Zebrafish breeding program: genetic parameters estimates for growth traits.

The objective of this study was to evaluate the genetic parameters of two generations of zebrafish breeding program. The base population was formed by crossing individuals of six commercial stocks of zebrafish, resulting in a nucleus with 60 families. Two generations were evaluated, with a total of 780 and 781 individuals for the first and second generation, respectively. The selection was made based on the mean genetic value of each family, followed by mass selection of the breeders. Mathematical models that considered the fixed (age, density in the larval stage, sex, and generation) and random (animal additive genetics, common to full-sibs, and residual) effects were evaluated using BLUPF90 program family. Weight and total length were used as response variables. Total length was the best selection criterion because it had a higher heritability (0.30) than weight (0.22). There was a high common to full-sib effect, especially in the first generation of animals. For second-generation data, the heritability was 0.26 for total length, as well as a lower common to full-sib effect for length. The best model obtained for this evaluation was considering all effects, being age and density as first and second polynomial, respectively. The genetic and phenotypic correlations for weight and length were 0.87 and 0.75, respectively. These results indicate that genetic breeding using total length as the selection criterion may produce a larger and heavier zebrafish strain.

Quality and sensory acceptability of fish fillet (Oreochromis niloticus) with alginate-based coating containing essential oils.

The quality and sensory acceptability of fish fillet (Oreochromis niloticus) with alginate-based coating containing ginger and oregano essential oils (EO) were evaluated. The antioxidant activity of essential oil, coating, and fish were also investigated. In relation to lipid oxidation, a decrease was observed in fish with the edible coatings compared to the control being the coating with oregano EO the most effective and also with the highest antioxidant activity. Loss in color and weight were significantly lower with coating. Fish with coating maintained firmness whereas fish without coating became softer. Fish with edible coating and oregano essential oils showed higher sensory acceptability regarding to odor evaluated by consumers. Thus, edible coatings with essential oils as natural antioxidant improved the product quality and sensory acceptability.

Consumer profile and acceptability of cooked beef steaks with edible and active coating containing oregano and rosemary essential oils.

Fresh animal products are highly perishable and characterized by a short shelf-life. Edible coatings with natural antioxidants (essential oils: EOs) could improve stability, ensure quality, and increase the shelf-life of fresh products. Due to the strong flavor of EOs, their use should consider consumer preferences and sensory acceptability. This study evaluated the effects of edible coating (with oregano and rosemary essential oil) on beef in relation to consumer preferences, besides the determination of habits of consumption and buying intentions of consumers. Acceptability scores from three clusters of consumers was described. Coating with oregano was the preferred. The higher consumer acceptance and willingness to buy this product indicate a great potential and possibility of using coatings with essential oils in fresh animal products.

Genetic parameters for growth performance, fillet traits, and fat percentage of male Nile tilapia (Oreochromis niloticus).

Improvement of fillet traits and flesh quality attributes are of great interest in farmed tilapia and other aquaculture species. The main objective of this study was to estimate genetic parameters for fillet traits (fillet weight and fillet yield) and the fat content of fillets from 1136 males combined with 2585 data records on growth traits (body weight at 290 days, weight at slaughter, and daily weight gain) of 1485 males and 1100 females from a third generation of the Aquaamerica tilapia strain. Different models were tested for each trait, and the best models were used to estimate genetic parameters for the fat content, fillet, and growth traits. Genetic and phenotypic correlations were estimated using two-trait animal models. The heritability estimates were moderate for the fat content of fillets and fillet yield (0.2-0.32) and slightly higher for body weight at slaughter (0.41). The genetic correlation between fillet yield and fat was significant (0.6), but the genetic correlations were not significant between body weight and fillet yield, body weight and fat content, daily weight gain and fillet yield, and daily weight gain and fat content (- 0.032, - 0.1, - 0.09, and - 0.4, respectively). Based on the genetic correlation estimates, it is unlikely that changes in fillet yield and fat content will occur when using growth performance as a selection criterion, but indirect changes may be expected in fat content if selecting for higher fillet yield.

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.