Influencia de la alimentación de los reproductores en la calidad de la puesta y el cultivo larvario de la dorada (Sparus aurata L.)

El rendimiento económico de la producción en acuicultura depende en gran parte del suministro de grandes cantidades de huevos de buena calidad que permitan conseguir altas tasas de supervivencia y crecimiento en el cultivo larvario. Para conseguir este objetivo es necesario disponer de un stock de reproductores suficiente en número de individuos y mantenido en las condiciones óptimas de alimentación y de control de los factores ambientales. La nutrición de los reproductores se está revelando, gracias a los estudios realizados en salmónidos, carpa, y dorada japonesa, como un factor muy importante que afecta al desarrollo gonadal y a la fecundidad. Aunque falta información precisa sobre los requerimientos nutritivos para la maduración gonadal de los reproductores, se ha comprobado, en general, que la cantidad, calidad y régimen alimentarios influyen en la cantidad y calidad de las puestas. Los estudios realizados en este campo relacionan los niveles de nutrientes en la alimentación de los reproductores con las tasas de fecundidad y fertilidad del huevo, porcentajes de eclosión, tasas de supervivencia y crecimiento de larvas, y tasas de incorporación al huevo de sustancias principalmente liposolubles. Se ha estudiado el efecto del tipo de fuente proteica y las interferencias de las proteínas con otros componentes de la dieta como minerales, micronutrientes, ácidos grasos, vitaminas y carotinoides. En los últimos años la máxima atención se ha centrado en las sustancias liposolubles; los resultados indican que los requerimientos en estas sustancias son sensiblemente diferentes en los reproductores y en las distintas etapas del cultivo. En esta línea de investigación que pretende mejorar los rendimientos de las puestas y el cultivo larvario en dorada, se llevaron a cabo en la Planta de Cultivos de Mazarrón en 1992, 1993 y 1994 tres experimentos de alimentación de reproductores centrados en la influencia de los lípidos, y especialmente los ácidos grasos, en la reproducción

The influence of organic versus conventional feeding on the growth and survival of gilthead sea bream Sparus aurata L. juveniles

Sparus aurata specimens of 11 months of age (mean weight: 90.2 g, mean length: 18.3 cm) were classified in two diet groups: one control group was fed with conventional diet, and one experimental group was fed with an organic diet. The body and muscle parameters were studied at 0, 41 and 71 days of the experiment. The results showed the highest values of body length and weight as well as the best biological feed conversion rates in the organic group. The transverse area of white muscle, the hyperplasia and the muscle fibres density were also higher in the organic than in the conventional group (P>0.05). In contrast, hypertrophy was greater in the conventional than in the organic group (P<0.05). Survival was 100% in both groups. In conclusion, the organic feeding regime was more favourable for growth than conventional feeding.Versión del edito

Effects of oral administration of 17α-ethynylestradiol on male seabream Sparus aurata L.

The effects of 17α-ethynylestradiol (EE2) on immature and mature males of the gilthead seabream (Sparus aurata L.) were studied. Gilthead seabream specimens were fed for 1 month with diets containing EE2 (5, 50, 125, 200 μg/g food). EE2 exposure altered the appetite, survival and digestive system in immature fish, and caused changes in the gonadal development, growth, survival, and some somatic indexes in mature males. The highest EE2 doses showed acute toxic effects (50% mortality) and liver injury. Gonad size was also drastically reduced

Long-term Effects of the Larval Photoperiod on the Subsequent Growth of Shi Drum Umbrina cirrosa L. Specimens and the Fillet Texture at Commercial Size

Three groups of shi drum Umbrina cirrosa L. were reared with different photoperiod regimes: 24L, 12L:12D and 16L:8D (natural photoperiod) during the larval period and then all of them were transferred to a natural photoperiod. At 11.8 and 20 months of age, the body growth and the muscle parameters reached the highest values in the 24L and 12L:12D groups. The 16L:8D group showed the lowest growth. When comparing 24L with 12L:12D, the highest number of white fibres was found in the 24L group, whereas the greatest fibres size was reached in the 12L:12D group. Commercial size (28-30 cm; 290-340 g) was reached at 20 months of age in the 24L and 12L:12D groups, but at 23 months in the 16L:8D group. When comparing the three groups at the commercial stage, the larval photoperiod effect was still observed, such that the highest fibres number was again found in the 24L group, whereas the greatest fibres size was reached in the 12L:12D group. The highest values of textural hardness were observed in the 16L:8D and 24L groups. A nutritional analysis was carried out in the 16L:8D group, which showed the following percentage values: 2.66, 21.2, 74.4, and 1.46 of fat, protein, moisture and ash, respectively.0,591

Tamoxifen disrupts the reproductive process in gilthead seabream males and modulates the effects promoted by 17alpha-ethynylestradiol

17α-ethynylestradiol (EE2), which is used in oral contraceptives and hormone replacement therapy, is a well documented estrogenic endocrine disruptor and an aquatic contaminant. In the present study, adult male specimens of the marine hermaphrodite teleost gilthead (Sparus aurata L.) were fed a diet containing tamoxifen (Tmx), an estrogen receptor ligand used in cancer therapy, alone or combined with EE2, for 25 days and then fed a commercial diet for a further 25 days (recovery period). The effects of short (5 days) and long (25 days) treatments on several reproductive and gonad immune parameters and the reversibility of the disruptive effects after the recovery period were examined. Our data showed that Tmx acted as an estrogenic endocrine disruptor as revealed by the increase in the hepatic transcription of the vitellogenin gene in males, the serum levels of 17β-estradiol and the gonad expression levels of the estrogen receptor α and G protein-coupled estrogen receptor genes, and the recruitment of leukocytes into the gonad, a well known estrogenic-dependent process in gilthead seabream males. On the other hand, Tmx also increased sperm concentration and motility as well as the serum levels of androgens and the expression levels of genes that codify for androgenic enzymes, while decreasing the expression levels of the gene that code for gonadal aromatase. When applied simultaneously, Tmx and EE2 could act in synergy or counteract, each other, depending on the parameter measured. The disruptive effect of EE2 and/or Tmx was not reversible after a 25 day recovery period.Postprin

DATOS BIOMÉTRICOS Y DE COMPOSICIÓN EN LUBINA DE TAMAÑO COMERCIAL (Dicentrarchus labrax L.) CULTIVADA A DIFERENTES TEMPERATURAS

Se estudió el crecimiento y algunos parámetros somatométricos (longitud total, a la horquilla, estándar, cefálica, y de la línea lateral; altura dorsal superior, anal, y dorsal inferior; índice de condición, cefálico, de compacidad, gonadosomático, hepatosomático, digestosomático, bazosomático, grasosomático y fracción comestible), así como la composición corporal, en lubinas de un peso de 350 g mantenidas a diferentes temperaturas desde la fertilización hasta el tamaño comercial. Los dos lotes sólo presentaron diferencias significativas en el contenido en cenizas (P0,05), que fue mayor en la población cultivada a alta temperatura. Se discutieron los resultados en relación con la temperatura. Estos resultados mostraron la escasa influencia del método de cultivo, lo que puede ser de interés por su posible efecto sobre la calidad final del producto.Biometric and composition data in sea bass, Dicentrarchus labrax (Linnaeus, 1758), of commercial size cultivated at different temperatures. Some somatometric parameters (total, fork, standard, head, and lateral line length; superior dorsal, anal, and inferior dorsal height; condition, cranial, compactness, gonadosomatic, hepatosomatic, digestosomatic, spleensoomatic, perivisceral fat and dressing index) and body composition of 350 g sea bass cultured under different temperatures from fertilization to commercial size were studied. We found significative differences (P0,05) between both groups only in ash content which was higher in the fish cultivated at high temperature. The results related to temperature are discussed. These data showed that there is no influence of culture temperature on characteristics and quality of the final product and that this fact can be of interest from the point of view of the aquaculture commercialization.CICYT. Proyecto AGL2000-1738-C03-0

Antimicrobial response is increased in the testis of European sea bass but not in gilthead seabream upon nodavirus infection

Antimicrobial peptides (AMPs) have a crucial role in the fish innate immune response, being considered a fundamental component of the first line of defence against pathogens. Moreover, AMPs have not been studied in the fish gonad since this is used by some pathogens as a vehicle or a reservoir to be transmitted to the progeny, as occurs with nodavirus (VNNV), which shows vertical transmission through the gonad, and/or gonadal fluids but no study has looked into the gonad of infected fish. In this framework, we have characterized the antimicrobial response triggered by VNNV in the testis of European sea bass, a very susceptible species of the virus, and in the gilthead seabream, which acts as a reservoir, both in vivo and in vitro, and compared with that present in the serum and brain (target tissue of VNNV). First, our data show a great antiviral response in the brain of gilthead seabream and in the gonad of European sea bass. In addition, for the first time, our results demonstrate that the antimicrobial activities (complement, lysozyme and bactericidal) and the expression of AMP genes such as complement factor 3 (c3), lysozyme (lyz), hepcidin (hamp), dicentracin (dic), piscidin (pis) or β-defensin (bdef) in the gonad of both species are very different, but generally activated in the European sea bass, probably related with the differences of susceptibility upon VNNV infection, and even differs to the brain response. Furthermore, the in vitro data suggest that some AMPs are locally regulated playing a local immune response in the gonad, while others are more dependent of the systemic immune system. Data are discussed in the light to ascertain their potential role in viral clearance by the gonad to avoid vertical transmission.Postprin