What Do Sheep Eat in Australia?

Understanding what sheep eat — and what they should eat — is fundamental to running a productive, healthy flock. Nutrition drives everything: reproductive performance, wool growth, lamb growth rates, immune function, body condition, and longevity. Get the feeding right, and your sheep will reward you. Get it wrong, and no amount of veterinary treatment or genetics will compensate.

This guide covers the full picture of sheep nutrition in Australia: what sheep naturally eat on pasture, how their digestive system works, the role of supplements, and how to match nutrition to the different stages of the sheep's production cycle.

How Sheep Digest Food: The Ruminant Advantage

Sheep are ruminants, which means they have a specialised four-compartment stomach that allows them to break down fibrous plant material that would be indigestible to non-ruminants.

The four compartments are:

1. Rumen — the largest compartment, a fermentation vat containing billions of microorganisms (bacteria, protozoa, fungi) that break down fibre through fermentation. This is where cellulose from grasses and hay is converted into volatile fatty acids (VFAs) — the sheep's primary energy source.

2. Reticulum — closely associated with the rumen; helps sort ingested material and passes larger particles back for re-chewing (rumination, or "chewing the cud").

3. Omasum — absorbs water and minerals from the digesta before it moves to the true stomach.

4. Abomasum — the "true stomach," functioning like a simple stomach, producing acid and enzymes to digest protein and fine particles.

This digestive system gives sheep remarkable ability to extract nutrition from fibrous, low-quality feeds — but it also imposes constraints. Rumen microbes take time to adjust to new feeds; sudden diet changes can cause acidosis or other disorders. Transition to new feeds (particularly grain) must be done gradually.

What Sheep Eat in the Wild and on Pasture

In their natural state, sheep are selective grazers that prefer certain plant types and parts of plants. In Australia, sheep graze on:

Native Pastures

Much of Australia's pastoral estate is covered by native grass and shrub communities. Common native species grazed by sheep include:

• Wallaby grasses (Austrodanthonia spp.) — palatable and nutritious when green
• Red grass (Bothriochloa macra) — common in eastern Australia
• Spear grasses (Austrostipa spp.) — less palatable but grazed in early growth stages
• Mitchell grass (Astrebla spp.) — highly productive in western Queensland and NT
• Saltbush (Atriplex spp.) — important feed in arid zones; highly nutritious despite high salt content
• Bluebush (Maireana spp.) — valuable drought feed in arid SA and WA
• Native herbs and forbs — often highly nutritious and preferentially grazed

The nutritional quality of native pastures varies enormously with season, rainfall, and soil type. Green native grasses during active growth can be highly nutritious; the same grasses standing dry and bleached in summer provide little beyond bulk fibre.

Improved Pastures

Most intensive sheep farming regions in Australia rely on sown improved pastures:

• Annual ryegrass (Lolium rigidum) — prolific and palatable, but beware ryegrass staggers (endophyte toxicity)
• Perennial ryegrass (Lolium perenne) — higher-yielding, used in higher-rainfall areas
• Subterranean clover (Trifolium subterraneum) — the backbone of southern Australian mixed farming; fixes nitrogen and is highly nutritious
• White clover (Trifolium repens) — very nutritious, used in high-rainfall zones
• Phalaris (Phalaris aquatica) — persistent perennial grass in medium-rainfall areas; can cause phalaris staggers if not managed
• Lucerne/Alfalfa (Medicago sativa) — extremely nutritious; high protein (18–22% CP); can cause bloat if grazed fresh without hay in the system
• Cocksfoot (Dactylis glomerata) — palatable perennial grass in cooler zones
• Tall fescue — persistent and drought-tolerant; variable palatability
• Medics (Medicago spp.) — annual legumes important in the southern wheat belt of WA and SA

Crops and Stubbles

In mixed farming districts, sheep play an important role in utilising:

• Cereal stubbles (wheat, barley, oats) after harvest — provide fibre and some grain; quality varies with rainfall and harvest losses
• Canola stubbles — can be high in sulphur; don't graze exclusively
• Crop failures — failed cereal or canola crops may be grazed off
• Standing fodder crops — oats, barley, forage sorghum, turnips, rape, and kale grown specifically for winter grazing

Key Nutrients Sheep Need

Energy

Energy is the most commonly limiting nutrient for Australian sheep. It is measured as Metabolisable Energy (ME) in megajoules per kilogram of dry matter (MJ ME/kg DM).

• Maintenance: A 50 kg Merino ewe requires approximately 7–8 MJ ME/day just to maintain body weight
• Late pregnancy (twins): 14–16 MJ ME/day
• Peak lactation: 18–22 MJ ME/day
• Growing lamb: 12–15 MJ ME/day depending on target growth rate

High-quality pasture and legumes typically provide 10–12 MJ ME/kg DM. Dry summer grass may provide only 6–8 MJ ME/kg DM. Grain typically provides 12–14 MJ ME/kg DM.

Protein

Protein is measured as Crude Protein (CP) as a percentage of dry matter. Sheep need adequate dietary protein for: - Body tissue maintenance and repair - Wool production (wool is almost entirely protein — sulphur-containing amino acids, particularly methionine and cysteine) - Milk production - Foetal growth

Requirements by class: - Dry ewes/wethers: 8–9% CP - Pregnant ewes: 10–14% CP - Lactating ewes: 15–18% CP - Growing lambs: 16–20% CP

Green pasture and legumes typically exceed protein requirements. Dry summer grass (as low as 4–6% CP) is often protein-deficient.

Fibre

Adequate fibre is essential for rumen function. Sheep should always have access to some form of long fibre (pasture, hay, silage) to maintain rumen motility and prevent acidosis. When feeding grain, ensure fibre intake is maintained.

Minimum effective fibre level: approximately 25–30% neutral detergent fibre (NDF) in the total diet.

Minerals

Key minerals for Australian sheep:

• Calcium and Phosphorus: Essential for bone development, milk production, and general metabolism. Ratio important (Ca:P should be approximately 2:1). High-grain diets can invert this ratio.
• Magnesium: Deficiency causes grass tetany (hypomagnesaemia); most common in lush spring pastures. Supplement with causmag (magnesium oxide) in high-risk periods.
• Sodium (salt): Often deficient in pasture-only diets. Offer loose salt or lick blocks.
• Sulphur: Required for wool production (wool is 3–4% sulphur). High-protein diets usually supply adequate sulphur; if not, add elemental sulphur to supplement mix.
• Copper: Deficiency causes swayback (enzootic ataxia) in lambs; excess copper causes fatal hepatic necrosis — Merinos are particularly susceptible. Don't feed copper supplements unless deficiency is confirmed.
• Zinc: Deficiency causes reduced fleece weight and poor wound healing.

Trace Elements

• Selenium: Deficiency is widespread in Australia (particularly high-rainfall granitic soils of WA, Vic, SA). Causes white muscle disease in lambs and ill-thrift. Supplement via selenium injection to ewes pre-lambing, or selenium-fortified supplements.
• Iodine: Deficiency causes goitre and lamb losses, particularly in high-rainfall areas. Supplement ewes pre-lambing with iodised oil injection.
• Cobalt: Sheep need cobalt to synthesise Vitamin B12 in the rumen. Deficiency causes "coast disease" — ill-thrift, anaemia, and wasting. Common in coastal WA, SA, and southern Vic. Supplement with cobalt pellets (ruminal boluses) or cobalt-containing fertilisers.
• Copper: As above — deficiency and toxicity are both problems. Test before supplementing.

Vitamins

• Vitamin A: Synthesised from beta-carotene in green pasture. Deficiency possible in sheep on dry feed for extended periods. Night blindness and reproductive failure are symptoms.
• Vitamin D: Synthesised from sunlight. Deficiency is rare in outdoor animals.
• Vitamin E: Works with selenium as an antioxidant; relevant to white muscle disease prevention in lambs.
• Vitamin B12: Synthesised in the rumen from cobalt. See cobalt above.

Supplementary Feeding

When pasture is inadequate — in drought, late pregnancy, or intensive production systems — supplementary feeding bridges the gap.

Hay

Hay is the most commonly used supplement in Australia. Types and quality:

Test your hay with a feed analysis before feeding it — colour and smell are poor guides to nutritional quality.

Grain

Grain is a high-energy supplement well suited to lifting ewe condition in late pregnancy and finishing lambs. Common grain types:

Grain introduction: Never introduce sheep directly onto high grain without a transition period. Start with 100–150g/head/day and increase over 2–3 weeks to the target rate. Acidosis and polioencephalomalacia (thiamine deficiency from grain feeding) are risks with sudden or excessive grain feeding.

Commercial Pellets and Supplements

A range of commercial sheep pellets and lick blocks are available, formulated for specific purposes: - High-energy pellets for late pregnancy and finishing - Protein pellets or loose lick containing urea (a non-protein nitrogen source — use with care; urea toxicity can occur if over-consumed) - Mineral and vitamin supplements in block, loose, or injectable form - Emergency drought rations — complete feeds with fibre, energy, protein, and minerals balanced

Water

Water is technically a nutrient — and the most critical one. Sheep can tolerate mild dehydration, but water restriction severely limits dry matter intake and productivity.

Daily water requirements: - Dry sheep (mild weather): 2–4 litres/day - Lactating ewes (mild weather): 4–6 litres/day - All classes (hot weather, > 35°C): Double to triple normal requirements - Sheep on dry feed: Higher water intake needed than on green pasture (green grass is 70–80% water)

Water quality matters. Salt concentration above 4,000 mg/L total dissolved solids (TDS) can affect sheep productivity; above 10,000 mg/L is dangerous. Test bore and dam water quality if in doubt.

Feeding Sheep Through the Production Cycle

Maintenance (Dry Season, Non-Pregnant, Non-Lactating)

Most demanding in terms of nutritional management during summer in southern Australia, when pastures are dry and hot.

• Dry sheep can maintain body condition on 6–7 MJ ME/day
• If pasture quality drops below this, body condition will fall
• Providing access to high-quality hay or modest grain supplementation prevents excessive condition loss

Flushing (Pre-Joining)

As discussed in the lambing guide, improving ewe nutrition for 3–6 weeks before joining increases ovulation rate and conception. Target BCS 3.0–3.5 at joining.

Early Pregnancy

Nutritional requirements are moderate in early pregnancy. Focus on maintaining condition rather than intensive supplementation.

Late Pregnancy (Final 6–8 Weeks)

The most critical feeding period. Foetal growth is rapid; rumen space is compressed by multiple foetuses, reducing dry matter intake capacity. Energy demand exceeds what many ewes can consume from pasture alone.

• Supplement with 200–400g grain/head/day for multiples
• Provide high-quality hay alongside grain
• Monitor for pregnancy toxaemia in twin- and triplet-bearing ewes

Lactation

Peak nutritional demand for the ewe. A well-fed ewe produces enough milk to sustain 20–40g/day growth in her lambs in the first 6–8 weeks.

• Provide the best available pasture to lactating ewes
• Supplement with grain (200–400g/head/day) if pasture is inadequate
• Ensure adequate water at all times

Growing Lambs and Weaners

Post-weaning is a critical period. Weaners (weaned lambs) are small, have high growth requirements, and are particularly susceptible to worm burdens and nutritional stress.

• Offer weaners the best-quality pasture or supplement with grain
• Target 150–250g/day liveweight gain
• Provide 15–20% CP in the diet for optimal wool and muscle growth

Common Nutritional Problems in Australian Sheep

Practical Feeding Tips for Australian Sheep Farmers

1. Know your pasture quality. Test pasture dry matter, ME, and protein seasonally. You can't manage what you don't measure.

2. Feed to the stage of production. A dry ewe in summer has vastly different needs from a twin-bearing ewe in late pregnancy. Match your supplementation to the animal's actual requirements.

3. Body condition score regularly. The body of the sheep is the best indicator of whether nutrition is adequate. Score at joining, mid-pregnancy, lambing, and weaning.

4. Introduce new feeds slowly. Any significant dietary change — grain, new pasture, new hay — should be introduced over 10–14 days minimum.

5. Never run out of water. Check troughs and dams daily in summer. Dehydration is immediately production-limiting and potentially fatal.

6. Don't over-supplement. Copper toxicity, urea toxicity, and over-fat ewes are all consequences of excessive feeding. More is not always better.

7. Think ahead. Good sheep nutrition is planned in advance, not reacted to in a crisis. Monitor pasture covers, plan your supplementary feed budget, and act before body condition slips.

Sheep are remarkable converters of marginal feed resources into wool, meat, and milk. Understand their nutritional needs, match their feed supply to those needs through the production year, and your flock will perform to its genetic potential.