The effects of different combinations of epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) on cumulus expansion and meiotic maturation were examined in rabbit oocytes. Selected rabbit follicular oocytes were matured in vitro and were classified as cumulus-oocyte complexes or denuded oocytes. They were cultured in TCM 199, and were treated with growth factors at different concentrations: EGF at 0, 1, 10, 50 and 100 ng ml-1, IGF-I at 0, 50, 100 and 200 ng ml-1 and EGF plus IGF-I at 10 + 50; 10 + 100; 50 + 50 and 50 + 100 ng ml-1, respectively. After 6 h of culture, the oocytes were assessed for nuclear maturation and after 16 h of culture, for cumulus expansion and maturation stage. After culture for 6 h, the incidence of germinal vesicle breakdown was higher (P < 0.05) in all of the growth factor treatments tested compared with controls. After culture for 16 h, EGF enhanced the incidence of cumulus expansion at all of the concentrations tested. Cumulus expansion was greatest with 50 mg EGF ml-1 plus 100 ng IGF-I ml-1 (72.0% versus 2.4% in controls). Treatment with IGF-I significantly increased (P < 0.05) the incidence of metaphase II stage, and maximum stimulation occurred at 100 ng IGF-I ml-1 (84.5% versus 31.1% in controls). However, IGF-I did not affect cumulus expansion. When denuded oocytes were used, no positive effects on nuclear maturation rates were observed for any treatment. These results suggest that: (1) EGF, either alone or with IGF-I, stimulates cumulus expansion; (2) the addition of IGF-I or EGF plus IGF-I significantly enhances nuclear maturation in immature rabbit oocytes; and (3) this effect is mediated by the presence of cumulus cells.

Aquaponics is the science of integrating intensive fish aquaculture with plant production in recirculating water systems. Although ion waste production by f ish cannot satisfy all plant requirements, less is known about the relationship between total feed provided for f ish and the production of milliequivalents (mEq) of different macronutrients for plants, especially for nutrient flow hydroponics used for strawberry production in Spain. That knowledge is essential to consider the amount of macronutrients available in aquaculture systems so that farmers can estimate how much nutrient needs to be supplemented in the waste water from fish, to produce viable plant growth. In the present experiment, tilapia (Oreochromis niloticus L.) were grown in a small-scale recirculating system at two different densities while growth and feed consumption were noted every week for five weeks. At the same time points, water samples were taken to measure pH, EC 25 , suggesting that it would be rather easy to maintain small populations of fish to reduce the cost of hydroponic solution supplementation for strawberries.Additional key words: aquaculture; nutrients; recirculating system; tilapia; water quality. ResumenAquaponica: integrando la tasa de alimentación de peces y la producción de iones residuales para la hidroponía de fresas La aquaponía es la ciencia de integrar la acuicultura intensiva con la producción de plantas en sistemas con agua en recirculación. A pesar de que se ha encontrado que la producción de iones residuales de los peces no llega a satisfacer todos lo requisitos de las plantas, se sabe menos sobre la relación entre el pienso total dispensado para los peces y la producción en milliequivalentes (mEq) de los diferentes macronutrientes para plantas, especialmente para hidroponía recirculante usada para la producción de fresas en España. Es esencial tener este conocimiento para calcular la cantidad de macronutrients disponibles en sistemas de acuicultura para que los agricultores puedan estimar la cantidad de nutrientes que hay añadir al agua residual de los peces, para un crecimiento viable de plantas. En este experimento, se alimentó a tilapia (Oreochromis niloticus L.) en un sistema de recirculación a pequeña escala a dos densidades diferentes, controlando el crecimiento de los peces y el pienso consumido una vez cada semana durante cinco semanas. A la vez, se tomó muestras de agua para medir el pH, CE 25 2-. La cantidad total de pienso requerido por mEq varió entre 1 y 13 kg, lo cual sugiere que sería relativamente sencillo mantener poblaciones pequeñas de peces para reducir el coste de la solución fertilizante para las fresas.

The study is an attempt to evaluate the feasibility of intensive tench culture using non-specific diets as a preliminary step to check the acclimatization of the species under intensive rearing systems. Five-month-old juvenile tench were reared in recirculating systems at mean water temperatures of 22°C for 75 days. Fish fed with four different commercial diets (trout starter, trout first feeding, sea-bass and eel), showed significantly higher final weights than the fish fed either eel or sea-bass diets. Initial weight for all treatments was 2.3 ± 0.53 g. Final weight for the commercial diet groups was 3.56 ± 0.4 g, compared with the remaining groups that reached 2.09 ± 0.47 g (P < 0.05). Significantly higher survival rates were observed in the eel and sea-bass groups (84.7 and 51.5%, respectively) than in either of the trout diet groups (38%). Specific growth rates (1.26 vs -0.18) and condition factor (1.26 vs 0.93) were also higher than those fed with salmonid diets (P < 0.05). Results obtained in this study indicate that regardless of the speciesÕ slow growth, when compared with other cyprinids, final growth rates and survival of tench fed exclusively on sea-bass or eel diets can be considered satisfactory. It must be pointed out that these promising results were obtained at lower temperatures than previous studies of tench in culture systems. The use of belt feeders did not show improvement in growth compared with manually fed fish when trout diets were used.

No abstract

The cyclic pattern of oocyte development in the sea bass, Dicenrrurchus lubrux L., was studied after induction of spawning by two injections. 24 h apart, of a luteinizing hormone releasinghormone analog (LHRHa) administered at the end of vitellogenesis. The first difference in the developmental stage of the ovary and in the sizefrequency distribution of oocytes between the LHRHa treated group and the control group, was detected 32 h after the first injection, the LHRHa group showing a higher proportion of the 900 pm diameter oocyte class (maturing oocytes) (P <0,01). At 48 h LHRHa-treated females showed an increase in the 1000 and 1100 pm classes (maturing oocyte and ovulated eggs) (P