The number of thoracolumbar vertebrae is a quantitative trait positively correlated with the economic traits of livestock. More thoracolumbar vertebrae individuals could genetically be used to improve the livestock population, as more thoracolumbar vertebrae means a longer carcass, which could bring more meat production. Nuclear receptor subfamily 6 group A member 1 (NR6A1) is considered a strong candidate gene for effecting the number of vertebrae in livestock. The purposes of this study are as follows: (a) Analyzing the effect of TLN variation on body size and carcass traits of Dezhou donkey; (b) Studying the distribution of seven single nucleotide variants (SNVs) in NR6A1 gene of Dezhou donkey; (c) Exploring the relationship between latent SNVs and TLN, the body size and carcass traits. We examined the thoracic and lumbar vertebrae number and seven SNVs in NR6A1 gene of 455 Dezhou donkeys, and analyzed the relationships between them. Five types of thoracolumbar combinations (T17L5 (individual with 17 thoracic and five lumbar vertebrae) 2.4%, T18L5 75.8%, T19L5 1.1%, T17L6 11.9%, and T18L6 8.8%) of Dezhou donkeys were detected in this study. For one thoracolumbar vertebra added, the body length of Dezhou donkey increases by 3 cm and the carcass weight increases by 6 kg. Seven SNVs (g.18093100G > T, g.18094587G > T, g.18106043G > T, g.18108764G > T, g.18110615T > G, g.18112000C > T and g.18114954T > G) of the NR6A1 gene were found to have a significant association with the TLN, body size and carcass traits of Dezhou donkey (p < 0.05), respectively. For instance, g.18114954C > T is significantly associated with lumber vertebrae number, the total number of thoracolumbar, and carcass weight, and individuals with TT genotype had significantly larger value than CC genotype (p < 0.05). Using these 7SNVs, 16 different haplotypes were estimated. Compared to Hap3Hap3, individuals homozygous for Hap2Hap2 showed significantly longer length in one thoracic spine (STL), the total thoracic vertebrae and one thoracolumbar spine. Our study will not only extend the understanding of genetic variation in the NR6A1 gene of Dezhou donkey, but also provide useful information for marker assisted selection in donkey breeding program.

Intramuscular fat (IMF) is an important factor affecting meat quality, but lipid and metabolic profiles of donkey meat remain unclear. The present study was conducted to investigate lipid characteristics in different parts of Dezhou donkey using lipidomics. The results show that IMF was more abundant in longissimus dorsi muscle (LDM) than rump muscle (RM) and hamstring muscle (HM), and mainly composed of triglycerides (TGs) rich in saturated fatty acid (SFAs) and monounsaturated fatty acid (MUFAs). A total of 1143 lipids belonging to 14 subclasses were identified in donkey meat, of which 73 lipids (23 upregulated and 50 downregulated) including glycerolipids (GLs), glycerophospholipids (GPs) and sphingolipids (SPs) were significantly different and are therefore potential biomarkers in LDM versus RM versus HM analyses (variable importance in projection >1, p < 0.05). Notably, 21 TGs upregulated in LDM were rich in MUFAs at sn-1 and SFAs at 2 and 3 positions of TG. Donkey muscle accumulated far more SFAs at the sn-3 position of TG, while more SFAs were present at the sn-1 positions of phosphatidylcholine (PC) and phosphatidylethanolamine (PE), and the percentages of SFAs at the three positions in TG, PC, and PE in the LDM group were much higher. The abundance of MUFAs at the sn-2 positions of TG, PC, and PE was significantly greater than in sn-1 or 3 positions, and the percentages of 18:1n-9 at the sn-1 and 2 position of TGs in LDM were significantly higher than in RM and HM groups. Polyunsaturated fatty acids (e.g.,18:2n-6, 18:3n-3, and 20:4n-6) tended to occur at the sn-1 position in TG, but at the sn-2 position in PC and PE. Significantly differential lipids were mainly enriched in GP, GL, and SP pathways, all considered key pathways for regulating IMF. The results reveal the components, structures and metabolic pathways of lipid molecules in donkey meat, and provide novel insight into the development of donkey meat products and accurate regulation of IMF.Practical Application: Intramuscular fat (IMF) is an important factor affecting meat quality, which is directly related to meat flavor, juiciness, and tenderness, but lipid and metabolic profiles of IMF remain unclear. The current results

 PCR-SSCP was used to screen variation in three regions of ovine KRT83.  No variation was found in the promoter region.  Two and five variants were found for exon 2 and exon 3-4 regions.  Seven SNPs were identified in these variants.  Variation in KRT83 affects GFW, wool Yield and fibre diameter-associated traits.

Intramuscular fat (IMF) and visceral adipose tissue (VAT) are both lipids, but have significantly different deposition processes. Furthermore, the heterogeneity of lipid molecular characteristics and mechanisms is unclear. Accordingly, this study used non-targeted lipidomics and transcriptomics to analyze the lipid profiles and metabolism of longissimus dorsi muscle (LDM) and VAT from donkeys. A total of 1,146 and 1,134 lipids belonging to 18 subclasses were identified in LDM and VAT, respectively, with LDM having higher glycerophospholipid (GP) and lower glycerolipid (GL) contents. Polyunsaturated fatty acids (PUFAs) were distributed preferentially at the sn-1 positions in triglycerides (TGs), and sn-2 positions in phosphatidylcholine (PC) and phosphatidylethanolamine (PE). The percentage PUFA content in TGs was significantly lower in LDM than in VAT, while the opposite trend was observed for PUFAs in PC and PE. A total of 110 different lipid molecules (72 downregulated and 38 upregulated) were identified in LDM compared with VAT, of which 11 were considered potential lipid markers. These different lipids were involved in 17 metabolic pathways, including GL and GP metabolisms. Of the 578 differentially expressed genes screened, 311 were downregulated and 267 were upregulated in LDM compared with VAT. Enriched ontology analysis of the differentially expressed genes mainly involved sphingolipid signaling pathways, and GP, GL, and sphingolipid metabolisms. Overall, lipidomics and transcriptomics indicated differences in lipid profiles and metabolism in LDM and VAT, providing new perspectives for the study of heterogeneity in IMF and VAT.

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Heat cooking of meat gives it a specific taste and flavor which are favored by many consumers. While the characteristic taste components of chicken, duck, pig, and seafood have been studied, there is a lack of information about the molecular components that give donkey meat its unique taste. Here, the characterization profiles of raw donkey meat (RDM) and cooked donkey meat (CDM) meat by metabonomics and lipidomics. The results showed that a total of 186 metabolites belonging to 8 subclasses were identified in CDM and RDM, including carbohydrates (27.42%), amino acids (17.20%), lipids (13.44%), and nucleotides (9.14%). In total, 37 differential metabolites were identified between CDM and RDM. Among these, maltotriose, L-glutamate, and L-proline might predominantly contribute to the unique umami and sweet taste of donkey meat. Comprehensive biomarker screening detected 9 potential metabolite markers for the discrimination among RDM and CDM, including L-glutamate, gamma-aminobutyric acid, and butane-1, 2, 3, 4-tetrol. Moreover, a total of 992 and 1,022 lipids belonging to 12 subclasses were identified in RDM and CDM, respectively, mainly including triglycerides (TGs) and glycerophospholipids (GPs). Of these lipids, 116 were significantly different between CDM and RDM. The abundances of 61 TGs rich in saturated and monounsaturated fatty acids were retained in CDM, whereas the abundances of 37 GPs rich in polyunsaturated fatty acids were reduced, suggesting that TGs and GPs might be the predominant lipids for binding and generating aroma compounds, respectively. A total of 13 lipids were determined as potential markers for the discrimination among RDM and CDM, including PC(O-16:2/2:0), LPE(22:5/0:0), and PC(P-16:0/2:0). In conclusion, this study provided useful information about the metabolic and lipid profiles of donkey meat which may explain its unique taste and flavor, which could serve as a basis for the development and quality control of donkey meat and its products.

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Several studies have shown the association between the ligand-dependent nuclear receptor compression-like protein (LCORL) gene and body size in horses, pigs and donkeys. Based on previous studies, the LCORL gene was hypothesized to be associated with growth traits and hide weight in Dezhou donkeys. In this study, we aimed to reveal the variation of the LCORL gene in the Dezhou donkey and explore whether the gene is associated with hide weight and body size. In this study, genetic polymorphisms in the LCORL gene of the Dezhou donkey were studied using targeted sequencing technology, and single nucleotide polymorphisms (SNPs) of the LCORL gene were analyzed for association with hide weight and body size in Dezhou donkeys. The results showed that there was an SNP locus situated in intron 1 of the LCORL gene. Association analysis revealed that individuals with the GG genotype had significantly higher body height, body length, chest circumference and hide weight than those with the AA genotype (p < 0.05). Therefore, the g.112558859 A > G locus can be used as a potential candidate marker affecting body size and hide weight. This study provides the foundation for breeding high-quality donkeys with high hide yield.