Impact of divergence of residual feed intake on triglyceride metabolism-related gene expression in meat-type ducks.

Triglyceride (TG) metabolism is a key factor that affects residual feed intake (RFI); however, few studies have been conducted on the related gene expression in poultry. The aim of the present study was to investigate the expression of genes and their associations with RFI in meat-type ducks. Weight gain and feed intake (FI) at an age 21-42 days were measured and the RFI was calculated. Quantitative PCR was used to test the expression of the six identified genes, namely peroxisome proliferator activated receptor γ (PPARγ), glycerol kinase 2 (GK2), glycerol-3-phosphate dehydrogenase 1 (GPD1), glycerol kinase (GYK), lipase E (LIPE), and lipoprotein lipase (LPL) in the duodenum in the high RFI (HRFI) and low RFI (LRFI) groups. The results demonstrated that daily feed intake, feed conversion ratio (FCR), and RFI were markedly higher in HRFI ducks than those in LRFI ducks. Moreover, the levels of expression of PPARγ, GK2, and LIPE were significantly higher in the LRFI group than those in the HRFI group. Correlation analysis showed that PPARγ, GK2, and LIPE were significantly negatively associated with FCR and RFI. Furthermore, gene expression levels were negatively associated with the measured phenotype. The association of GK2 with PPARγ, GPD1, LPL, and LIPE was positive. The relationship between the TG related gene and RFI was further verified to potentially develop pedigree poultry breeding programs. The results of this study suggested that the expression of genes correlated with TG metabolism and transport is up-regulated in the duodenum of ducks with high feed efficiency. PPARγ, GK2, and LIPE are important genes that affect RFI. The results of the present study provide information that could facilitate further explorations of the mechanism of RFI and potential markers at the molecular and cellular levels.

Identification of stable reference genes for quantitative gene expression analysis in the duodenum of meat-type ducks.

Quantitative polymerase chain reaction (qPCR) is an important method to detect gene expression at the molecular level. The selection of appropriate housekeeping genes is the key to accurately calculating the expression level of target genes and conducting gene function studies. In this study, the expression of eight candidate reference genes, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), beta-actin (ß-actin), 18S ribosomal RNA (18S rRNA), hydroxymethylbilane synthase (HMBS), hypoxanthine phosphoribosyltransferase 1 (HPRT1), TATA box binding protein (TBP), ribosomal protein L13 (RPL13), and tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein (YWHAZ), in the duodenal epithelial tissue of 42-day-old meat-type ducks were detected using qPCR. Furthermore, their expression stability was analyzed using the geNorm, NormFinder, and BestKeeper programs. The results indicated that HMBS and YWHAZ were the most stably expressed genes. All three programs indicated that the expression of 18S rRNA was the least stable, making it unsuitable for the study of gene expression in meat-type duck tissues. This study provides stable reference genes for gene expression analysis and contributes to further studies on the gene function of meat-type ducks.

Mitochondrial genome and phylogenetic analysis of Chaohu duck.

A complete mitochondrial genome sequence is important for the accurate determination of phylogenetic relationships. Chaohu duck is a dominant native breed in Anhui Province, China. We aimed to ascertain the complete mitochondrial genome sequence of Chaohu duck via high-throughput sequencing and primer walking. Phylogenetic analysis of Chaohu duck was performed following Kimura 2-parameter model. The total length of the mitogenome was 16,597 bp, and comprised 29.2 %A, 22.2 % T, 32.8 % C, and 15.8 % G. It included 2 ribosomal RNA genes, 13 protein-coding genes, 22 transfer RNA genes and a control region (D-loop). Furthermore, the haplotype diversity and nucleotide diversity values were 0.9028(Hd) and 0.01162(Pi) respectively. This indicates that Chaohu duck has high population diversity. Twenty-two haplotypes were identified in sixty Chaohu ducks which were divided into two haplogroups. Therefore, we inferred that Chaohu duck may originate from Anas platyrhynchos, and was influenced by Anas poecilorhyncha during evolution. Our results provide mitochondrial genome information for further studies on Chaohu ducks and lays a foundation for germplasm resources conservation.

The spread of Tembusu virus in China from 2010 to 2019.

Tembusu virus (TMUV) is a positive-sense RNA virus that is associated with severe reduction in egg production and even death in ducks. TMUV infection shows high incidence and is a threat to the global duck industry. However, the possible origin, genotype, and codon usage bias of TMUV are not very clear. Here, we addressed these questions by analyzing the available genomic sequences from China. The results showed that the ancestor of avian TMUV was most likely a mosquito TMUV. Moreover, three TMUV clades were identified by three different phylogenetic analysis methods. The TMUV genome exhibits a stronger mutation pressure than natural selection pressure. Our findings provide important insights that reveal the ongoing TMUV spread in China and can aid in future prevention and control.