Background: Cage-rearing in laying ducks, as a novel rearing system, not only fundamentally solves the pollution problem of the duck industry and improve bio-safety and product quality but also exhibits more benefits by implementing standardized production compared with the floor-rearing. Of course, this system also brings some welfare problems and stress injuries to layers due to lack of water environment and limited activities in the cages. However, the effects on the factors of antioxidant defense and inflammatory injury in the early cage stage are not well-understood. Results: In this study, eighty Shaoxing layers were reared on floor and in cages from 12 weeks of age. The ducks were caged 1, 2, 4, 7, and 10 days, the factors of antioxidant defense and inflammatory injury were investigated. The results showed that the caged ducks suffered liver injury to a certain extent when the ducks were just put into the cages. Analysis of antioxidant enzyme activities indicated that the different rearing system could not affect the change of antioxidant capacities, while the liver malondialdehyde (MDA) level was significant higher in the 2-d, 7-d, and 10-d ducks compared with the 1-d ducks during the change of days, while catalase (CAT) activity showed the opposite results. Additionally, quantitative real-time PCR (qRT-RCR) revealed that the relative mRNA levels of endoplasmic reticulum (ER) stress-related gene (CHOP and GRP78) were significantly upregulated in cage rearing ducks compared to that of the floor rearing ducks. Moreover, the mRNA levels of inflammatory cytokines including cycloxygenase-2 (COX-2), nitric oxide synthase (iNOS), Interleukin 1 beta (IL-1β), Interleukin 2 (IL-2) and Interleukin 6 (IL-6), were also increased significantly in caged layers. Conclusions: Taken together, although antioxidant defense has no obvious effect on cage stress, the stress levels of laying ducks vary greatly in the early cage stage, which not only caused liver tissue damage to some extent, but also resulted in increases in the expression of the factors of inflammatory injury. Therefore, we recommend that anti-stress agents should be added in the feed to alleviate the stress in the early cage stage.

Broodiness is an unfavorable trait associated with the cessation of egg laying. Studies have found that excessive granulosa cell apoptosis and autophagy occur during goose broodiness. Other studies have also confirmed that oxidative stress is an important cause of apoptosis and autophagy. However, whether oxidative stress occurs during goose broodiness and whether this oxidative stress causes apoptosis and autophagy have not been fully elucidated. In this study, we investigated the effects of oxidative stress on the autophagy and apoptosis of granulosa cells in broody geese. The results showed higher mRNA expression of genes related to antioxidative stress responses (GPX, SOD-1, SOD-2, COX-2, CAT and hsp70) in pre-broody and broody geese than in laying birds. In addition, increased levels of granulosa cell apoptosis and autophagy were observed in pre-broody geese than in laying geese. Additionally, granulosa cells treated with H₂O₂ exhibited increased apoptosis and autophagy in vitro, and these effects were responsible for goose granulosa cell death. Moreover, vitamin E treatment effectively protected granulosa cells from H₂O₂-induced oxidative stress by inhibiting ROS production. Correspondingly, granulosa cell apoptosis and autophagy were greatly alleviated by vitamin E treatment. Together, our results demonstrated serious oxidative stress and granulosa cell apoptosis and autophagy in broody geese, and oxidative stress promoted apoptosis and autophagy. Vitamin E alleviated the autophagy and apoptosis of granulosa cells by inhibiting oxidative stress.

The volatile aroma compounds in raw duck meat strongly affect consumers’ purchase decisions and they vary among breeds with different growth rates. In this study, slow-growing (SG) Liancheng White and fast-growing (FG) Cherry Valley ducks were selected, and their volatile compounds were characterized using electric nose and gas chromatography-mass spectrometry. Furthermore, a widely targeted metabolomics approach was used to investigate the metabolites associated with volatile compounds. The results showed that hexanal, nonanal, octanal, heptanal, and 2-pentylfuran were abundantly present in duck meat, regardless of the breed. The higher nonanal and octanal rates contributed to the fatty and fruity aroma in SG meat than FG meat, while FG meat had a mushroom note resulting from higher octenol. Furthermore, widely targeted metabolomics showed a lower carnitine content in SG meat, which might promote lipid deposition to produce more octanal and nonanal. Higher sugar and amino acid contents led to a meaty aroma, whereas more trimethylamine N-oxide may generate a fishy note in SG meat. Taken together, this study characterized the raw duck meat aroma and provided the basic mechanism of the formation of the key volatile compound.

The photoperiod is the predominant environmental factor that governs seasonal reproduction in animals; however, the underlying molecular regulatory mechanism has yet to be fully elucidated. Herein, Yangzhou geese (Anser cygnoides) were selected at the spring equinox (SE), summer solstice (SS), autumn equinox (AE), and winter solstice (WS), and the regulation of seasonal reproduction via the light-driven cyclical secretion of pineal melatonin was investigated. We show that there were seasonal variations in the laying rate and GSI, while the ovarian area decreased 1.5-fold from the SS to the AE. Moreover, not only did the weight and volume of the pineal gland increase with a shortened photoperiod, but the secretory activity was also enhanced. Notably, tissue distribution further revealed seasonal oscillations in melatonin receptors (Mtnrs) in the pineal gland and the hypothalamus–pituitary–gonadal (HPG) axis. The immunohistochemical staining indicated higher Mtnr levels due to the shortened photoperiod. Furthermore, the upregulation of aralkylamine N-acetyltransferase (Aanat) was observed from the SS to the AE, concurrently resulting in a downregulation of the gonadotrophin-releasing hormone (GnRH) and gonadotropins (GtHs). This trend was also evident in the secretion of hormones. These data indicate that melatonin secretion during specific seasons is indicative of alterations in the photoperiod, thereby allowing for insight into the neuroendocrine regulation of reproduction via an intrinsic molecular depiction of external photoperiodic variations.

Spaghetti meat (SM) is a newly identified muscle abnormality that significantly affects modern broiler chickens, consequently exerting a substantial economic impact on the poultry industry worldwide. However, investigations into the meat quality and the underlying causative factors of SM in broilers remain limited. Therefore, this study was undertaken to systematically evaluate meat quality and muscle fiber characteristics of SM-affected meat. To elucidate the disparities between SM-affected and normal (NO) muscles in broiler chickens reared under identical conditions, we selected 18 SM-affected breast tissues and 18 NO breast tissues from 200 broiler chickens raised according to commercial standards under the same conditions for our study. The results showed that compared with the NO group, the muscle surface of the SM group lost integrity, similar to strip and paste. The brightness and yellowness values were significantly higher than those of the NO group. On the contrary, the shear force and protein were significantly lower in the SM group. Microscopic examination revealed that the muscle fibers in the SM group were lysed, necrotic, and separated from each other, with a large number of neutrophils diffusely distributed on the sarcolemma and endometrium. Thirty-five significantly different metabolites were observed in the breast muscles between both groups. Among them, the top differential metabolites—14,15-DiHETrE, isotretinoin, L-malic acid, and acetylcysteine—were mainly enriched in lipid metabolism and inflammatory pathways, including linoleic acid, arachidonic acid, phenylalanine, and histidine metabolism. Overall, these findings not only offer new insights into the meat quality and fiber traits of SM but also contribute to the understanding of potential mechanisms and nutritional regulators for SM myopathy.