Bingqiang Dong

Abdominal fat deposition is an important economic trait in poultry, as excessive accumulation reduces feed efficiency and carcass yield. The gut microbiota is known to influence host energy metabolism and fat storage, suggesting its potential involvement in fat deposition. This study examined the relationship between intestinal microbiota and abdominal fat deposition in an F₂ population derived from Cherry Valley Ducks (♂) × Runzhou Crested White Ducks (♀) at 42 days of age. Based on abdominal fat rate, ducks with values of 0–0.75% and 1.5–2.25% were defined as the low (LF) and high (HF) abdominal fat groups, respectively. A combined multi-omics approach was used, including 16S rRNA gene sequencing, metagenomics, and whole transcriptomics, to compare high and low abdominal fat rate groups. 16S rRNA gene sequencing results showed that the cecum had the highest microbial diversity among all intestinal segments (duodenum, jejunum, ileum, and rectum) and was significantly enriched in carbohydrate metabolism pathways, highlighting its key role in nutrient utilization and growth. Therefore, the cecum was selected for further analysis. Metagenomic analysis of the cecum contents revealed significantly different intestinal microbial β diversity between the high and low abdominal fat rate groups (p < 0.05). The low abdominal fat rate group was enriched in beneficial microorganisms such as Paenibacillus, Butyrivibrio, Coprococcus, Ruminococcaceae, Veillonellaceae (Clostridiales), and Firmicutes. Conversely, the high abdominal fat rate group was characterized by an increased abundance of Bacteroidetes, including both beneficial and potentially pathogenic taxa such as Alistipes and Eggerthellales. The integrated analysis of metagenomic and whole transcriptome sequencing showed that Firmicutes and Bacteroidetes were not only related to energy metabolism, lipid metabolism, and amino acid metabolism, but also to the expression of FGF2, FKBP5, PNPLA2, PLIN3, FGFR2, DGAT2, and ACER2. In addition, Firmicutes and Bacteroidetes were also associated with 7 lncRNAs: XR_003493494.1, XR_003492471.1, XR_001190174.3, TCONS_00005095, XR_001190238.3, TCONS_00005095, and XR_003492841.1. In conclusion, this study highlights that the cecal microbiota is closely associated with abdominal fat deposition in ducks, elucidating its potential influence on host metabolism and gene expression. These findings enhance our understanding of the gut microbiota’s relationship with obesity and offer new strategies to modulate gut–microbe interactions to reduce abdominal fat accumulation in poultry.

Excessive deposition of abdominal fat will cause a waste of resources. In order to explore the key miRNAs and circRNA/lncRNA-miRNA-mRNA ceRNA regulatory network involved in regulating abdominal fat deposition, hematoxylin and eosin (H&E) staining was performed on abdominal fat tissues of ducks in the high abdominal fat rate group (HF) and low abdominal fat rate group (LF) at 21 and 42 days of age, and whole transcriptome sequencing was performed on abdominal tissues of ducks in the HF and LF groups at 42 days of age. The results showed that the number of adipocytes in ducks in the HF group was significantly higher than that in the LF group at 21 days of age (p < 0.001), while the number of adipocytes in ducks in the HF group at 42 days of age was significantly lower than that in the LF group (p < 0.001). In addition, transcriptome sequencing screened out a total of 14 differentially expressed miRNAs (10 miRNAs were significantly up-regulated, and 4 miRNAs were significantly down-regulated). By predicting the target genes of these differentially expressed miRNAs, a total of 305 target genes were obtained. Further analysis of miRNA target genes using GO and KEGG functional enrichment analyses revealed that these target genes were significantly enriched in the GnRH signaling pathway, the PPAR signaling pathway, insulin resistance, the mTOR signaling pathway, the AMPK signaling pathway, the FoxO signaling pathway, and other pathways related to adipose development. In addition, miRNA-205-x, miRNA-6529-x, miRNA-194-x, miRNA-215-x, miRNA-3074-x, miRNA-2954-x, novel-m0133-3p, and novel-m0156-5p were found to be important candidate miRNAs for abdominal fat deposition in ducks. These miRNAs were related to the expression of FOXO3, LIFR, Pdk4, PPARA, FBN1, MYH10, Cd44, PRELP, Esrrg, AKT3, and STC2. Based on these eight candidate miRNAs, a ceRNA regulatory network of circRNA/lncRNA-miRNA-mRNA regulating abdominal fat deposition was successfully constructed. The results of this study will provide a useful reference for accelerating the understanding of the molecular mechanism of duck abdominal fat deposition.

The imbalance in polyunsaturated fatty acid (PUFA) composition in human food is ubiquitous and closely related to obesity and cardiovascular diseases. The development of n-3 PUFA-enriched poultry products is of great significance for optimizing fatty acid composition. This study aimed to improve our understanding of the effects of dietary linseed oil on hepatic metabolism using untargeted metabolomics and 4D label-free proteome analysis. A total of 91 metabolites and 63 proteins showed differences in abundance in duck livers between the high linseed oil and control groups. Pathway analysis revealed that the biosynthesis of unsaturated fatty acids, linoleic acid, glycerophospholipid, and pyrimidine metabolisms were significantly enriched in ducks fed with linseed oil. Meanwhile, dietary linseed oil changed liver fatty acid composition, which was reflected in the increase in the abundance of downstream metabolites, such as α-linolenic acid (ALA; 18:3n-3) as a substrate, including n-3 PUFA and its related glycerophospholipids, and a decrease in downstream n-6 PUFA synthesis using linoleic acid (LA; 18:2n-6) as a substrate. Moreover, the anabolism of PUFA in duck livers showed substrate-dependent effects, and the expression of related proteins in the process of fatty acid anabolism, such as FADS2, LPIN2, and PLA2G4A, were significantly regulated by linseed oil. Collectively, our work highlights the ALA substrate dependence during n-3 PUFA synthesis in duck livers. The present study expands our knowledge of the process products of PUFA metabolism and provides some potential biomarkers for liver health.

Abdominal fat deposition is an important trait in meat-producing ducks. F2 generations of 304 Cherry Valley and Runzhou Crested White ducks were studied to identify genes and lncRNAs affecting abdominal fat deposition. RNA sequencing was used to study abdominal fat tissue of four ducks each with high or low abdominal fat rates. In all, 336 upregulated and 297 downregulated mRNAs, and 95 upregulated and 119 downregulated lncRNAs were identified. Target gene prediction of differentially expressed lncRNAs identified 602 genes that were further subjected to Gene Ontology and KEGG pathway analysis. The target genes were enriched in pathways associated with fat synthesis and metabolism and participated in biological processes, including Linoleic acid metabolism, lipid storage, and fat cell differentiation, indicating that these lncRNAs play an important role in abdominal fat deposition. PPAPA, FOXO3, FASN, PNPLA2, FKBP5, TCF7L2, BMP2, FGF2, LIFR, ZBTB16, SIRT, GYG2, NCOR1, and NR3C1 were involved in the regulation of abdominal fat deposition. PNPLA2, TCF7L2, FGF2, LIFR, BMP2, FKBP5, GYG2, and ZBTB16 were regulated by the lncRNAs TCONS_00038080, TCONS_0033547, TCONS_00066773, XR_001190174.3, XR_003492471.1, XR_003493494.1, XR_001192142.3, XR_002405656.2, XR_002401822.2, XR_003497063.1, and so on. This study lays foundations for exploring molecular mechanisms underlying the regulation of abdominal fat deposition in ducks and provides a theoretical basis for breeding high-quality meat-producing ducks.