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In order to explore the effects of vacuum heat treatment and gluten on the gel properties of myofibrillar protein (MP), the effects of vacuum heat treatment and gluten addition on tilapia MP gel were studied by testing texture, water retention, intermolecular forces and other indicators. Under the condition of water bath, the addition of 0.7% gluten significantly improved the hardness and gel strength of MP. The microstructure results showed that the gluten made the MP gel network tend to be flat and the holes decreased, which was conducive to the formation of gel. Compared with the water bath heating, the cohesion, elasticity and gel strength of MP gel were significantly improved after 1 h of one-stage vacuum heat treatment. After 2 h of vacuum heat treatment, the cohesion and gel strength of MP gel were further improved. In addition, vacuum heat treatment and gluten addition improved the moisture state of MP gel, the content of T22 fixed water decreased, and the migration of T22 fixed water and T23 free water was restricted, resulting in the stability of the moisture in the gel. The results of intermolecular forces showed that the interaction between ionic bond and hydrophobic interaction was enhanced, which promoted the gelation of MP. In summary, vacuum processing promotes the structure extension of MP and the formation of a more compact three-dimensional gel network.

Antecedentes: Algunos aditivos alimentarios se han vuelto en la actualidad alternativas a discrepancias tales como la búsqueda de mejores rendimientos manteniéndose dentro de los márgenes productivamente sustentables, orgánicos y ecológicos. De esta manera se incorporan nutrientes y microorganismos a la dieta como una forma alternativa de mejorar la inmunidad de los peces, aprovechando los nutrientes en el alimento y actuando positivamente en el desempeño de los animales. El objetivo del presente trabajo fue recopilar información referente al uso de aditivos inmunoestimulantes en Tilapias (Oreochromis ssp.) y su desempeño fisiológico en el organismo. Desarrollo: Muchos de estos inmunoestimulantes existentes son microorganismos o nutrientes habituales de la dieta como son los polisacáridos, proteínas o lípidos, que suministrados en concentraciones elevadas tienen la capacidad producir un efecto estimulante acelerando la resistencia a las enfermedades mediante mecanismos específicos o inespecíficos de la respuesta inmunológica, convirtiéndose en agentes primarios profilácticos. Conclusiones: El empleo de aditivos inmunoestimulantes posibilita la prevención de enfermedades comunes en el cultivo de tilapias por medio de la modulación del ambiente intestinal en las diferentes especies del género Oreochromis mejorando la respuesta inmune inespecífica y a su vez se favorecen algunos procesos tales como el crecimiento individual, la eficiencia alimenticia y la tolerancia al estrés.

Background: Some diet additives have become alternatives to achieve higher yields within the productively sustainable, organic, and ecological margins. Hence, nutrients and microorganisms can be added to the diet for fish immunity improvements, by using the nutrients in the feed, which lead to a positive animal performance. Accordingly, the aim of this paper was to gather information related to the utilization of additives as immunostimulant in tilapia (Oreochromis ssp.), and their physiological performance in the body. Development: Many of these immunostimulants are microorganisms or habitual nutrients in the diet, such as polysaccharides, proteins or lipids, which at high concentrations are capable of creating a stimulating effect, speeding disease resistance through specific or unspecific mechanisms of immunological response, thus becoming primary prophylactic agents. Conclusions: The use of additives as immunostimulants helps prevent the occurrence of common diseases in tilapia culture, by modulating the intestinal system in the different species of genus Oreochromis, thus enhancing the unspecific immune response, and, in turn, some processes like individual growth, feeding efficiency, and stress tolerance can be favored. [ABSTRACT FROM AUTHOR]

Reproduction involves multiple complex behaviours, and the effects of familiarity on such social interactions are seldom described in fish. This is particularly true for sound production and communication within aggressive or non-aggressive context. This study explores the effects of a common garden rearing without parental care of two closely related cichlid species (Nile tilapia Oreochromis niloticus and blackchinned tilapia Sarotherodon melanotheron) on their sound production features and social interactions. After 9 months in common garden rearing, from embryonic stage to first maturity, sound production and associated behaviours were recorded on specimens of the two species in intraspecific and interspecific pairings. The authors found that fish were able to produce the same kind of sounds as those recorded in similar context for their parents. Drum sounds were associated to chasing, lateral attack and courtship in O. niloticus and only to fleeing or avoidance in S. melanotheron. Specific grunts were produced in chasing, after biting and in nest building by O. niloticus, and specific rolling sounds were associated to courtship in S. melanotheron. Sound production and behaviours were not correlated to sex steroid levels, but the number of sounds recorded in aggressive context was correlated to dominance in O. niloticus. The authors conclude that one generation of common garden rearing does not modify sound features, which remain specific and innate in the two cichlids. Despite the familiarity, O. niloticus remained dominant on S. melanotheron, but the aggressiveness between the two species decreased. [ABSTRACT FROM AUTHOR]

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Copyright of Acta Veterinaria Brasilica is the property of Acta Veterinaria Brasilica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)