The review, led by Anand Jejal and colleagues at the ICAR-National Dairy Research Institute in Karnal, India, synthesised evidence from a systematic search of the Scopus database covering the years 2000 to 2026. After applying strict eligibility criteria, the team distilled the field down to 17 core studies that explicitly examined ramie as feed, including in vivo feeding trials in ruminants, in vitro rumen fermentation experiments and agronomic assessments of forage management. The authors screened titles and abstracts independently, resolved disagreements through discussion, and followed the PRISMA 2020 reporting guidelines. They deliberately excluded studies focused purely on textile processing or on phytoremediation, the use of plants to extract heavy metals from contaminated soil, unless the biomass had also been evaluated for feeding purposes. A bibliometric keyword co-occurrence analysis using VOSviewer software revealed three dominant research themes: nutritional evaluation and digestibility, zootechnical performance in animals, and rumen fermentation dynamics.

Botanically, ramie is a vigorous perennial herb native to East Asia, propagated mainly through rhizome cuttings or root division rather than seed. This vegetative propagation confers a practical advantage for forage producers: genetic uniformity across the stand, which translates into consistent biomass quality from harvest to harvest. The crop thrives in warm, humid conditions with optimal temperatures between 25 and 30 degrees Celsius, and under intensively managed tropical fodder systems it can be cut up to 14 times per year, with upper-bound yields reaching approximately 300 tonnes of fresh material, or about 42 tonnes of dry matter, per hectare annually. The authors caution that these figures represent the ceiling of what has been achieved under specific climatic and management conditions rather than typical farm-level outputs. Ramie’s deep and extensive root system allows it to extract subsoil water during dry spells, and its capacity for osmotic adjustment helps it tolerate moderate drought, traits that give it a yield-stability edge over alfalfa, Napier grass and maize when water becomes limiting.

The nutritional case for ramie rests on a strikingly good chemical profile. Crude protein content in whole-plant forage generally falls between 15 and 24 percent of dry matter, placing it well above most tropical grasses and in the same league as high-quality legumes such as lucerne. Leaf-rich samples harvested on a 30-day interval have even approached 29 percent crude protein on a dry-matter basis. In vitro dry matter digestibility values range from 55 to 70 percent, depending on cultivar, harvest interval and plant part, while estimated metabolizable energy contents fall between 8.5 and 10.5 megajoules per kilogram of dry matter. The fibre fractions are moderate, with neutral detergent fibre between 45 and 60 percent and acid detergent fibre between 30 and 40 percent, enough to support rumination without depressing intake. The mineral profile is less straightforward: calcium is often abundant, exceeding 0.8 percent of dry matter, but phosphorus is comparatively low, producing a wide calcium-to-phosphorus ratio that demands careful ration formulation, particularly for high-producing dairy animals.

One of the most intriguing aspects of ramie’s chemistry is its content of condensed tannins, secondary plant compounds with a double-edged nutritional role. At moderate concentrations, tannins bind to dietary protein in the rumen and shield it from excessive microbial degradation, increasing the flow of so-called bypass protein to the small intestine, where it can be absorbed directly by the animal. This mechanism effectively upgrades the quality of the protein the animal derives from the feed. At high concentrations, however, tannins can reduce palatability and overall digestibility. The review found that other anti-nutritional compounds, including oxalates and saponins, are present only at low levels in the studies examined, and no toxicity has been reported at the dietary inclusion rates evaluated to date. Post-harvest processing such as ensiling or drying can further reduce these compounds, and fermentation during ensiling appears to mellow bitter-tasting secondary metabolites while stabilising key nutrients, which in turn increases voluntary intake.

The animal performance data are where ramie’s potential becomes tangible. In sheep and goats, voluntary dry matter intake of ramie-based diets has generally ranged between 2.5 and 3.5 percent of body weight in the reviewed trials, comparable to lucerne-based diets and typically higher than diets dominated by tropical grasses such as Napier grass. Partial replacement of conventional roughage with ramie increased average daily gain in growing goats by 12 to 18 percent, while lambs fed diets containing up to 30 percent ramie achieved daily gains of 160 to 180 grams. In dairy goats, replacing 25 percent of the forage component with ramie raised milk yield by 8 to 10 percent and increased concentrations of milk protein and fat. There is a clear ceiling, though: inclusion rates above 40 percent have been associated with off-flavours in milk, likely caused by the transfer of specific phenolic compounds into the milk fat, and growth performance declined in goats when dried whole-plant ramie replaced more than 35 percent of dietary alfalfa.

Beyond growth and milk, ramie appears to influence rumen function and animal health in subtler ways. Feeding studies have reported that ramie helps maintain rumen pH within the normal physiological range and increases total volatile fatty acid concentrations, the primary energy currency of the ruminant host. Blood metabolite profiles in the reviewed trials remained normal, suggesting no adverse health effects at moderate inclusion levels. Emerging in vitro work adds an environmental dimension: ramie silage lowered methane production relative to corn silage in fermentation studies, although fibre degradability declined once its inclusion exceeded 40 percent of dietary dry matter. The leaves are also rich in bioactive compounds with documented antibacterial, antiviral, antioxidant and anti-inflammatory activities. Evidence from non-ruminant species supports these functional effects, with ramie leaf powder improving antioxidant status and growth in ducks, enhancing yolk colour and fatty acid profile in laying hens, and improving carcass traits in pigs at low inclusion levels.

The review is candid about the crop’s vulnerabilities and the gaps in the evidence base. Ramie remains susceptible to economically significant pests and diseases, including the ramie moth, stem borers, anthracnose and root rot, and current control strategies lean heavily on chemical inputs that risk toxic residues in forage and inflate production costs. Forage-specific cultivars bred for resistance and quality are scarce, since breeding programmes have historically targeted fibre traits. Perhaps the most striking caveat concerns the plant’s remarkable ability to hyperaccumulate heavy metals such as zinc, cadmium and lead from contaminated soils. While this makes ramie a powerful tool for cleaning up mine sites and polluted land, it creates a serious toxicological hazard if such biomass enters the feed chain. The authors stress that ramie grown for phytoremediation must be strictly excluded from livestock diets, and that a clear separation must be maintained between remediation plantings and forage production on uncontaminated ground.

The authors conclude that ramie’s combination of agronomic adaptability, nutritional quality and multifunctionality makes it a promising candidate for climate-smart livestock systems, but they are equally clear that the current literature is fragmented. Most studies have been conducted under controlled conditions or in limited geographic regions, long-term feeding trials under commercial conditions are lacking, and farm-level economic analyses and life-cycle assessments are almost entirely absent, preventing definitive recommendations for large-scale producers. Standardised guidance on nutrient management, harvesting intervals and dietary inclusion levels is needed to reduce the variability in forage quality that currently complicates year-round feeding strategies. The research roadmap the authors propose spans forage breeding programmes, mechanistic studies of rumen microbiome dynamics and methane mitigation, and rigorous sustainability accounting. If those gaps can be filled, an ancient fibre crop may find a new role at the intersection of animal nutrition and climate resilience, turning a plant once grown for cloth into a cornerstone of feed security for the world’s small ruminants.

Subject of Research: Ramie (Boehmeria nivea) as a high-protein forage crop for small ruminant nutrition and climate-resilient livestock production

Article Title: Boehmeria nivea (Ramie) as a high protein forage crop for small ruminants focusing on agronomic potential, nutritive value, and animal performance

Article References: Jejal, A., Saxena, A., Singh, M., Saraswat, P. K., Mondal, G., & Kumar, S. (2026). Boehmeria nivea (Ramie) as a high protein forage crop for small ruminants focusing on agronomic potential, nutritive value, and animal performance. Discover Plants, 3(1), Article 453. https://doi.org/10.1007/s44372-026-00928-y

Image Credits: AI Generated

DOI: 10.1007/s44372-026-00928-y

Keywords: ramie, Boehmeria nivea, forage crop, small ruminants, goats, sheep, crude protein, drought tolerance, rumen fermentation, climate-smart agriculture, animal performance, sustainable livestock

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 ruminant gastrointestinal tract is not a single environment but a series of specialized fermentation chambers, each hosting distinct microbial communities. The rumen, the primary anaerobic fermenter, is dominated by three core phyla: Bacteroidetes, Firmicutes, and Proteobacteria. These organisms secrete cellulases and hemicellulases that dismantle crude fiber, generating volatile fatty acids, chiefly acetate, propionate, and butyrate, which together supply the majority of the animal’s energy. Propionate is funneled into gluconeogenesis to fuel muscle tissue, while acetate feeds lipid synthesis and butyrate powers epithelial metabolism. Rumen microbes also degrade feed proteins and rebuild them into microbial crude protein, which the host digests downstream as its principal source of amino acids for muscle growth.

Downstream compartments carry out complementary tasks. Bifidobacterium and Lactobacillus in the small intestine participate in protein and amino acid degradation, while Bacteroides and Clostridium in the large intestine finish the job of cellulose breakdown. Some strains synthesize B vitamins, including vitamin B12, which participates in fatty acid beta-oxidation and stimulates propionate production by the rumen bacterium Xylanibacter ruminicola. Crucially, microbial volatile fatty acids activate the G protein-coupled receptors GPR41 and GPR43 on intestinal epithelial cells, promoting tight junction proteins such as Claudin-1 and Occludin and dampening NF-kappaB signaling. A healthy, anti-inflammatory gut environment is thus the metabolic foundation upon which marbling and favorable fatty acid profiles are built.

Meat color, one of the first attributes a shopper judges, hinges on the content and oxidation state of myoglobin, whose synthesis depends on iron, copper, and zinc. The review describes how lactic acid bacteria and bifidobacteria lower intestinal pH, converting insoluble feed iron into absorbable forms, while certain microbes produce iron-scavenging carriers and modulate the host’s iron transporters DMT1 and FPN1. Oxidative stability matters just as much: in sheep, aflatoxin exposure disrupts the microbiota, depletes Clostridium butyricum, raises oxidative stress markers, and measurably reduces redness values. Conversely, gut bacteria that synthesize antioxidants such as vitamin E and glutathione correlate strongly with better color scores, a relationship reported with an R-squared of 0.68, and can extend the window of premium color by two to three days. Butyrate reinforces this defense by activating the Nrf2 pathway, upregulating endogenous antioxidant enzymes including superoxide dismutase and glutathione peroxidase.

Tenderness and juiciness trace back to intramuscular fat, muscle fiber composition, and water retention, all of which respond to microbial signaling. Butyrate activates the peroxisome proliferator-activated receptor gamma, or PPARgamma, pathway, steering adipocyte differentiation and boosting intramuscular fat deposition; sheep carrying more butyrate-producing bacteria show higher marbling. Water-holding capacity is likewise microbially influenced, with ruminal butyrate upregulating myosin expression in muscle cells, stabilizing cellular osmotic pressure, and reducing drip loss. On the flavor front, rumen anaerobes mediate biohydrogenation that governs fatty acid saturation, and greater anaerobic diversity enhances conjugated linoleic acid content, a functional fatty acid prized for both health properties and taste. Acetate upregulates acetyl-CoA carboxylase and fatty acid synthase to promote lipid synthesis, while propionate inhibits fatty acid synthase, trimming fat deposition in bovine muscle and subcutaneous adipocytes.

At the molecular level, short-chain fatty acids act as signaling molecules that reach skeletal muscle through the portal vein and peripheral circulation, binding GPR41 and GPR43 and triggering two core cascades: AMPK-PGC-1alpha and the PPAR family. Activated AMPK promotes fatty acid uptake and oxidation while curbing lipogenesis, and PGC-1alpha, the master regulator of mitochondrial biogenesis, drives the conversion of fast-twitch fibers toward oxidative, slow-twitch Type I fibers, which in turn improves color stability and water-holding capacity. PPARalpha promotes lipid oxidation, PPARgamma supports intramuscular fat and oxidative fiber formation, and PPARdelta, upregulated by butyrate, engages in reciprocal activation with AMPK, forming a positive feedback loop that balances fiber type and fat content, the twin determinants of tenderness, flavor, and nutritional value.

What elevates this review beyond mechanism is its catalog of practical interventions. Dietary strategy remains the first lever: grass-fed systems enrich fiber-degrading microbes such as Fibrobacter and the Christensenellaceae R-7 group, raising omega-3 polyunsaturated fatty acids, vitamin E, and antioxidants in leaner cuts, while grain-fed systems boost Prevotella and intramuscular fat, producing more tender, juicy meat at the cost of a higher saturated fat fraction. Phased feeding that combines both, keeping roughage above fifteen percent to avoid ruminal acidosis, has been shown to optimize outcomes; a concentrate-to-roughage ratio of 70:30 improved slaughter performance and tenderness in Tibetan sheep, whereas an 80:20 ratio increased drip loss. Plant-derived compounds add another layer, with pine nut essential oil reducing intestinal methane emissions and combined inhibitors suppressing methane production by up to 99.2 percent while increasing volatile fatty acid output.

Probiotics and enzyme inhibitors represent the precision end of the spectrum. Bacteroides distasonis F4, a novel strain isolated from calf rumen and validated by whole-genome sequencing, reshapes microbial community structure and elevates short-chain fatty acid production. Supplementation with Lactobacillus at one percent of the diet in Sunit sheep promoted muscle fiber type conversion via the AMPK pathway and improved meat quality. On the inhibitor side, researchers at the Chinese Academy of Agricultural Sciences used metagenomics to identify dominant urease genes in the bovine rumen, traced them to a novel genus within the Acinetobacteraceae family, and developed epiberberine, a plant-derived urease inhibitor that curbs ammonia waste and improves nitrogen use, lean meat yield, and flavor. Methanogenesis can be targeted directly through 2-bromoethanesulfonate, a specific inhibitor of methyl-coenzyme M reductase, which redirects hydrogen flux from methane toward propionate, raising feed conversion efficiency, muscle glycogen reserves, and intramuscular fat deposition.

Husbandry and stress management complete the picture. Exercise promotes propionate-producing Bacteroidetes and improves insulin sensitivity and dressing percentage, though excessive exertion can toughen meat, demanding carefully calibrated protocols. Transport and crowding stress destabilize the gut microbiota, driving abnormal muscle pH and water loss; shortening journeys and administering gamma-aminobutyric acid or probiotic complexes alleviates dysbiosis and preserves color and moisture. The authors also flag the field’s open problems: host-specificity complicates universal rules, multi-omics data integration and causal validation remain immature, and long-term safety assessments, probiotic stability, and precise delivery of metabolic modulators still constrain industrial adoption. Vigilance against antibiotic resistance and pathogen transfer is likewise essential.

The trajectory ahead is unmistakably interdisciplinary. Single-cell sequencing and spatial metabolomics promise to map microbe-to-muscle signaling with unprecedented resolution, while synthetic biology could engineer functional strains and structural biology could yield a new generation of natural inhibitors. Internet-of-Things platforms for dynamic microbial monitoring and precision feeding, combined with artificial intelligence-driven network analysis, point toward personalized interventions tailored to species, breed, and production environment. If the promise holds, the same microbes that ferment grass in the rumen could simultaneously deliver tastier steaks, leaner lambs, lower methane footprints, and more sustainable farms, a convergence of consumer pleasure and planetary benefit that few other levers in animal agriculture can claim.

Subject of Research: Mechanisms by which gut microbiota regulate meat quality in ruminants and microbiota-targeted intervention strategies

Article Title: Gut microbiota and meat quality in ruminants: a review of mechanisms and microbiota-targeted interventions

Article References: Jia, Y., Liu, K.-L., & Huang, S.-C. (2026). Gut microbiota and meat quality in ruminants: a review of mechanisms and microbiota-targeted interventions. Food Science of Animal Resources, 46(1), Article 79. https://doi.org/10.1007/s44463-026-00095-4

Image Credits: AI Generated

DOI: 10.1007/s44463-026-00095-4

Keywords: gut microbiota, ruminants, meat quality, short-chain fatty acids, intramuscular fat, probiotics, enzyme inhibitors, methane reduction, PPAR signaling, AMPK pathway, fatty acid metabolism, sustainable livestock