Micronutrients and Concentrate Levels Reshape Rumen Genes in Cold-Adapted Ewes

On the windswept Hulunbuir grassland of northern China, where winters are long and bitterly cold, sheep have evolved remarkable physiological strategies for survival. A new pilot study published in the journal Stress Biology offers an unprecedented look at how one of these strategies plays out at the molecular level, revealing that simple changes to a ewe’s diet can rewire the gene activity of the rumen, the fermentation chamber that supplies most of a ruminant’s energy. The findings, though preliminary, hint at nutritional levers that could help livestock thrive in some of the planet’s harshest grazing environments.

The research team, led by scientists at the Institute of Subtropical Agriculture of the Chinese Academy of Sciences together with collaborators at Hulun Buir State Farm, focused on lactating Hulunbeier ewes, a hardy breed raised almost entirely outdoors on the alpine steppe. During winter, local herders typically house their flocks in unheated barns and feed little more than hay and a modest amount of simple concentrate, a regime that can leave breeding ewes short of roughly 30 percent of their nutritional requirements at a time when lactation demands extra energy. The researchers hypothesized that these sheep have developed environmentally adaptive traits that nutrition might be able to modify.

To test the idea, thirty healthy lactating Hulunbeier ewes with an average body weight of about 55.5 kilograms were randomly divided into three dietary groups. All received the same rapeseed straw roughage, but the concentrate differed. One group received 550 grams per day of a local concentrate as a control, a second received the same amount of a formulated concentrate enriched with a micronutrient premix of vitamins and trace elements, and a third received a larger 700-gram daily ration of the formulated concentrate. After 37 days, rumen epithelial tissue was collected and subjected to RNA sequencing, generating more than 281 million clean reads across eleven animals.

An exploratory comparison with lowland Hu sheep, drawn from previously published data, showed a clear separation between the two breeds in their global rumen transcriptomes. Hulunbeier sheep displayed a suggestive trend toward enhanced expression of genes involved in energy metabolism, including ATP5MC2, ATP5PO and UQCRH, along with components of the mitochondrial respiratory chain such as NDUFA2 and NDUFA7. Hu sheep, by contrast, preferentially expressed genes tied to lipid metabolism and signal transduction. This pattern echoes what has been reported in other high-altitude ruminants, such as Tibetan sheep, where mitochondrial efficiency appears to support the elevated thermogenic demands of cold exposure. The authors stress that because the comparison data came from different studies, this breed-level interpretation is hypothesis-generating only.

The dietary interventions produced more directly attributable effects. Comparing ewes fed the micronutrient-fortified formulated concentrate with those on the local control concentrate revealed 65 differentially expressed genes. Notably, the formulated diet upregulated CYP1A1 and LOC101119706, genes encoding cytochrome P450 enzymes that are central to detoxifying ruminal toxins such as ethanol and other xenobiotics. Enriched pathways included arachidonic acid metabolism, folate biosynthesis, steroid hormone biosynthesis and the metabolism of xenobiotics by cytochrome, while Gene Ontology terms highlighted immune response, defense response and response to oxidative stress. The authors suggest that micronutrient supplementation may bolster the rumen’s chemical defenses, though immune chemokine genes such as CXCL13 and CXCL14 were conversely downregulated, possibly reflecting the dietary shift.

Raising the concentrate level to 700 grams per day had a far larger molecular footprint, producing 1,004 differentially expressed genes. Upregulated genes clustered around biosynthetic processes, including folate, steroid hormone and amino acid biosynthesis, consistent with the anabolic push of a richer diet. Downregulated genes, however, were concentrated in cellular signaling pathways such as cGMP-PKG signaling, calcium signaling and focal adhesion, hinting that high concentrate intake may come at a cost to the efficiency of cellular communication within the rumen epithelium, a finding consistent with earlier reports linking high-concentrate diets to epithelial dysfunction and acidosis risk.

Perhaps the most striking result concerns thermogenesis, the heat-producing machinery that helps cold-adapted animals survive. Gene Set Enrichment Analysis showed significant activation of thermogenesis pathways in the high-concentrate group, with a normalized enrichment score of 1.57 and an FDR q-value of 0.027. Within this activated pathway, 14 genes were differentially expressed, including components of the electron transport chain such as NDUFA11, NDUFA13 and NDUFAB1, alongside the carnitine-acylcarnitine translocase gene SLC25A29. The authors propose a metabolic flexibility model in which the high-concentrate group compensates for a dampened Gs protein and p38 MAPK signaling axis by ramping up fatty acid oxidation and electron transport, channeling surplus energy into heat production, a strategy well suited to animals facing cold stress.

Volatile fatty acids, the short-chain fatty acids produced by rumen microbes that supply up to 70 percent of a ruminant’s energy, also showed diet-dependent gene expression shifts. The transporter gene SLC16A1 was more highly expressed in the control group, while genes involved in VFA metabolism, including PCCA, BCKDHB and MLYCD in propanoate metabolism and HMGCS1 in butanoate metabolism, differed significantly among groups. Computational network analysis predicted an association between HMGCS1 and the transcription factor PPARA, which may be involved in VFA metabolism in response to micronutrient supplementation, though the authors emphasize this remains a computational prediction requiring direct experimental testing.

The study’s authors are careful to frame their conclusions as preliminary. With only four, four and three animals in the three sequencing groups, no independent qPCR validation, and cross-breed comparisons confounded by differing experimental conditions, the findings are explicitly hypothesis-generating. The trial itself was conducted under relatively mild conditions with an average temperature of 11.5 degrees Celsius, meaning the observed transcriptomic patterns reflect breed background and nutritional intervention rather than acute cold exposure. Larger cohorts, parallel breed comparisons under controlled conditions and correlated phenotypic measurements will be needed to confirm the molecular mechanisms at play.

Even so, the work opens a compelling window into how nutrition and environment interact in the livestock genome. For herders on the Hulunbuir steppe and in other extreme environments worldwide, the prospect of tailored micronutrient premixes and carefully calibrated concentrate levels offers a low-tech intervention with potentially high-tech molecular consequences. By understanding which genes respond to which feeds, researchers hope to develop targeted nutritional strategies that enhance ruminant production, resilience and welfare in breeds shaped by some of the toughest climates on Earth, turning the rumen from a black box into a blueprint for precision agriculture.

Subject of Research: Transcriptomic adaptation of the rumen epithelium in alpine-adapted Hulunbeier ewes in response to micronutrient premix and concentrate supplementation

Article Title: Rumen epithelial functional adaptation in alpine ewes: transcriptomic effects of micronutrient premix and concentrate supplementation levels

Article References: Cheng, J., Cheng, Y., Zhang, B., Gebeyew, K., Yan, A., Hu, F., Li, J., Liu, J., Zhao, W., Kang, J., Tan, Z., & He, Z. (2026). Rumen epithelial functional adaptation in alpine ewes: transcriptomic effects of micronutrient premix and concentrate supplementation levels. Stress Biology, 6(1), Article 56. https://doi.org/10.1007/s44154-026-00324-2

Image Credits: AI Generated

DOI: 10.1007/s44154-026-00324-2

Keywords: rumen epithelium, Hulunbeier sheep, micronutrients, concentrate supplementation, transcriptomics, RNA-seq, thermogenesis, volatile fatty acids, alpine adaptation, PPARA, detoxification, sheep nutrition