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1. Angiopoietin-like protein 4 (ANGPTL4) plays a key role in promoting fat metabolism and reducing blood lipid. This study characterised the ANGPTL4 gene in Muscovy ducks ( Cairina moschata ) and investigated its potential functions in fat metabolism in Muscovy ducks.2. The Muscovy duck ANGPTL4 cDNA was successfully cloned for the first time, showing a length of 2591 bp. After phylogenetic analysis by RT-qPCR analysis, it was found that the ANGPTL4 gene of Anas platyrhynchos shared the highest sequence similarity with that of Muscovy ducks.3. The ANGPTL4 gene was commonly expressed in 23 different tissues with the highest expression in the abdominal fat in Muscovy ducks. A significant association was observed between abdominal fat percentage (AFP) and the mRNA expression of the ANGPTL4 gene. Moreover, Muscovy ducks showed a peak of ANGPTL4 expression in the liver and abdominal fat at 1-2 weeks old.4. These findings suggest that the ANGPTL4 gene is related to fat deposition and regulation in Muscovy ducks.

The ileum is mainly responsible for food absorption and nutrients transportation. The microbes in its intestinal lumen play an essential role in the growth and health of the host. However, it is still unknown how the ileal microbes affect the body weight of the host. In this study, we used Muscovy ducks as an animal model to investigate the relationship between the ileal microbes and body weight and further explore the potential mechanism. The ileum tissue and ileal contents of 200 Muscovy ducks were collected for mRNA extraction and real-time quantitative PCR, as well as DNA separation and 16S rRNA gene sequencing. With body weight being ranked, the bottom 20% (n = 40) and top 20% (n = 40) were set as the low and high groups, respectively. Our results showed that in the ileum of Muscovy ducks, the Bacteroides, Firmicutes, and Proteobacteria were the predominant phyla with the 10 most abundant genera, namely Candidatus Arthromitus , Bacteroides , Streptococcus , Vibrio , Romboutsia , Cetobacterium , Clostridium sensu stricto 1 , Terrisporobacter , Escherichia-Shigella , and Lactobacillus. We identified Streptococcus , Escherichia-Shigella , Candidatus Arthromitus , Bacteroides , Faecalibacterium , and Oscillospira were closely correlated to the growth of Muscovy ducks. Streptococcus and Escherichia-Shigella were negatively related to body weight (BW), while Candidatus Arthromitus , Bacteroides , Faecalibacterium , and Oscillospira were positively associated with BW. In addition, we found that the relative expression levels of tight junction proteins ( Claudin 1 , Claudin 2 , ZO-1 and ZO-2 ) in the high group showed an upward trend, although this trend was not significant ( P > 0.05). The expression of pro-inflammatory factors ( IL-1β , IL-2 and TNF-α ) decreased in the high group, while the anti-inflammatory factor IL-10 increased. Of course, except IL-2 , these differences were not significant ( P > 0.05). Finally, the correlation analysis showed that Escherichia-Shigella was significantly positively correlated with IL-1β ( P < 0.05). These findings may provide fundamental data for the development of next-generation probiotics and assist the development of strategies for changing the gut microbiota to promote the growth performance in the duck industry., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Fu, Yang, Xiao, Wang, Yang, Lu, Wang and Lyu.)

Occludin is an important component of tight junction proteins and has been extensively studied in animals such as mice, chickens, geese, and pigs. As one of the most important waterfowl species in China, Muscovy duck (Cairina moschata) is an important economic animal for meat. However, research on the occludin gene in Muscovy duck is lacking. In the present study, Muscovy duck occludin cDNA was cloned for the first time. The length of the cDNA was 1,699 bp, and it showed a high sequence similarity with the Anser cygnoides domesticus and Gallus gallus occludin genes. The occludin gene was differentially expressed in the tissues of healthy ducks. The highest and lowest expressions of occludin were observed in the crop and the spleen, respectively. After the oral administration of Clostridium butyricum (CB), the occludin expression in the ileum of 7-day-old Muscovy ducks was significantly upregulated and subsequently showed a decreasing trend in 14-day-old Muscovy ducks. Under the early intervention of CB, no significant difference was observed in the occludin expression of cecum between the control and CB group. Collectively, these results suggest that CB plays an important role in regulating the expression of the occludin gene in Muscovy ducks, and adding CB in feed may maintain the intestinal barrier of ducks by regulating the expression of occludin., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Muscovy ducks are among the best meat ducks in the world. The objective of this study was to identify genes related to growth metabolism through transcriptome analysis of the ileal tissue of Muscovy ducks. Duck ileum samples with the highest (H group, n = 5) and lowest (L group, n = 5) body weight were selected from two hundred 70-day-old Muscovy ducks for transcriptome analysis by RNA sequencing. In the screening of differentially expressed genes (DEGs) between the H and L groups, a total of 602 DEGs with a fold change no less than 2 were identified, among which 285 were upregulated and 317 were downregulated. Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that glutathione metabolism, pyrimidine metabolism, and protein digestion and absorption processes played a vital role in regulating growth and metabolism. The results showed that 7 genes related to growth and metabolism, namely, ANPEP , ENPEP , UPP1 , SLC2A2 , SLC6A19 , NME4 , and LOC106034733 , were significantly expressed in group H, which was consistent with the phenotype results. The validation of these 7 genes using real-time quantitative PCR results indicated that the expression level of ENPEP was significantly different between the H and L groups ( P < 0.05). This study provides a theoretical basis for exploring the influence of the ileum on growth and metabolism in ducks., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Xingxin Wang et al.)

It is generally accepted that domestic ducks are valuable protein sources for humans. The gastrointestinal ecosystem contains enormous and complicated microbes that have a profound effect on the nutrition, immunity, health, and production of domestic ducks. To deeply understand the gastrointestinal microbial composition of domestic ducks, we investigated the microbiomes of 7 different gastrointestinal locations (proventriculus, gizzard, duodenum, jejunum, ileum, cecum, and rectum) and the short-chain fatty acids in 15 healthy muscovy ducks based on 16S rRNA gene sequencing, qPCR, and gas chromatography. As a result, 1 029 735 sequences were identified into 35 phyla and 359 genera. Firmicutes, Proteobacteria, Bacteroidetes, Cyanobacteria, and Actinobacteria were the major phyla, with Bacteroidetes being most abundant in the cecum. The population of the total bacteria and the representatives of the Firmicutes, Bacteroidetes, and Bacteroides groups increased from the proximal to the distal part of the GIT. Bacteroides was the most dominant group in the cecum. Acetate, propionate, and butytrate, as well as gene copies of butyryl-CoA including acetate-CoA transferase and butyrate kinase, were significantly higher in cecum than in other sections. Isobutyrate, valerate, and isovalerate were only found in the cecum. The differences of microbial composition and the short-chain fatty acids of their metabolites among these 7 intestinal locations might be correlated with differences in gut function. All these results provide a reference for the duck gastrointestinal microbiome and a foundation for understanding the types of bacteria that promote health and enhance growth performance and decrease instances of disease in duck breeding., (Copyright © 2020. Published by Elsevier Inc.)