Glúten de trigo em dietas para tilápia do Nilo: digestibilidade e desempenho produtivo de larvas / Wheat gluten in the diet of Nile tilapia: digestibility and larvae growth performance

O objetivo do presente trabalho foi avaliar o potencial de utilização do glúten de trigo em dietas para tilápia-do-nilo (Orechromis niloticus), através de estudos de digestibilidade e desempenho produtivo de larvas. Para o estudo de digestibilidade foi elaborada uma dieta referência e uma dieta teste, contendo glúten de trigo. Utilizou-se o óxido de crômio III como marcador inerte. As fezes coletadas foram destinadas à análise de composição química, assim como as rações e o ingrediente teste. Além disso, foi realizada análise de leitura de óxido de crômio das fezes e das dietas. Os resultados obtidos por meio dessas análises foram utilizados para calcular os coeficientes de digestibilidade. Com base nesses coeficientes foram elaboradas as dietas experimentais dos estudos de dose-resposta para larvas. Foram formuladas cinco dietas experimentais com diferentes níveis de inclusão de glúten de trigo, sendo de 0%; 2,5%; 5,0%, 7,5% e 10%. Ao final do experimento foram avaliados o desempenho produtivo dos animais. Os dados de desempenho foram submetidos à análise de regressão linear a 5% de probabilidade. O glúten de trigo apresenta elevados coeficientes de digestibilidade para matéria seca, proteína bruta e energia bruta, sendo de 94,02; 98,18 e 96,90%, respectivamente. A análise de regressão demonstrou um efeito linear negativo quanto ao comprimento final e sobrevivência das larvas conforme aumentou-se o nível desse alimento. Dessa forma, conclui-se que o glúten de trigo é um ingrediente potencial para ser utilizado em dietas para tilápia-do-nilo, não sendo recomendada sua inclusão na fase larval.

The objective of this study was to evaluate the utilization potential of wheat gluten in diets for Nile tilapia (Oreochromis niloticus) through studies of digestibility and productive performance of larvae. For the digestibility study was elaborated a reference diet and a test diet containing wheat gluten. Chromium oxide-III was used as an inert marker. The collected faeces were destined to analysis of chemists compounds as the feed, and the test ingredient. Besides, reading chromium oxide analysis was performed in the faeces and diets. The results obtained through these analyses were used to calculate the digestibility coefficients. Based on these coefficients, experimental diets were elaborated for the dose-response studies in larvae. For the experiment, five experimental diets were formulated with different inclusion levels of wheat gluten, with 0%; 2,5%; 5,0%, 7,5% and 10%. At the end of the experiment, the productive performance was evaluated. The performance data were submitted to linear regression with 5% of probability. The wheat gluten presents high digestibility coefficients for dry matter, crude protein and gross energy with 94,02; 98.18 and 96.90%, respectively. The regression analyses showed a negative linear effect on the final length and survival of the larvae when the level of this food was increased. Thus, it is concluded that wheat gluten is a potential ingredient to be utilized in diets for Nile tilapia, not being recommended its inclusion in the larvae period.

Effect of different periods of pre-slaughter stress on the quality of the Nile tilapia meat

Abstract The study was carried out with the objective of evaluating the influence of pre-slaughter stress on meat quality of Nile tilapia (O. niloticus) for 10 days of storage in ice. 75 whole fish were used eviscerated, with average weight and length of 825.75 ± 101.59 g and 28.25 ± 0.81 cm, respectively. The treatments consisted of time in which the animals underwent pre-slaughter hypoxia, being 0, 3 and 6 minutes. Rigor mortis and muscle pH were assessed besides the application of the Quality Index Method and analysis of total protein and blood glucose. Rigor mortis did not differ among treatments during the storage period, and after three hours all animals were in rigor stage. The muscle pH values varied widely during the study period, observing higher values on the third day of storage. Sensory analysis showed that after 10 days the tilapia from the different treatments did not differ in the evaluated quality parameters similarly, there was no difference regarding the evaluated blood biochemical parameters Thus, hypoxia of 6 minutes pre-slaughter does not influence the rigor mortis, muscle pH, qualitative perception of the meat quality, total protein and blood glucose of Nile tilapia.