Abstract
This study aimed to investigate the effects of N-carbamylglutamate (NCG) supplementation on the follicular development of yaks to identify potential mechanisms essential for fertility in yaks. Twelve multiparous anoestrous female yaks were randomly assigned to two groups—Control (fed with a basal diet, n = 6) and NCG (basal diet supplemented with 6.0 g day−1 NCG, n = 6). Yaks in the NCG group had higher numbers of large follicles (>5 mm in diameter) than those in the Control group. An RNA-sequencing analysis of yak ovaries revealed a total of 765 genes were differentially expressed between experimental groups, of which 181 genes were upregulated and 584 genes were downregulated following NCG supplementation. The results of a transcriptome functional analysis, qRT-PCR validation, and immunohistochemistry revealed that NCG supplementation increased angiogenesis and de novo synthesis of cholesterol in yak ovaries. NCG was also found to upregulate the gene expression of steroidogenic enzymes. Based on this, it was concluded that NCG supplementation promotes the follicular development of yaks mainly by affecting cholesterol metabolism to initiate steroidogenesis in ovaries. The results provide evidence for understanding the mechanisms responsible for NCG promoting follicular development of female yaks, which may contribute to the development and application of NCG in animal reproduction.
Highlights
Yaks provide food, shelter, physical labour, and fuel for local herders living in high-altitude plateaus of China [1,2,3], making them an indispensable part of the pasture–livestock industry in these areas [4]
Only one dominant follicle continues to grow in the last follicular wave and becomes the mature ovulatory follicle (12–20 mm in diameter), while the remaining follicles in the original cohort undergo atresia [48,49]
We found that NCG supplementation enhanced the xCD31 signal intensity and vascular area percentage in ovaries and upregulated the gene expression of NOS2 and vascular endothelial growth factor A (VEGFA), indicating that NCG further promoted angiogenesis in yak ovaries
Summary
Yaks provide food (meat and dairy products), shelter (hair and hides), physical labour, and fuel (dung) for local herders living in high-altitude plateaus of China [1,2,3], making them an indispensable part of the pasture–livestock industry in these areas [4]. Yak husbandry has been seriously restricted due to their low reproductive efficiencies caused by their seasonal breeding characteristics, restricted oestrus cycles, and conception that only occurs in the warm season (July–October) [3,5]. A large proportion of yak cows experience long postpartum anoestrus periods and begin their oestrus cycles only two–three years after calving, rather than in the breeding season of the year [3,6]. Most yaks calve once every two years or twice in three years [5], with an average annual reproduction rate of 40–60% [3]. A straightforward strategy to shorten postpartum anoestrus periods and improve fertility in yaks might be to accelerate the resumption of postpartum follicular activity
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
