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Even though tilapia is of great economic interest, data on the nutritional requirements of amino acids during commercial breeding stages are scarce. So, the aim of this study was to analyse the performance and muscular growth of Nile tilapia larvae (Oreochromis niloticus) fed diets containing increasing concentrations of phenylalanine. The experiment took place at the Laboratory of Aquaculture of the Grupo de Estudos de Manejo na Aquicultura (GEMAq) of the Universidade Estadual do Oeste do Paraná (Unioeste), Toledo, PR, Brazil, for 30 days. A total of 450 larvae, with mean initial length of 1.5 ± 0.14 cm and mean initial weight of 0.04 ± 0.004 g, were randomly distributed into 6 treatment groups with 5 repetitions (30 tanks). Each experimental unit consisted of a 30 L tank containing 15 larvae. Six diets were formulated with increasing concentrations of phenylalanine (1.09, 1.24, 1.39, 1.54, 1.69 and 1.84%) and offered four times a day until apparent satiation. By the end of the experimental period, the following productivity indexes were analysed: length, weight, survival, weight gain, uniformity, feed conversion, specific growth rate and protein efficiency ratio. Three fish from each tank were collected for muscular growth analysis and the frequency of small (<20 µm in diameter) and large (20 -50 µm) muscle fibres recorded. Small fibres corresponded to 60% -90% of the fibres observed, suggesting that muscular growth at this stage occurred mainly by hyperplasia. No significant difference (P > 0.05) was observed in the productive performance parameters between the treatment groups. Thus, it can be concluded that the levels of phenylalanine contained in the experimental diets did not influence the performance of Nile tilapia larvae. However, there was more hyperplasia when we put 1.39% of phenylalanine in the diet.How to cite this paper:

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ABSTRACT. This work evaluated five classes of weight of bullfrog (Lithobates catesbeianus) seeking to define the ideal slaughter weight for the species. We used 79 bullfrogs, distributed in a completely randomized design (class 1 < 100 g (n = 10); class 2 from 101 to 150 g (n = 17); class 3 from 151 to 200 g (n = 24); class 4 from 201 to 250 g (n = 14); and class 5 >251 g (n = 14)), which were euthanized, weighted and gutted. For the carcass yield, we weighed the clean torso, thighs, liver, skin and head. The clean torso was subjected to chemical composition analysis. The carcass yield was, on average, 49% with no difference between weight classes (p > 0.05). The yield of posterior thighs was significantly higher for the lower weight class, which also presented higher percentage of paws (28.37 ± 0.63 and 9.33 ± 0.21, respectively) (p < 0.05). The percentages of visceral fat and skin showed a progressive increase along with the weight of the animals; the class with individuals weighing 201-250 grams showed the higher values (p < 0.05). The chemical composition indicated that individuals above 251 grams showed lower values of ether extract and higher values of crude protein (0.99 ± 0.14 and 15.80 ± 0.64, respectively) (p < 0.05). So, it is recommended the slaughter of bullfrogs weighing more than 201 grams, because of better yield and meat quality.Keywords: exotic species, meat processing, raniculture. Rendimento de carcaça e composição centesimal da rã-touro (Lithobates catesbeianus)RESUMO. O objetivo do trabalho foi comparar cinco diferentes classes de peso de rã-touro (Lithobates catesbeianus), buscando definir o peso ideal de abate para a espécie. Foram utilizados 79 exemplares de rãs-touro, distribuídas em um delineamento inteiramente casualizado (classe 1 <100 g (n = 10); classe 2 de 101 a 150 g (n = 17); classe 3 de 151 a 200 g (n = 24); classe 4 de 200 a 250 g (n = 14), e classe 5 > 251 g (n = 14)), que foram eutanaziados, pesados e eviscerados. Para o rendimento da carcaça foram pesados: tronco limpo, coxas, fígado, patas, pele e cabeça. O tronco limpo foi submetido à análise de composição centesimal. O rendimento de corpo limpo foi em média 49%, sem diferença entre classes (p > 0,05). O rendimento das coxas posteriores foi significativamente maior para a menor classe de peso, e essa classe também apresentou maior porcentual de patas (28,37 ± 0,63 e 9,33 ± 0,21, respectivamente) (p < 0,05). As porcentagens de gordura visceral e pele apresentaram um aumento progressivo concomitante ao peso dos animais, sendo que a classe com indivíduos de 201 a 250 g apresentou os maiores índices (p < 0,05). Na composição centesimal observou-se que indivíduos acima de 251 g, apresentaram menores valores de extrato etéreo e maior valor de proteína (0,99 ± 0,14 e 15,80 ± 0,64, respectivamente) (p < 0,05). Para melhor aproveitamento é recomendado que rãs-touro sejam abatidas com peso superior a 201 g, pois apresentam melhores rendimentos e características da carne.Palavras chave: espécie exótica, processamento de carne, ranic...

This study aimed at evaluating the effects of a probiotic additive in productive performance and physiological parameters for Rhamdia quelen. The fish were fed diets containing increasing levels of the additive (0.15; 0.30; 0.45; and 0.60 g/kg of feed), which consisted of a blend of Bacillus cereus and B. subtilis, both at the concentration of 4 × 10 11 CFU). Productive performance parameters were higher in fish fed diets containing 0.60 g/kg of the probiotics. Both the proximate composition and carcass yield were affected when 0.30 and 0.60 g/kg of the additive was included, whilst serum biochemical parameters were higher in fish fed diets containing 0.60 g/kg of the additive. An increase in the hepatic oxidative stress activity was found when 0.30 g/kg was supplied. The development of intestinal villi was influenced by the inclusion of the additives, as well as the activity of mucous-secreting cells in the tissue. Hepatocyte's growth was differential in fish fed diets containing 0.30 g/kg and other tissue alterations were found using 0.60 g/kg of the additive. The inclusion of 0.60 g/kg of the probiotic in diets for R. quelen enhances its growth performance and physiological status. K E Y W O R D S biotechnology, fish farming, immunomodulatory, native species, non-pathogenic bacteria | 455 LINS-RODIGUES Et aL. by improving the activity of digestive enzymes, besides boosting the animals' immune system (Azevedo et al., 2016; Nakandakare et al., 2013; Wild et al., 2014). In addition, B. subtilis has known bactericidal and fungicidal effects, as it may increase the immune responses of the host (Ramesh & Souissi, 2017). The silver catfish (Rhamdia quelen) became one of the most studied native species by presenting expressive growth, excellent feed conversion, tolerance to handling, high carcass yield and reproductive viability when reared in captivity (Amaral-Junior et al., 2008; Barcellos et al., 2004; Carneiro et al., 2006). In addition, its high acceptance in the consumers market has increasing the number of rearing facilities, which can be performed either in excavated ponds or net-cages, from the initial stages to termination, presenting optimal growth throughout all year, even during periods of low tem

Fenilalanina em dietas para juvenis de tilápia do niloPhenylalanine in diets for juvenile of nile tilapia

O objetivo deste estudo foi avaliar o desempenho produtivo, histomorfometria intestinal e composição corporal de juvenis de jundiá alimentados com dietas contendo níveis crescentes de inclusão (0, 25, 50, 75 e 100%) de farelo de canola (FC) em substituição ao farelo de soja (FS), suplementadas ou não com a enzima fitase (0 e 1500 UFA/kg-1). Grupos de 10 peixes foram distribuídos aleatoriamente em 30 unidades experimentais e alimentados com suas respectivas dietas experimentais por 60 dias. Houve interação significativa entre os fatores para o ganho em peso (GP), conversão alimentar aparente (CAA) e taxa de eficiência proteica (TEP). Para o GP, os maiores resultados foram evidenciados nos jundiás alimentados com dietas contendo 100% de FC, sem fitase, e 75% de FC, com fitase. Na CAA, os melhores resultados foram verificados nos peixes alimentados com 50, 75 e 100% de inclusão de FC, independente da suplementação da enzima. A TEP foi maior nos peixes alimentados com 50% de FC, sem fitase. Houve influência da substituição de FS por FC para a taxa de crescimento específico (TCE), altura das dobras intestinais e matéria mineral corporal (MM). A maior TCE foi verificada nos peixes alimentados com 100% de substituição. A maior altura das dobras intestinais foi observada nos peixes alimentados com 75% de FC na dieta e a maior MM foi verificada nos peixes alimentados com dietas sem a inclusão de FC. O FC pode substituir o FS em dietas para juvenis de jundiá, contudo, sugerimos novos estudos para compreender a utilização combinada de fitase e FC em dietas para esta espécie.