Betaine, also known as trimethylglycine, is a naturally occurring compound found in sugar beets, spinach, and other plants. It plays a central role in cellular chemistry as a methyl donor, participating in reactions that regulate gene expression and protein function. But its most relevant property for heat-stressed animals is its role as an osmolyte, a molecule that helps cells retain water and maintain their internal balance when the body is losing fluid through sweating and panting. Because betaine is inexpensive and already approved as a feed additive in many countries, the researchers saw it as a practical candidate for protecting livestock welfare without requiring expensive infrastructure like cooling sheds.

The study, led by Jamal Nasir and Surinder S. Chauhan, is among the first to test betaine under conditions that mimic the increasingly common reality of hot nights. Most previous research on heat stress in sheep has assumed that animals can recover overnight when temperatures drop. But as climate patterns shift, nocturnal temperatures in many sheep-producing regions are rising too, meaning animals never fully recover from the day’s heat load. To capture this scenario, the team designed an experiment where heat-stressed lambs experienced daytime temperatures between 28 and 38 degrees Celsius with 40 to 60 percent relative humidity, followed by nights that stayed warm at 26 to 28 degrees Celsius.

Forty-eight crossbred lambs, a Merino, Border Leicester, and Dorset cross aged six to ten months, were randomly assigned to one of four groups in a two-by-two factorial design. Half were kept in thermoneutral conditions at 18 to 21 degrees Celsius, while the other half faced the heat stress regimen for fourteen days. Within each temperature group, lambs received either a control diet or a diet supplemented with 2 grams of betaine per day, a dose previously shown to be effective in heat-stressed sheep. The researchers then measured rectal temperature and respiration rate three times daily and collected blood and muscle samples to analyze plasma metabolites and antioxidant enzyme activities.

The results were striking. Under heat stress, lambs receiving betaine had significantly lower rectal temperatures at both the 9 a.m. and 1 p.m. measurements compared with control lambs. At 9 a.m., betaine-supplemented lambs averaged 39.6 degrees Celsius versus 39.7 degrees in controls, and by 1 p.m. the gap widened slightly to 40.1 versus 40.2 degrees. Respiration rate told a similar story: at the hottest point of the day, betaine-fed lambs breathed 181 times per minute compared with 194 in the control group. While these differences may seem modest on paper, they represent meaningful physiological relief for animals whose bodies are working overtime to dissipate heat.

Beyond the visible signs of heat strain, the researchers looked deeper into the biochemistry of stress. Plasma cortisol, a hormone released by the adrenal glands in response to stress, was significantly lower in betaine-supplemented lambs on day seven of the trial, measuring 15.8 nanograms per milliliter compared with 20.3 in controls. Lower cortisol suggests that betaine did not just mask the symptoms of heat stress but actually reduced the physiological burden the animals were experiencing. Chronically elevated cortisol can suppress immune function, reduce feed intake, and impair growth, so keeping it in check has real implications for animal welfare and productivity.

Perhaps the most technically significant findings came from the muscle tissue analysis. Lambs receiving betaine under heat stress showed markedly higher activity of two key antioxidant enzymes: glutathione peroxidase and catalase. Glutathione peroxidase activity rose from 54.1 to 75.6 nanomoles per minute per milligram of protein, while catalase activity more than doubled from 12.4 to 33.2 nanomoles per minute per milligram of protein. These enzymes form the front line of cellular defense against reactive oxygen species, unstable molecules that damage cell membranes, proteins, and DNA. Heat stress is known to accelerate the production of these damaging molecules, overwhelming the animal’s natural antioxidant systems and contributing to muscle damage, reduced growth, and poorer meat quality.

The mechanism behind betaine’s protective effect likely involves several converging pathways. As an osmolyte, betaine helps cells maintain volume and function under the dehydration stress that accompanies heavy panting and sweating. As a methyl donor, it supports the production of S-adenosylmethionine, which is involved in synthesizing glutathione, the molecule that glutathione peroxidase uses to neutralize peroxides. By bolstering both the physical resilience of cells and the biochemical machinery that cleans up oxidative damage, betaine appears to address heat stress from multiple angles simultaneously. The researchers note that this dual action may explain why the supplement produced measurable improvements in both physiological indicators and enzymatic defenses.

The implications for the sheep industry are considerable. Heat stress costs livestock producers billions of dollars annually through reduced weight gain, lower fertility, increased mortality, and compromised product quality. As extreme heat events become more frequent and prolonged, and as warm nights increasingly prevent overnight recovery, the problem is expected to intensify. The study’s authors suggest that dietary betaine supplementation could serve as a cost-effective strategy to safeguard lamb welfare and productivity under these changing conditions. Unlike structural interventions such as shade structures or cooling systems, which require significant capital investment, betaine can simply be added to existing feed rations at minimal cost.

While the findings are promising, the researchers acknowledge that further work is needed to determine optimal dosing strategies, long-term effects, and whether the benefits extend to other livestock species and production systems. The study was conducted over fourteen days with a specific breed cross under controlled conditions, and real-world farming environments introduce additional variables such as exercise, variable feed intake, and fluctuating weather. Nevertheless, the research represents an important step toward practical, science-based nutritional interventions that can help livestock adapt to a warming world. The work was supported by Japan’s Society for the Promotion of Science through its Program for Forming Japan’s Peak Research Universities, and the full paper is available open access for producers, researchers, and policymakers interested in building more climate-resilient livestock systems.

Subject of Research: Effects of dietary betaine supplementation on physiological stress responses and antioxidant enzyme activity in heat-stressed lambs

Article Title: Dietary betaine supplementation improves oxidative status and ameliorates the negative effects of heat stress in lambs

Article References: Nasir, J., Hiraishi, M., Dunshea, F. R., Warner, R. D., McGill, D., & Chauhan, S. S. (2026). Dietary betaine supplementation improves oxidative status and ameliorates the negative effects of heat stress in lambs. Discover Sustainability. https://doi.org/10.1007/s43621-026-05001-y

Image Credits: AI Generated

DOI: 10.1007/s43621-026-05001-y

Keywords: betaine, heat stress, lambs, antioxidant enzymes, cortisol, animal welfare, livestock, oxidative stress, climate change, sheep nutrition, thermoregulation, Discover Sustainability

The experiment took place at the Lafareg research farm in Beja, a sub-humid zone receiving around 558 millimeters of rain annually. Twenty-eight five-month-old fat-tailed Barbarine ram lambs, weighing on average 22.5 kilograms, were divided into four groups of seven, balanced by body weight. Two groups were housed in stalls and fed 400 grams of concentrate per day with oat hay available freely. The other two groups rotationally grazed a cultivated vetch pasture, receiving the same daily concentrate allowance. Within each system, one group received an extra 100 grams of acacia foliage per head per day, offered an hour before the main feed, while the other received none. The acacia is a tannin-rich legume widespread in Tunisia, containing roughly 60 grams of condensed tannins per kilogram of dry matter, and it was chosen as a natural alternative to the antibiotic growth promoters that have been banned in many regions over concerns about toxic residues in meat.

The chemical analysis of the feeds explains much of what followed. The fresh vetch grass contained 21.9 percent crude protein, more than three times the 6.7 percent found in the hay offered indoors. The concentrate supplied 16.2 percent protein, and the acacia itself 12.6 percent. Because grazing lambs could harvest this protein-dense forage directly, their total dry matter intake reached 1,342 to 1,442 grams per day, compared with only 839 to 960 grams for the stall-fed animals. Grazing lambs derived about 70 percent of their intake from forage, eating nearly a kilogram of vetch daily, while stall-fed lambs drew 47 percent of their ration from concentrate and consumed less than half as much forage as their pastured counterparts.

Growth told the same story in striking numbers. Lambs on pasture gained an average of 180 grams per day, while stall-fed lambs gained 141 grams. The extremes were even more revealing: the fastest-growing group was pasture-fed lambs without acacia, at 192 grams per day, and the slowest was stall-fed lambs without acacia, at 110 grams. The statistical interaction between feeding system and tannin supply was significant, meaning the effect of the supplement could not be judged in isolation from the basal diet. Indoors, where nitrogen arrived as true protein in hay and concentrate, the tannins appeared to offer a slight benefit, consistent with the well-documented ability of condensed tannins at low doses to bind dietary protein in the rumen and protect it from degradation, thereby increasing the flow of amino acids to the small intestine.

On pasture, however, the chemistry worked differently. The nitrogen in fresh vetch is largely in soluble form, which tannins cannot bind in the same protective way, and the vetch biomass itself already carries measurable tannins, averaging around 360 milligrams of catechin equivalents per kilogram of dry matter. Adding acacia on top of this tannin-bearing forage apparently pushed total tannin intake toward a range where the compounds begin to work against the animal, suppressing feed intake, rumen microbial activity, and digestive enzyme function. The authors note that previous work has shown low to moderate tannin inclusion can be neutral or beneficial, while larger amounts reduce nutrient digestibility and growth. The lesson is that tannins are not a simple additive but a dietary variable whose consequences hinge on context.

At slaughter, the pasture advantage carried through to the carcass. Grazing lambs were heavier at slaughter, had higher empty body weights, and produced both heavier hot and cold carcasses. Their commercial dressing percentage averaged 45.8 percent against 40.5 percent for stall-fed lambs. The non-carcass components also reflected the different lives the animals had led: grazing lambs developed larger red organs, including heart, liver, and lungs, and heavier kidneys, a pattern the authors attribute to the greater physical activity of animals ranging over pasture. Testis weight was higher in both pasture groups and in the tannin-supplemented stall group compared with unsupplemented stall-fed lambs, while gut weights were similar across all treatments.

Within the carcass itself, the feeding system shaped the proportions of most commercial joints, including the leg, shoulder, loin, breast, and, notably, the signature fat tail of the Barbarine breed. Pastured lambs carried tails averaging 950 grams, about 6.05 percent of carcass weight, compared with 615 grams and 4.7 percent in stalled lambs. Muscle proportions were highest in unsupplemented stall-fed lambs, while fat deposition was greater in both pasture groups and in tannin-supplemented stall lambs, an outcome that runs counter to earlier studies in which grazing animals, burning more energy on movement, laid down less fat. Across all groups, the leg and shoulder together accounted for roughly 34 percent and 20 percent of the tailed carcass, supporting the principle of anatomic harmony, the idea that joint proportions remain consistent within a breed regardless of rearing conditions.

Perhaps the most commercially reassuring finding concerned the meat itself. Neither the feeding system nor the acacia supplement produced meaningful differences in pH measured one hour and 24 hours after slaughter, in water loss during cooking, in color coordinates of lightness, redness, and yellowness, or in the chemical composition of the longissimus dorsi muscle, including dry matter, ash, protein, and intramuscular fat. Lightness values averaged 43.5 across all groups, comfortably above the threshold of 34 at or above which meat is deemed acceptable by 95 percent of consumers. Trained panelists who roasted samples from each group and scored tenderness, juiciness, flavor, and overall acceptability on nine-point scales found the meat moderately tender, between 5.7 and 6, and moderately juicy, between 5.1 and 5.8, with no distinctive off-flavors and no differences among treatments. Every sample was judged acceptable.

The broader significance of the study lies in its demonstration that natural feed additives cannot be evaluated in a vacuum. Condensed tannins have attracted intense interest as antioxidants, antimicrobials, and rumen-protective compounds that could replace banned growth promoters, but their biological activity is a double-edged sword, beneficial at low doses and detrimental at high ones. This trial shows that the dose that matters is the total dose delivered by the whole diet, not just the supplement spooned out on top. A hundred grams of acacia that gently shields protein in a hay-based ration becomes an excess burden when the lambs are already browsing tannin-bearing vetch. For producers of fat-tailed breeds like the Barbarine, the practical takeaways are twofold: well-managed grazing on protein-rich cultivated pasture remains the most effective route to faster growth and heavier carcasses, and tannin supplementation should be matched carefully to the basal forage. The authors call for further research to define optimal inclusion levels and dose-response relationships under different feeding conditions, work that will help determine whether tannin-rich foliage can take its place as a reliable tool in sustainable, antibiotic-free lamb production.

Subject of Research: Effects of Acacia cyanophylla condensed tannin supplementation and grazing versus feedlot feeding on growth, carcass traits, and meat quality of Barbarine lambs

Article Title: Effects of Acacia cyanophylla-condensed tannin supply on growth performance, carcass characteristics and meat quality of fat-tailed Barbarine lambs studied under grazing conditions or in a feedlot

Article References: Yagoubi, Y., Atti, N., Smeti, S., Abidi, J., & Mahouachi, M. (2026). Effects of Acacia cyanophylla -condensed tannin supply on growth performance, carcass characteristics and meat quality of fat-tailed Barbarine lambs studied under grazing conditions or in a feedlot. Archives Animal Breeding, 69(3), 495-505. https://doi.org/10.5194/aab-69-495-2026

Image Credits: AI Generated

DOI: 10.5194/aab-69-495-2026

Keywords: Barbarine lambs, Acacia cyanophylla, condensed tannins, grazing, feedlot, carcass quality, meat quality, sheep nutrition, sustainable livestock, vetch pasture, animal growth, Tunisia

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