Transcriptome analysis of the Bactrian camel (Camelus bactrianus) reveals candidate genes affecting milk production traits

Abstract

Background Milk production traits are complex traits with vital economic importance in the camel industry. However, the genetic mechanisms regulating milk production traits in camels remain poorly understood. Therefore, we aimed to identify candidate genes and metabolic pathways that affect milk production traits in Bactrian camels. Methods We classified camels (fourth parity) as low- or high-yield, examined pregnant camels using B-mode ultrasonography, observed the microscopic changes in the mammary gland using hematoxylin and eosin (HE) staining, and used RNA sequencing to identify differentially expressed genes (DEGs) and pathways. Results The average standard milk yield over the 300 days during parity was recorded as 470.18 ± 9.75 and 978.34 ± 3.80 kg in low- and high-performance camels, respectively. Nine female Junggar Bactrian camels were subjected to transcriptome sequencing, and 609 and 393 DEGs were identified in the low-yield vs. high-yield (WDL vs. WGH) and pregnancy versus colostrum period (RSQ vs. CRQ) comparison groups, respectively. The DEGs were compared with genes associated with milk production traits in the Animal Quantitative Trait Loci database and in Alashan Bactrian camels, and 65 and 46 overlapping candidate genes were obtained, respectively. Functional enrichment and protein–protein interaction network analyses of the DEGs and candidate genes were conducted. After comparing our results with those of other livestock studies, we identified 16 signaling pathways and 27 core candidate genes associated with maternal parturition, estrogen regulation, initiation of lactation, and milk production traits. The pathways suggest that emerged milk production involves the regulation of multiple complex metabolic and cellular developmental processes in camels. Finally, the RNA sequencing results were validated using quantitative real-time PCR; the 15 selected genes exhibited consistent expression changes. Conclusions This study identified DEGs and metabolic pathways affecting maternal parturition and milk production traits. The results provides a theoretical foundation for further research on the molecular mechanism of genes related to milk production traits in camels. Furthermore, these findings will help improve breeding strategies to achieve the desired milk yield in camels. Graphical Abstract

Camel Milk: Antimicrobial Agents, Fermented Products, and Shelf Life

“…Proper nutrition, access to clean water, and regular veterinary care are essential for maintaining the health of camels and ensuring optimal milk production and quality [8]. Recent research has focused on the genomics of Bactrian camels and the candidate genes related to milk production traits were revealed by transcriptome analysis [9]. A total of 1185 genes related to milk traits, including milk yield, milk protein, milk fat, and milk lactose, were identified [10].…”

“…A total of 1185 genes related to milk traits, including milk yield, milk protein, milk fat, and milk lactose, were identified [10]. Twenty-seven candidate genes and 16 core signaling pathways were connected with maternal parturition, estrogen control, lactation initiation, and milk production features [9]. It was shown that milking camels twice a day can result in higher milk yield and better milk quality compared to milking once a day [11].…”

Molecular characterization of Cryptosporidium spp. in Bactrian camels (Camelus bactrianus) from Yili Kazak Autonomous Prefecture of Xinjiang, China

“…Camels play an important role in the grassland animal husbandry of this region, holding a crucial position in the frontier animal husbandry and the ethnic characteristic industries of Mongolian and Kazak in the frontier pastoral areas ( 6 ). The camel breeding industry has transitioned from nomadic to intensive breeding, providing humans with milk, meat, camel hair, and other products, thereby increasing the economic income of herdsmen ( 8 ). While there have been limited global studies on Cryptosporidium spp.…”