Caracterização do surimi de tilápia do Nilo: morfologia e propiedades físicas, químicas e sensoriais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Elaboração de produto cárneo de tilápia com antioxidantes visando sua utilização como recheio ou acompanhamento de refeição

The aim of this study is to evaluate the effi ciency of oregano, sage, moringa and rosemary as natural antioxidants and propyl gallate as artifi cial antioxidant used in “stuffed food” made with CMS of tilapia (minced fi sh) and stored frozen for 120 days. Protein, fat, moisture and ashes determination, microbiological analysis and sensory evaluations were conducted in the beginning and the end of storage period. TBARS, BNVT, pH and psychrotrophic microorganism count were determined periodically. The antioxidants interfered in pH (6.17 and 6.55) and TBARS values during 120 days under freezing (-18o C). The lowest TBA values were found for oregano (0.158 mg de MDA. kg-1) and sage (0.186 mg de MDA.kg-1). The stuffed food made with CMS of tilapia, without antioxidant, had the most oxidation, and sage and moringa were not good source of antioxidant. BNVT values (11.41 – 12.35 mgN.100g-1) were not altered. The lowest pH value was found for the product with sage (6.20), but similar to the moringa and propyl gallate, while oregano and rosemary showed the highest values (6.63 and 6.29), at 5 days of storage. Microbiological analyses were in accordance with Brazilian legislation. Sensory evaluation indicated that the panelists preferred the formulations made with oregano and propyl gallate. The results showed that it is feasible to elaborate stuffed food made with CMS of tilapia as an alternative for the fi shery´s consumption, and sage was the most effi cient natural antioxidant among those tested in this study.

Elaboration of sausage using minced fish of Nile tilapia filleting waste

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Elaboration of sausage using minced fish of Nile tilapia filleting waste

O objetivo deste estudo foi avaliar a inclusão de carne mecanicamente separada (CMS) (0, 20, 40, 60, 80 e 100%), obtido de resíduos de filetagem de tilápias do Nilo, em salsichas e determinar suas propriedades físico-químicas, nutricionais e sensoriais. As salsichas apresentaram diminuição de proteína e aumento de lipídeos com a inclusão de CMS. A qualidade nutricional dos produtos foi alta, com digestibilidade acima de 85%. Os parâmetros de textura e cor instrumental amarela (b*) diminuíram com inclusão crescente de CMS. A avaliação sensorial da cor mostrou que o nível máximo de inclusão de CMS não foi bem aceito pelos provadores. As salsichas com melhor aceitação do atributo sabor foram aquelas com 60% de CMS. Os resultados demonstraram a boa qualidade nutricional das salsichas utilizando CMS de resíduos de filetagem de tilápias do Nilo e de acordo com avaliação sensorial, a porcentagem máxima de inclusão é de 60%.

Characterization and evaluation of the impact of feed management on the effluents of Nile tilapia (Oreochromis niloticus) culture

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Nile tilapia, Oreochromis niloticus, productive performance and carcass characteristics as related to food management

Male juveniles of Nile tilapia, Oreochromis niloticus, were stocked in 12, 300-m 2 ponds at a density of 1.7 fish/m 2 to evaluate the effects of different food management methods (natural foods and diets in pellet, floating or minced form) on fish production and carcass characteristics. Water quality variables monitored during the period were within acceptable levels for the species. Total fish production was significantly different (P < 0.05) and the highest values were obtained with diets in pellet (5,997 kg/ha) and floating (5,441 kg/ha) form. The fish fed diets had higher contents of body fat (1.57 to 1.98%) and visceral fat (12.64 to 25.04%) than fish fed natural food, which had levels between 0.17 and 0%, respectively. Natural food treatment yielded lower fish production and fish with lower body fat, while treatments that yielded higher fish production (rations) higher percentage of visceral fat. © 2004 by The Haworth Press, Inc. All rights reserved.

Characterization and evaluation of the impact of feed management on the effluents of Nile tilapia (Oreochromis niloticus) culture

O objetivo deste trabalho foi avaliar o efeito da utilização de diferentes manejos alimentares: alimento natural, ração peletizada, extrusada ou farelada, sobre a qualidade da água dos efluentes gerados em uma criação de tilápia do Nilo (Oreochromis niloticus). O experimento foi desenvolvido durante 19 semanas em doze viveiros de 300 m², com renovação contínua de água, povoados com juvenis machos de tilápia do Nilo na densidade de 1,7 peixes m-2. As rações isoproteícas (30% de proteína bruta) e isoenergéticas (3.000kcal de energia digestível) foram fornecidas duas vezes ao dia. Quanto ao tratamento alimento natural, foi utilizado esterco de galinha poedeira. Semanalmente, foram aferidos na água de abastecimento e nos efluentes, temperatura, oxigênio dissolvido, pH, fósforo total, nitrogênio total, clorofila a e material em suspensão. de maneira geral, houve piora na qualidade da água dos efluentes de todos os tratamentos estudados, em comparação a água de abastecimento, evidenciando o impacto ambiental desta atividade produtiva, podendo levar a eutrofização dos corpos d'água receptores.

Regulation of Gonadotropin-Releasing Hormone (GnRH)-Receptor Gene Expression in Tilapia: Effect of GnRH and Dopamine

The present work was designed to study certain aspects of the endocrine regulation of gonadotropin-releasing hormone receptor (GnRH-R) in the pituitary of the teleost fish tilapia. A GnRH-R was cloned from the pituitary of hybrid tilapia (taGnRH-R) and was identified as a typical seven-transmembrane receptor. Northern blot analysis revealed a single GnRH-R transcript in the pituitary of approximately 2.3 kilobases. The taGnRH-R mRNA levels were significantly higher in females than in males. Injection of the salmon GnRH analog (sGnRHa; 5–50 μg/kg) increased the steady-state levels of taGnRH-R mRNA, with the highest response recorded at 25 μg/kg and at 36 h. At the higher dose of sGnRHa (50 μg/kg), taGnRH-R transcript appeared to be down-regulated. Exposure of tilapia pituitary cells in culture to graded doses (0.1–100 nM) of seabream (sbGnRH = GnRH I), chicken II (cGnRH II), or salmon GnRH (sGnRH = GnRH III) resulted in a significant increase in taGnRH-R mRNA levels. The highest levels of both LH release and taGnRH-R mRNA levels were recorded after exposure to cGnRH II and the lowest after exposure to sbGnRH. The dopamine-agonist quinpirole suppressed LH release and mRNA levels of taGnRH-R, indicating an inhibitory effect on GnRH-R synthesis. Collectively, these data provide evidence that GnRH in tilapia can up- regulate, whereas dopamine down-regulates, taGnRH-R mRNA levels.

An evaluation of electrofishing as a control measure for an invasive tilapia (Oreochromis mossambicus) population in northern Australia.

Combating the spread of invasive fish is problematic, with eradication rarely possible and control options varying enormously in their effectiveness. In two small impoundments in north-eastern Australia, an electrofishing removal program was conducted to control an invasive tilapia population. We hypothesised that electrofishing would reduce the population density of Oreochromis mossambicus (Mozambique tilapia), to limit the risk of downstream spread into areas of high conservation value. We sampled by electrofishing monthly for 33 months. Over this period, there was an 87% decline in catch per unit effort (CPUE) of mature fish, coupled with a corresponding increase of 366% in the number of juveniles, suggesting a density-dependent response in the stock-recruitment relationship for the population. Temperature was inversely related to CPUE (r=0.43, lag=10 days), implying greater electrofishing efficiency in cooler months. The reduction in breeding stock is likely to reduce the risk of spread and render the population vulnerable to other control measures such as netting and/or biological control. Importantly, the current study suggests routine electrofishing may be a useful control tool for invasive fish in small impoundments when the use of more destructive techniques, such as piscicides, is untenable.

Tilapia in Australia – Development of management strategies for the control and eradication of feral tilapia populations in Australia

This report presents a culmination of different research projects on two species of tilapia (Oreochromis mossambicus and Tilapia mariae) and provides recommendations for the future management and research of these pest fish. Feral populations of O. mossambicus and T. mariae are now widely distributed in tropical northeastern Queensland, with O. mossambicus also occurring in southeastern Queensland and river systems of Western Australia. O. mossambicus is known to have existed in impoundments in southeastern Queensland, as well as urban drains and ornamental ponds in the Townsville region of north Queensland from about the late 1970s, while T. mariae became established in some easternflowing tropical streams by the early 1990s. In Australia, feral stocks of tilapia are widely regarded as pests that potentially threaten both native fish stocks and biodiversity.

Reproductive strategies of two invasive tilapia species Oreochromis mossambicus and Tilapia mariae in northern Australia

The reproductive biology of two invasive tilapia species, Oreochromis mossambicus and Tilapia mariae, resident in freshwater habitats in north-eastern Australia was investigated. Oreochromis mossambicus exhibited plasticity in some of its life-history characteristics that enhanced its ability to occupy a range of habitats. These included a shallow, weed-choked, freshwater coastal drain that was subject to temperature and dissolved oxygen extremes and water-level fluctuations to cooler, relatively high-altitude impoundments. Adaptations to harsher conditions included a decreased total length (LT) and age ( A) at 50% maturity (m50), short somatic growth intervals, early maturation and higher relative fecundities. Potential fecundity in both species was relatively low, but parental care ensured high survival rates of both eggs and larvae. No significant difference in the relative fecundity of T. mariae populations in a large impoundment and a coastal river was found, but there were significant differences in relative fecundities between several of the O. mossambicus populations sampled. Total length ( LT) and age at 50% maturity of O. mossambicus populations varied considerably depending on habitat. The LTm50 and Am50 values for male and female O. mossambicus in a large impoundment were considerably greater than for those resident in a small coastal drain. Monthly gonad developmental stages and gonado-somatic indices suggested that in coastal areas, spawning of O. mossambicus and T. mariae occurred throughout most of the year while in cooler, high-altitude impoundments, spawning peaked in the warmer, summer months. The contribution these reproductive characteristics make to the success of both species as colonizers is discussed in the context of future control and management options for tilapia incursions in Australia.

A review of the biology, ecology, distribution and control of Mozambique tilapia, Oreochromis mossambicus (Peters 1852) (Pisces: Cichlidae) with particular emphasis on invasive Australian populations

Oreochromis mossambicus (Peters 1852) are native to the eastward flowing rivers of central and southern Africa but from the early 1930s they have been widely distributed around the world for aquaculture and for biological control of weeds and insects. While O. mossambicus are now not commonly used as an aquaculture species, the biological traits that made them a popular culture species including tolerance to wide ranging ecological conditions, generalist dietary requirements and rapid reproduction with maternal care have also made them a 'model' invader. Self-sustaining populations now exist in almost every region to which they have been imported. In Australia, since their introduction in the 1970s, O. mossambicus have become established in catchments along the east and west coasts and have the potential to colonise other adjacent drainages. It is thought that intentional translocations are likely to be the most significant factor in their spread in Australia. The ecological and physical tolerances and preferences, reproductive behaviour, hybridization and the high degree of plasticity in the life history traits of O. mossambicus are reviewed. Impacts of O. mossambicus on natural ecosystems including competitive displacement of native species, habitat alteration, predation and as a vector in the spread of diseases are discussed. Potential methods for eradicating or controlling invasive populations of O. mossambicus including physical removal, piscicides, screens, environmental management and genetic technologies are outlined.

Fish Silage as Replacement of Fishmeal in Red Tilapia Feeds

We estimated the effect on growth and nutrient efficiency of replacing fishmeal with silage incorporated with rice bran in diets for fingerling red tilapia (Oreochromis mossambicus × Oreochromis niloticus × Oreochromis aureus) over 12 weeks. Isonitrogenous (300 g kg−1 protein dry matter basis) and isoenergetic (4450 Kcal gross energy kg−1) feed formulations with increasing levels of tilapia silage as a replacement for fishmeal were prepared: Diet 1 with no silage (0 g Kg−1), Diet 2 (250 g Kg−1), Diet 3 (500 g Kg−1), and Diet 4 (750 g Kg−1). Feed intake was similar among Diets 1, 2, and 3, while Diet 4 had a significantly lower intake. There was no significant difference (P > 0.05) in weight gain or specific growth rate (SGR), feed conversion ratio (FCR), and protein efficiency ratio (PER), among fish fed Diets 1, 2, and 3. Fish fed with Diet 4 had significantly lower weight gain; SGR and PER and significantly higher FCR. Organoleptic properties of the fish were not affected by the diets. The results of this study indicate that less expensive dried fish silage with rice bran is an alternative protein source for tilapia feed up to 50% of fishmeal replacement.