RESUMO
OBJECTIVE: The study was designed to investigate the effects of restraint method, restraint duration, and body weight on stress-linked hormones (corticosterone, adrenaline, and noradrenaline), blood biochemical (namely glucose and lactate), and the meat quality in broiler chickens. METHODS: A total of 120 male broiler chickens (Cobb 500) were assigned to a 2×3×2 factorial arrangement in a completely randomized design using two restraint methods (shackle and cone), three durations of restraint (10, 30, and 60 s), and two categories of live body weight (1.8±0.1 kg as lightweight and 2.8±0.1 kg as heavyweight). RESULTS: Irrespective of the duration of restraint and body weight, the coned chickens were found to have lower plasma corticosterone (p<0.01), lactate (p<0.001), lower meat drip loss (p<0.01), cooking loss (p<0.05), and higher blood loss (p<0.05) compared with their shackled counterparts. The duration of restraint had significant effects on the meat initial pH (p<0.05), ultimate pH (p<0.05), and yellowness (p<0.01). The lightweight broilers exhibited higher (p< 0.001) blood loss and lower (p<0.05) cooking loss compared to the heavyweight broilers, regardless of the restraint method used and the duration of restraint. However, the interaction between the restraint method, duration of restraint, and body weight contributed to differences in pre-slaughter stress and meat quality. Therefore, the interaction between the restraint method and the duration of restraint affected the meat shear force, lightness (L*) and redness (a*). CONCLUSION: The duration of restraint and body weight undoubtedly affect stress responses and meat quality of broiler chickens. Regardless of the duration of restraint and body weight, the cone restraint resulted in notably lower stress, lower meat water loss, and higher blood loss compared to shackling. Overall, the findings of this study showed that restraint method, duration of restraint, and body weight may affect the stress response and meat quality parameters in broilers and should be considered independently or interactively in future studies.
RESUMO
Xist (inactivated X chromosome specific transcript) is a prototype long noncoding RNA in charge of epigenetic silencing of one X chromosome in each female cell in mammals. In a genetic screen, we identify Mageb3 and its homologs Mageb1 and Mageb2 as genes functionally required for Xist-mediated gene silencing. Mageb1-3 are previously uncharacterized genes belonging to the MAGE (melanoma-associated antigen) gene family. Mageb1-3 are expressed in undifferentiated ES cells and early stages of in vitro differentiation, a critical time window of X chromosome inactivation. Mageb3 showed both cytoplasmic and nuclear localization without enrichment on the inactive X (Xi). Mageb3 interacted with Polycomb group ring finger 3 (Pcgf3), a RING finger protein involved in recruiting Polycomb activities onto Xi. Mageb3 overexpression stabilized Pcgf3 protein. Mageb1-3 gene knockout affected H3K27me3 enrichment and the spreading of gene silencing along Xi. These data suggested that Mageb3 might regulate the recruitment of the Polycomb complex onto Xi and subsequent H3K27me3 modification through Pcgf3. Moreover, the nucleolar enrichment of Mageb3 was diminished when nuclear matrix factor hnRNP U is overexpressed, implying the interaction between Mageb3 and nuclear matrix, which is another possible mechanism for Mageb3 to regulate X chromosome inactivation.