenera Paralabrax maculatofasciatus. Para ello, se implementó un diseño factorial de 3 X 2 con 3 réplicas por tratamiento, en el que se probaron tres temperaturas (24, 27 y 30°C) y dos densidades (266 y 400 peces/m³). Organismos de 2.1 g se alimentaron con una dieta semi-húmeda (56% Proteína y 23% Lípidos) durante 40 días en acuarios con 30 L de agua de mar. No hubo ningún efecto por la temperatura o la densidad sobre la supervivencia. El mayor crecimiento fue observado a 27°C con 400 peces/m³, mientras que los peces sometidos a 24°C y 400 peces/m³ y 30°C y 400 peces/m³ mostraron crecimientos más bajos. El porcentaje del consumo aparente de alimento diario por peso promedio del pez (%CAAD) solo fue significativamente diferente (P<0.05) entre las dos densidades de la temperatura intermedia (27°C), pero no en los grupos de la temperatura baja (24°C), ni de la alta (30°C). De manera similar al %CAAD, únicamente los valores del factor de conversión alimenticia de las dos densidades de las temperaturas de 24°C (3.8 y 2.7) y 27°C (3.4 y 2.0) fueron significativamente diferentes entre sí. Se concluye que la temperatura de 27°C y la densidad de 400 peces/m³ (equivalente a 0.84 g/L de biomasa inicial) son las condiciones más apropiadas para el crecimiento de juveniles de cabrilla arenera cultivados en laboratorio.