Differential Analysis of Proteomes among Camel Meat from Different Ages

The differences in the proteomes of camel meat from different age groups were analyzed by tandem mass tag (TMT)-based quantitative proteomics and liquid chromatography tandem mass spectrometry (LC-MS/MS) to identify the key quality-related proteins of camel meat. The results showed that differentially expressed proteins (DEPs) had an important effect on the quality of camel meat. A total of 311 DEPs were identified in the longissimus dorsi muscle of camels from three age groups, 3–4 (I), 6–7 (II), and 9–10 (III) years old. Altogether 245 DEPs were identified in groups I versus II, 16 in groups II versus III, and 139 in groups I versus III. In addition, 194, 1, and 110 DEPs were up-regulated, and 51, 15, and 29 DEPs were down-regulated in the three comparison groups, respectively. Gene Ontology (GO) functional annotation analysis indicated that structural proteins, metabolic proteins, and heat stress proteins could be used as biomarkers for discrimination among camel meat from different ages. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the DEPs were mainly involved in fatty acid metabolism, glycolysis/glucose production, amino acid biosynthesis, and the hypoxia inducible factor-1 (HIF-1) signaling pathway. Protein-protein interaction (PPI) analysis showed that metabolic enzyme proteins were key network-connecting proteins that affect camel meat from different ages. Correlation analysis showed that 16 DEPs were correlated closely with meat tenderness. The tenderness of camel meat from the three age groups was mainly influenced by actin, histone and protein kinases. The results of this study can provide a scientific basis for the grading and evaluation of camel meat, the selection of optimal slaughter age, and the study of camel meat quality characteristics

Analysis of Differential Muscle Metabolites in Bactrian Camels Slaughtered at Different Ages by Non-Targeted Metabolomics Based on Ultra-high Performance Liquid Chromatography-Mass Spectrometry

In this study, non-targeted metabolomics based on ultra-high performance liquid chromatography Q-Exactive-mass spectrometry (UPLC-Q-Exactive-MS) was used to explore the differences in the metabolite profiles of muscles from Bactrian camels slaughtered at different ages. The results showed that a total of 710 differentially expressed metabolites (DEMs) were identified in the longissimus dorsi muscle of camels from three age groups: I (3–4 years old), II (6–7 years old), and III (9–10 years old). In total, 78 DEMs were found in groups I vs II, of which 47 were upregulated in group I and 31 were upregulated in group II. Totally, 49 DEMs were identified in groups II vs III, of which 18 were upregulated in group II and 31 were upregulated in group III. In addition, 65 DEMs were identified in groups I vs III, of which 29 were upregulated in group I and 36 were upregulated in group III. The results of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the DEMs were mainly enriched in pathways such as protein and amino acid metabolism, fatty acid metabolism, and vitamin and mineral metabolism, indicating that the digestion and metabolism of various nutrients in camels were different at different growth stages. The contents of polyunsaturated fatty acids (PUFA) (especially n-6 PUFA and n-3 PUFA) and the PUFA/unsaturated fatty acid (UFA) ratio were significantly higher in group I than III, which was mainly related to the significant upregulation of arachidonic acid, linoleic acid and 13-L-hydroperooleic acid concentrations in relevant metabolic pathways. Meanwhile, DEMs such as L-leucine, L-valine, and L-glutamine could serve as potential markers for evaluating the quality change of camel meat at different slaughter ages

Effects of Age and Muscle Type on the Chemical Composition and Quality Characteristics of Bactrian Camel (Camelus bactrianus) Meat

Camel meat could have health benefits for human consumers due to its nutritional value. The influence of age and muscle type on the chemical composition and quality characteristics of Bactrian camel meat was examined in the present study. Samples of the Longissimus thoracic (LT), Semitendinosus (ST), and Psoas major (PM) muscles were collected from a total of fifteen male camels in three different age groups (3–4 years, 6–7 years, and 9–10 years). The younger camels exhibited higher values of moisture, polyunsaturated fatty acids, ultimate pH, cooking loss, and lightness, but lower fat, shear force, and redness values compared to meat collected from older camels. The LT muscle had higher fat and color parameters (lightness, redness, yellowness) but lower shear force values than the ST and PM muscles (p < 0.05). The ST muscles had a higher content of n-6 polyunsaturated fatty acids and n-3 polyunsaturated fatty acids but lower cooking loss values than the LT and PM muscles. These results indicated that younger camels provide better meat quality traits than older camels. The results of the present study will improve the marketing of Bactrian camel meat products and will provide more information about the most suitable muscles and the optimal slaughter age

A Genome-Wide Association Study Identifies Quantitative Trait Loci Affecting Hematological Traits in Camelus bactrianus

Bactrian camels (Camelus bactrianus) are one of the few large livestock species that can survive in the Gobi Desert. Animal immunity and disease resistance are related to hematological traits, which are also associated with tolerance observed in Bactrian camels. However, no genome-wide association studies have examined the genetic mechanism of the immune capability of Bactrian camels. In the present study, we used genotyping-by-sequencing data generated from 366 Bactrian camel accessions to perform a genome-wide association study for 17 hematological traits. Of the 256,616 single-nucleotide polymorphisms (SNPs) obtained, 1,635 trait–SNP associations were among the top quantitative trait locus candidates. Lastly, 664 candidate genes associated with 13 blood traits were identified. The most significant were ZNF772, MTX2, ESRRG, MEI4, IL11, FRMPD4, GABPA, NTF4, CRYBG3, ENPP5, COL16A1, and CD207. The results of our genome-wide association study provide a list of significant SNPs and candidate genes, which offer valuable information for further dissection of the molecular mechanisms that regulate the camel’s hematological traits to ultimately reveal their tolerance mechanisms

Effects of Various Processing Methods on the Nutritional Quality and Carcinogenic Substances of Bactrian Camel (Camelus bactrianus) Meat

Bactrian camel (Camelus bactrianus) meat, as a product of national geographical indication, is mainly produced in the northwest regions of China. This study systematically evaluated the edible quality, nutritional quality, and carcinogenic substances of Bactrian camel meat using different heating times in four thermal processing methods (steaming, boiling, frying, and microwaving). Compared with the control group (uncooked), the thermal processing of meat demonstrated lower redness and moisture content; higher shear force values and protein, fat, and ash contents; and sharply increased the levels of amino acids and fatty acids. The moisture content of the fried and microwave-treated meat was significantly lower than that of the steamed and boiled meat (p < 0.05). Steamed meat was higher in protein but had a lower fat content than the other three processing methods (p < 0.05). Compared with frying and microwaving, meat from steaming and boiling showed higher levels of essential amino acids and lower shear force values. However, the smoke generated during frying led to the formation of large amounts of polycyclic aromatic hydrocarbons (PAHs) and nitrites, and the levels of these substances increased with heating time. In addition, with the extension of the heating time, the shear force of the meat also increased gradually (p < 0.05). In summary, steaming and boiling were proven to be suitable processing methods for preserving better nutritional values while delivering less carcinogenic risk. With our results, we have established a nutritional database for Bactrian camel meat, providing a reference for selecting a suitable thermal processing method

Antibacterial Activity of Trypsin-Hydrolyzed Camel and Cow Whey and Their Fractions

Antibacterial peptides were isolated and purified from whey proteins of camel milk (CaW) and cow milk (CoW) and their antimicrobial activities were studied. The whey proteins were hydrolyzed using trypsin, and the degree of hydrolysis was identified by gel electrophoresis. The whey hydrolysate (WH) was purified using ultrafiltration and Dextran gel chromatography to obtain small peptides with antibacterial activity. The effect of the antimicrobial peptides on the morphology of bacterial strains was investigated using transmission electron microscopy. Their amino acid composition and antimicrobial activities were then determined. Polypeptides CaWH-III (<3 kDa) and CoWH-III (<3 kDa) had the strongest antibacterial activity. Both Fr.A2 (CaWH-Ⅲ’s fraction 2) and Fr.B1 (CoWH-Ⅲ’s fraction 1) had antibacterial effects toward Escherichia coli and Staphylococcus aureus, with minimum antimicrobial mass concentrations of 65 mg/mL and 130 mg/mL for Fr.A2, and 130 mg/mL and 130 mg/mL for Fr.B1, respectively. The highly active antimicrobial peptides had high amounts of alkaline amino acids (28.13% in camel milk Fr.A2 and 25.07% in the cow milk Fr.B1) and hydrophobic amino acids. (51.29% in camel milk Fr.A2 and 57.69% in the cow milk Fr.B1). This results showed that hydrolysis of CaW and CoW using trypsin produced a variety of effective antimicrobial peptides against selected pathogens, and the antibacterial activity of camel milk whey was slightly higher than that of cow milk whey