Ethiopia forage study finds trees hold protein through the dry season
A field and laboratory study in southern Ethiopia has identified a practical seasonal division of labour among indigenous cattle forages: grasses supplied most of the biomass, while shrubs and fodder trees retained more protein and digestibility during the dry season. The peer-reviewed study was published on 21 October 2026 in Pastoralism: Research, Policy and Practice.
Researchers surveyed 371 pastoral and agro-pastoral households across 12 kebeles in the Dasenech, Nyangatom, Salamago and Kolume districts. They sampled 20 locally used forage species across wet and dry seasons, measured herbaceous biomass in 260 one-square-metre quadrats, and analysed crude protein, fibre, ash and in-vitro digestibility.
The central finding is complementarity, not a single superior forage
Para grass produced the largest measured dry-matter yield at 11.2 tonnes per hectare, followed by buffel grass at 10.7 tonnes and switchgrass at 9.7 tonnes. Those figures show why perennial grasses remain the bulk-energy base of cattle diets in the study area.
But biomass alone did not describe feed value. During dry-season sampling, the nine shrubs and fodder trees in the study averaged about 16.5% crude protein and 66.5% in-vitro dry-matter digestibility. The three grasses with separate wet- and dry-season measurements averaged about 7.5% crude protein and 56.5% digestibility in the dry season.
That makes the browse average roughly 2.2 times the grass average for crude protein and about ten percentage points higher for in-vitro dry-matter digestibility. These Agrilinkage calculations use the published species values and are descriptive averages, not treatment effects.
Forage measure | Published result | What it implies |
Highest biomass | Para grass: 11.2 ± 0.7 t DM/ha | Large contribution to basal feed quantity |
Highest dry-season crude protein | Moringa stenopetala: 23.5% DM | Potential protein-rich supplement, not a complete ration by itself |
Highest dry-season digestibility | Moringa stenopetala: 77.7% IVDMD | Strong laboratory digestibility result requiring animal-level validation |
Dry-season browse average | About 16.5% crude protein; 66.5% IVDMD | Quality buffer when grasses mature and lose nutritive value |
Dry-season grass average | About 7.5% crude protein; 56.5% IVDMD | Bulk remains available, but supplementation becomes more important |
Moringa stood out, but the lower-yielding tree cannot replace grass biomass
Moringa stenopetala recorded 23.5% crude protein, 77.7% in-vitro dry-matter digestibility and 74.5% in-vitro organic-matter digestibility in the dry season. By comparison, dry-season crude protein was 7.5% in buffel grass, 6.6% in smut grass and 8.3% in switchgrass.
The apparent nutritional advantage needs the yield context. The study estimated only 2.2 tonnes per hectare of edible moringa leaves and tender twigs, the lowest dry-matter yield among the measured species, compared with 11.2 tonnes for para grass. The figures are not directly interchangeable because woody-plant yield counted edible browse rather than total above-ground mass, but they reinforce the study's wider conclusion: grass supplies volume; selected browse supplies concentrated quality.
Other dry-season browse also performed well. Grewia bicolor contained 19.9% crude protein with 69.1% in-vitro dry-matter digestibility. Ficus sycomorus measured 16.9% protein and 71.5% digestibility. Celtis ehrenbergiana, Cadaba farinosa and Acalypha fruticosa remained between 14.5% and 16.3% protein.
The seasonal availability pattern strengthens the feeding case
Annual grasses were rated highly available in the wet season but low in the dry season. Several woody species followed the opposite pattern: Celtis, Grewia, Cadaba, Vachellia, moringa and sycamore fig received high or very high dry-season availability scores. Perennial grasses such as buffel grass and switchgrass persisted moderately into the early dry season.
This creates a feasible calendar rather than a simple substitution. Wet-season grass and legume growth can build bulk and protein. Persistent perennial grasses carry part of the base ration into drier months. Browse then becomes more valuable as herbaceous forage senesces, crude protein falls and fibre rises.
The protein-to-digestibility relationship was strong across the tested samples. Crude protein correlated positively with in-vitro dry-matter digestibility at r = 0.81 and with organic-matter digestibility at r = 0.83. Neutral-detergent fibre correlated negatively with both measures. These relationships are consistent with established ruminant nutrition, but the useful contribution here is species- and season-specific evidence for the Omo–Woito production systems.
What the study does—and does not—prove
The work combines household knowledge, botanical identification, field biomass measurements and laboratory analysis. Samples were tested in triplicate, and voucher specimens were deposited at the Arba Minch University Herbarium. That makes it more informative than a perception survey alone.
It was not, however, a controlled cattle feeding trial. The researchers did not measure live-weight gain, milk output, fertility, animal health, intake or farmer profit under diets containing the different plants. In-vitro digestibility simulates digestion in the laboratory; it does not guarantee the same response in a herd.
The study also did not measure tannins, saponins, alkaloids or other anti-nutritional compounds that can alter palatability and nutrient use. Soil conditions and grazing intensity were not included as explanatory variables. Seasonal availability scores partly relied on indigenous knowledge and field observation, and the sampling covered one study period rather than multiple rainfall years.
Those limitations matter especially before promoting a tree as a feed intervention. Safe inclusion rates, harvesting pressure, labour requirements, propagation, land tenure and competition with other uses all need testing. A nutritionally promising leaf can still be impractical or harmful if ration balance and secondary compounds are ignored.
The practical next step is a ration and management trial
The strongest follow-on experiment would compare locally realistic dry-season rations: grass alone, grass plus one browse species, and grass plus mixed browse. It should measure voluntary intake, weight change or milk yield, feed conversion, animal health, labour, cost per unit of output and the regeneration of harvested woody plants.
Multi-year monitoring is equally important. A species that remains available in one dry season may respond differently under consecutive droughts, heavier grazing or changed river flows. Measuring soil moisture, rainfall, grazing pressure and plant recovery would show whether the proposed feed buffer is ecologically sustainable.
Why it matters beyond one river basin
The study should not be generalized automatically to all Ethiopian or African drylands. The species mix, soils, rainfall, grazing institutions and household strategies are local. But its analytical framework is transferable: evaluate feed resources simultaneously for quantity, nutrient quality, seasonal availability and management cost.
That matters because drought feeding is often treated as a search for one miracle crop. The Omo–Woito results point instead to a portfolio: high-yield grasses for basal energy and fibre, legumes where moisture permits, and carefully managed shrubs and trees as protein-rich dry-season reserves. The value lies in the combination—and in testing whether that combination improves real animal and household outcomes.
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