Effects of cage and floor rearing system on the factors of antioxidant defense and inflammatory injury in laying ducks

Abstract

BackgroundCage-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.ResultsIn 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.ConclusionsTaken 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.

RNA-seq and differential expression analysis of the duck transcriptome: The effect of short-term cage-rearing

“…According to previous study, cage-rearing stress gradually subsides after the 4 th day (ZHANG et al 2019). Herein, there was a decrease in the expression of the CRH gene although there was no significant difference in the expression of the ACTH gene (Proopiomelanocortin, POMC).…”

“…Previous research showed that cage-rearing can cause endoplasmic reticulum stress and lead to liver injury in ducks. It was also reported that there was an increase in the expression levels of inflammation-related factors and immune-related genes (ZHANG et al 2019). It is noteworthy that changes in the external environment affect the transcriptome of an organism (KRISHNAN et al 2020;WANG et al 2020;XU et al 2019).…”

“…Compared to chicken husbandry, such factors as body size, dabbling, fecal ejection and other habits, complicate the design, manufacture and production of ducks. Additionally, the acute and chronic stress caused by cage rearing are also crucial issues that need to be addressed by duck producers(Z hang et al 2019). In the cage rearing system, the high-density husbandry causes spatial stress to the ducks.…”

Changes in production performance, antioxidant capacity and immune status of meat ducks under different rearing systems

“…Results showed these parameters were coherently lower in NRS ducks at different ages, demonstrating NRS was better for duck liver health despite the lipid deposition enhancement and liver developmental retardation. And this also showed an advantage over CRS, as ducks suffered liver injury once they were just put into cages [35]. Furthermore, antioxidant capacity prevents cell damage from free radicals and other reactive oxygen species (ROS) to avoid oxidative stress (the imbalance between ROS and antioxidants) [36,37].…”

“…The concentration of MDA and activities of SOD, GSH-Px are effective indicators to re ect the antioxidant status of ducks [38,39]. A study on Shaoxing ducks showed rearing systems did not have signi cant impacts on the activity of MDA, SOD, CAT, T-AOC, and GSH-Px in the liver [35]. Another study though only determined the total antioxidant capacity (T-AOC) in serum, results showed no signi cant difference between FRS and NRS [5].…”