First record of the nematode Echinocephalus pseudouncinatus (Gnathostomatidae, Spirurida) in an edible, commercial host, the pen shell Atrina maura (Bivalvia: Pinnidae).

We describe a nematode infestation of the Atrina maura, the most valuable pen shell fished in Mexico, for the first time. Observations by Mexican authorities indicated that parasites were found encysted in pen shell gonads. The aims of this study included: (i) to identify the parasite morphologically; (ii) to quantify the infestation in different tissues of the pen shell; and (iii) to establish the seasonal variation in gonadal development. During 2015, 10 to 40 pen shells were randomly collected each month from the same commercial bed, and gonads were preserved and processed histologically to establish the seasonal and monthly frequency of infested gonads. A subsample of 35 pen shells was used to identify the parasite and to characterize the infestation of the muscle, mantle, gonad, and digestive gland tissue components. All tissues were dissected, and parasites were collected, photographed, quantified, and adequately preserved for species identification using scanning electron microscopy. Prevalence, intensity of infestation, abundance and crowding data were analyzed by Quantitative Parasitology software and compared monthly and seasonally using a chi test and analysis of means. Results indicated that all parasites were juvenile (second stage) nematodes, Echinocephalus pseudouncinatus. Parasites were found only in muscle and gonad tissues in both male and female pen shells. Hyperpigmentation was observed in the muscle and atretic oocytes with phagocytosis in the gonads. The frequency of infested gonads was significantly higher during winter but was not related to shell size or sex (p > 0.05). A greater number of pen shells were observed to be infested during December and August and during pen shell spawning and development stages. The highest frequency of infested gonads (40%) occurred in December when the lowest temperature and chlorophyll a concentration were recorded. The effects of the biotic and abiotic parameters on this host-pathogen relationship need further research. This nematode species is related to species that are causal agents of gnathostomiasis, which may constitute a health hazard for raw muscle consumers and could affect the reproductive activity of pen shell.

Evaluación del crecimiento de un cultivo de Daphnia magnaalimentado con Saccharomyces cereviseae y unenriquecimiento con avena soya / Avaliação do crescimento de um cultivo de Daphnia magna alimentada conSaccharomyces cereviseae e um meio enrriquecido com aveia soja / Growth culture evaluation of Daphnia magna feed with Saccharomyces cereviseae enrichment with oat soy

Se realizó el cultivo experimental de cladócero Daphnia magna alimentado con probióticos. Serealizaron 16 ensayos experimentales, en el laboratorio de larvicultura de peces y alimento vivo (Larpeali)de la Facultad de Ciencias Agrarias de la Universidad de Antioquia, bajo condiciones controladas detemperatura ambiente (21 - 25 °C), temperatura del agua (22 - 23 °C) y pH (7.6). Empleando una dietade Saccharomyces cereviseae y un medio de enriquecimiento con ácidos grasos (n-6) proveniente deharina avena-soya. Las concentraciones de dieta y enriquecimiento fueron de 25 ppm y 12.5 ppm, enarreglo factorial 2x2 (2 niveles de dieta con levadura y 2 niveles dieta con avena de soya), los cultivosde Daphnia por tratamiento se realizaron con cuatro replicas con el fin de determinar su efecto sobreel desempeño de la población. Se alimentaron cada tercer día, durante 15 días, evaluándose el númerode organismos al final del período. Se obtuvieron diferencias altamente significativas (p<0.01) para elefecto del tratamiento con una concentración de 25 ppm Saccharomyces cereviseae + harina de avenasoyaa una concentración de 25 ppm. De igual forma se observó una diferencia significativa (p<0.05) en el tratamiento con Saccharomyces cereviseae a 12.5 ppm + harina de avena-soya 25 ppm sobre elcrecimiento poblacional de los cladóceros. En el resto de los tratamientos no se observaron diferenciassignificativas (p>0.05). Se evidenció que la combinación de estos componentes en sus concentracionesmás altas potenció el crecimiento de la Daphnia magna, alcanzando un número de microcrustáceos de826ª Daphnias/L ± 9.57. Se puede concluir que los cladóceros por sus características de crecimiento encultivo, presentan adaptación favorable a las condiciones de manejo para la producción de biomasa útilcomo alimento vivo en acuicultura.

Experimental cultivate cladocerans Daphnia magna feed with probiotics was realized. At Universityof Antioquia, Faculty of Agrarian Science, Larviculture, fish and food live Laboratory (Larpeali), undercontrolled conditions of environmental temperature between (21 - 25 °C), water temperature (22 - 23°C)and pH (7.6), were performed. One diet of Saccharomyces cereviseae was used and one enriched mediumof oat-soy flour (fatty acid, n-6) to concentrations of diet and enriched medium were the same, 25 ppmand 12.5 ppm, 2x2 factorial treatment arrangements (2 levels of Saccharomyces cereviseae and 2 levelsof oat-soy flour, diets was fed to four replicates of Daphnia culture per treatment in order to determinetheir effects on the populations cultivated. A 15-days feeding, each third day, trial were conducted, to assessthe organisms at final period. The results showed significant high difference (p<0.01) for the effect of thetreatment with Saccharomyces cereviseae 25 ppm + oat-soy flour 25 ppm. In the same way, the results showedsignificant difference (p<0.05) for the effect of the treatment with Saccharomyces cereviseae 12.5 ppm +oat-soy flour 25 ppm on the population growth of the cladocerans. Rest of treatments were not significantlydifference (p>0.05). The results showed that the combination of their high concentrations of componentsenhanced the population growth of Daphnia magna, reaching a number of microcrustaceans of 826ª ± 9.57.These cladocerans for their characteristics of growth in culture, present favorable adaptation to the handlingconditions to produce biomasses potentially useful as nutritious particle as live food in aquaculture purposes.

O objetivo do experimento foi avaliar o efeito das gorduras saturadas e insaturadas e seu grau deproteção (protegidas e sem proteção) sob a cinética e a extensão da degradação in vitro da matéria seca(MS) em dietas para ruminantes. Quatro dietas foram formuladas para conter o mesmo nível de energia(3200 Kcal ED /Kg MS) e proteína (13%PC) a ração total misturada (RTM), de acordo com as necessidadesnutricionais de ovelhas em fase de finalização, quatro tipos de gorduras foram feitas com 8% de MS eforam testados tipos de gorduras foram testados: 1) gordura saturada sem proteção (GSSP), 2) gordurasaturada protegida (GSP), 3) gordura insaturada sem proteção (GISP) e 4) gordura insaturada protegida(GIP). Para estimar a cinética e a extensão da degradação da MS e cinética da produção de gás, as raçõesforam avaliadas mediante a técnica in vitro de produção de gás, seguindo os modelos propostos por Orskove McDonald (1979) y France et al (1993), para isto foi empregado o procedimento PROC NLIN de SAS(2001). Ao mesmo tempo, foi realizado um analise de medidas repetidas no tempo para verificar o efeito dostratamentos sobre a produção de gás e a degradação da MS no tempo com ajuda do procedimento PROCMIXED do SAS (2001.) Neste experimento verificou-se que a utilização de gorduras insaturadas protegidasnão afetou a degradação de MS quando comparadas com as não protegidas. No caso das gorduras saturadas,não houve um claro efeito da proteção sob a degradação e a cinética de fermentação da MS.