The objective of this work was to evaluate the influence of slaughter weight on the expression of calpastatin, mcalpain and the RyR3 gene, and on the chemical composition, morphometric measurements, fillet yield and sensorial characteristics of Nile tilapia fillets. In the experiment, 90 Nile tilapia were divided into three experimental treatments regarding slaughter weight (n = 30): in treatment 1, tilapia aged 140 days were slaughtered with an average body weight of 665 ± 85 g; in treatment 2, the animals were slaughtered at 182 days and weighed 1000 ± 177 g; and in treatment 3, they were slaughtered at 238 days and weighed 1325 ± 167 g. There was no significant difference (P > .05) between the treatments for the chemical composition and fillet yield. Fillets of tilapia slaughtered with a weight of 665 g presented higher expression of mcalpain and lower expression of calpastatin gene, lower pH values of the thawed fillet, lower drip and thawing loss, and lower shear force than animals slaughtered with the highest evaluated weight. Tilapias slaughtered at 665 g also presented higher flavor and general acceptance. These results show that slaughter weight may influence important aspects of the quality of Nile tilapia fillets and that the slaughter of Nile tilapia with a body weight of 665 g allows fillets that serve the consumer market to be obtained.

A strategy to mitigate the negative effects of stress on animals is to enhance their ability to beneficially respond to stressful conditions. This study aimed to assess whether prenatal ambient temperature influences the response of Japanese quail (Coturnix coturnix japonica) chicks to environmental challenges during growth. The experiment was conducted in a 2 × 2 factorial arrangement: two temperature conditions for the mothers (thermoneutral and heat stress by continuous exposure to 32 °C) and two offspring ambient temperature conditions (thermoneutral and heat stress by intermittent exposure to 34 °C for 6 h/day from 15 to 35 days of age). Heat stress in mothers led to lower laying rate, egg mass, expression of methionine sulfoxide reductase A (MSRA) gene, and antioxidant capacity as well as higher chick mortality rate (1–15 days of age). Maternal heat stress led to lower weight gain and total antioxidant capacity and higher feed conversion ratio. Maternal temperature × Offspring temperature interaction effects were observed on carbonylated protein content and HSP70, GSS, and MSRA gene expression. It was observed that, for chicks hatched from heat-stressed mothers, exposure to heat stress led to higher carbonylated protein content and HSP70 expression than exposure to thermoneutral conditions. Maternal heat stress was also responsible for increasing GSS expression in chicks grown under thermoneutral conditions. Chicks hatched from non-stressed mothers and subjected to heat stress had higher MSRA expression compared to chicks maintained in a thermoneutral environment. Our results show that, although maternal heat stress had no negative effects on performance or oxidative metabolism of offspring grown under thermoneutral conditions, it was associated with lower performance and higher protein oxidation in offspring exposed to heat stress during growth. These results could be due in part to alterations in the expression of genes related to antioxidant capacity.

Since cinnamon has vitamins and minerals in addition to antioxidants compounds in its chemical composition studies have shown the potential of cinnamon supplementation on some important characteristics in the performance of birds. Thus, this study was conducted under the hypothesis that the inclusion of cinnamon in the laying quail diet could influence the performance of the birds through the expression of genes related to antioxidant activity and lipid metabolism. To test this hypothesis, 144 Japanese quail (Coturnix japonica) with an initial age of 18 weeks and average weight of 133g were distributed in a completely randomized design with two treatments: no cinnamon supplementation (NCS—control group) and with supplementation of 9g/kg of cinnamon powder (CPS). The experiment lasted for 84 days. At the end of the experimental period, six animals from each treatment were euthanized by cervical dislocation, blood was collected and organs weighed. Liver tissue was collected for gene expression and biochemical analyses. We observed a significant effect of cinnamon inclusion on the weight of the pancreas (P = 0.0418), intestine (P = 0.0209) and ovary (P = 0.0389). Lower weights of the pancreas and intestine, and a higher ovary weight was observed in birds receiving the CPS diet. Quails fed with cinnamon supplementation also had better feed conversion per egg mass (2.426 g /g, P = 0.0126), and higher triglyceride (1516.60 mg/dL, P = 0.0207), uric acid (7.40 mg/dL, P = 0.0003) and VLDL (300.40 mg/dL, P = 0.0252) contents. A decreased content of thiobarbituric acid reactive substances (TBARS) and lower catalase activity was observed in the liver of quails from the CPS diet (0.086 nmoles/mg PTN, and 2.304 H2O2/min/mg PTN, respectively). Quails from the CPS group presented significantly greater expression of FAS (fatty acid synthase, 36,03 AU), ACC (Acetyl-CoA Carboxylase, 31.33 AU), APOAI (apolipoprotein A-I, 803,9 AU), ESR2 (estrogen receptor 2, 0.73 AU) SOD (superoxide dismutase, 4,933.9 AU) and GPx7 (glutathione peroxidase 7, 9.756 AU) than quails from the control group. These results allow us to suggest that cinnamon powder supplementation in the diet of laying quails can promote balance in the metabolism and better performance through the modulation of antioxidant activity and the expression of genes related to lipid metabolism.

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