Feeding Sheep in Australia

Sheep are ruminants — they have a four-chambered stomach and rely on microbial fermentation in the rumen to extract energy and protein from fibrous plant material. Understanding this basic biology makes the practical feeding advice that follows make more sense, because many of the rules of sheep nutrition — particularly around rate of diet change, roughage requirements, and the relationship between fermentable carbohydrate and rumen health — flow directly from the way the rumen works.

The rumen functions as a large fermentation vat, populated by billions of bacteria, protozoa, and fungi that are adapted to whatever the animal has been eating. Change the diet suddenly and you disrupt this population — the organisms suited to the old diet die off before those suited to the new diet have time to proliferate. The result is reduced fermentation efficiency, digestive upset, and in severe cases, lactic acidosis (grain poisoning). This is why all diet transitions — from dry pasture to green feed, from pasture to grain, from one grain type to another — must be made gradually over ten to fourteen days minimum.

The rumen also generates significant metabolic heat as a byproduct of fermentation. This has practical implications: increasing roughage intake before cold weather provides additional thermogenic capacity; conversely, a sheep in heat stress reduces feed intake to reduce metabolic heat load, which compounds the effects of heat stress on production. Understanding the rumen as a heat-generating engine helps explain many otherwise puzzling seasonal nutrition observations.

The nutrient requirements of sheep are typically expressed in terms of dry matter intake (the amount of feed consumed on a moisture-free basis, typically 3 to 4% of bodyweight per day for actively growing pasture conditions), metabolisable energy (ME, measured in megajoules per kilogram of dry matter — a 70kg ewe at maintenance needs approximately 9 to 11 MJ/day), and crude protein (CP — the total nitrogen content of the diet expressed as equivalent protein, with minimum requirements varying from 6 to 8% CP for dry non-productive ewes to 14 to 16% CP for peak-lactation ewes nursing twins). These numbers become practical when you know the nutritional composition of your feeds — and the gap between what your current feed provides and what your animals need is the supplementation requirement.

Pasture is the foundation of almost every Australian sheep enterprise, and the ability to accurately assess pasture quantity and quality is one of the most valuable — and most underutilised — skills in sheep production. Many producers manage by feel and observation, which works reasonably well in average years but fails badly when conditions are unusual. Systematic pasture assessment removes the guesswork from one of the most important production decisions you will make.

Pasture dry matter (DM) availability is typically measured as kilograms per hectare. The rising plate meter is the most practical tool for regular on-farm measurement — it is quick to use, durable, and provides reliable relative readings once calibrated against known cuts for your specific pasture types. Most sheep pastures need to maintain at least 800 to 1,200 kg DM/ha to allow adequate selective intake by grazing animals (below this threshold, sheep spend so much energy searching for adequate feed that production suffers even if the total available dry matter would theoretically meet their requirements). Above 2,500 kg DM/ha, quality begins to decline as proportion of dead material and older growth increases.

Pasture quality — particularly energy and protein content — changes dramatically through the season in ways that are not always visible. Green, leafy, actively growing temperate pastures (ryegrass and clover) typically have an ME of 10 to 12 MJ/kg DM and a CP of 18 to 22% — well above the requirements of all but peak-lactation ewes. The same paddock in January, brown and dormant after summer heat, may have an ME of 6 to 7 MJ/kg DM and CP of 4 to 6% — well below the maintenance requirements of any productive animal. This seasonal quality collapse is the most common cause of poor reproductive performance, weight loss, and increased disease susceptibility in Australian sheep enterprise, and it is entirely predictable and manageable with adequate preparation.

Tropical pasture grasses — buffel grass, Mitchell grass, para grass, Rhodes grass — present a specific challenge because even green, actively growing material from most tropical grass species is significantly lower in energy and protein than temperate legume-grass pastures. ME of 7 to 9 MJ/kg DM and CP of 6 to 10% are typical for tropical grasses in active growth, with quality declining sharply as the season advances and seed heads develop. Producers in tropical and subtropical regions who manage sheep on grass-dominant pastures need to factor this baseline quality difference into their supplementation planning.

Legumes in the pasture mix substantially improve nutritional quality. Subterranean clover in southern Australia, white clover in irrigated situations, and tropical legumes like stylosanthes and lablab in northern areas all lift both energy and protein content of the grazing diet significantly. Maintaining legume content above 20 to 30% of the pasture composition is a worthwhile agronomic goal for any sheep enterprise. Soil pH, phosphorus levels, and correct rhizobium inoculation at establishment are the primary determinants of legume persistence — soil testing and targeted fertilisation pay for themselves in improved pasture productivity.

Rotational grazing — dividing available area into multiple paddocks and moving stock regularly — improves pasture utilisation, maintains pasture quality at higher levels for longer through the season, and importantly for sheep health, allows parasite larval die-off during the paddock rest period. The minimum rest period for meaningful larval reduction is six weeks in warm conditions; longer in cooler weather. Setting up a rotational grazing system requires investment in fencing but typically pays for itself in improved carrying capacity and reduced drench requirements within two to three years.

Hay is the primary supplementary roughage for Australian sheep and the nutritional bridge across the gap between what pasture provides and what animals require. The range in quality between the best and worst hay available on the Australian market is enormous — a difference that translates directly to production outcomes when hay forms a significant part of the ration. Buying hay without understanding what you are getting is one of the most common and expensive nutritional mistakes in sheep management.

Lucerne hay is the highest-quality conventional hay available in Australia for sheep. High in protein (18 to 22% CP) and with reasonable energy (8 to 10 MJ ME/kg DM), it is the standard recommendation for ewes in late pregnancy, peak lactation, and for weaner lambs needing high-protein diets to support rapid growth. It is more expensive than grass hay and in some situations creates calcium:phosphorus imbalance issues if fed exclusively, but its nutritional superiority for high-demand classes of sheep is clear. When buying lucerne hay, assess: colour (should be green, not yellow or bleached), leaf retention (leaves contain most of the protein — shattered leaves indicate poor handling or storage), smell (fresh and slightly sweet — never musty), and cutting (early-cut, pre-bloom hay is significantly higher in quality than late-cut, mature-stem hay).

Cereal hays — oaten, wheaten, and barley hay — are the backbone of supplementary feeding for most southern Australian sheep enterprises. Quality varies enormously by cutting date and season. Oaten hay cut at the soft-dough stage (the most common and typically the best commercial buying option) has an ME of 8 to 9.5 MJ/kg DM and a CP of 7 to 10% — adequate for dry ewes and growing lambs with protein supplementation, but insufficient alone for peak-demand animals. Wheaten hay is similar in composition to oaten hay. Barley hay tends to be slightly lower in digestibility due to higher silica content and is less palatable to sheep.

Prairie hay and native grass hays are common in some Australian regions and range from reasonable quality (when cut early from improved native species) to poor quality (late-cut, mature native grasses). These are appropriate for dry adult maintenance but should not be relied on for productive animals without protein and energy supplementation.

Hay storage is critical to preserving the investment made in buying or producing it. Hay stored outside without cover loses 15 to 30% of its dry matter and significantly more of its nutritional value through the outer layers of each bale through weathering. Cover all hay storage wherever possible. If outside storage is unavoidable, orient stacks with the prevailing weather (stack so rain runs off ends rather than into the cut face of bales), keep bales off the ground on pallets, gravel or timber bearers, and accept that outer-layer losses will occur. Never feed mouldy hay — mycotoxins produced by mould contamination can cause reduced intake, reproductive losses, and acute illness.

Hay wastage at feeding is significant on most Australian sheep operations. Round bales fed on the ground to large mobs can result in 20 to 40% wastage through trampling and soiling. Hay rings reduce this to 5 to 10%. While hay rings require capital investment, the cost is recovered within a single season on any reasonable quantity of hay. Linear hay feeders along the fence are another effective option for small mobs in confined situations. Place hay feeders so that all animals in the mob can access them simultaneously without excessive competition — trough space of at least 300mm per adult sheep is the minimum for stress-free feeding.

Grain supplementation serves a specific and important role in sheep nutrition: providing concentrated energy (and in the case of legume grains, protein) when pasture and hay together cannot meet the demands of production. Grain is not a substitute for adequate roughage, should never be introduced rapidly to rumen-adapted animals, and requires more management attention than hay feeding — but used correctly, it is one of the most cost-effective production tools available.

Oats are the safest and most widely used grain for sheep in Australia. The grain has a high fibre hull that slows its fermentation rate in the rumen, reducing the risk of acidosis compared to barley or wheat. Oats have an ME of approximately 12 MJ/kg DM and a CP of 10 to 12% — adequate for most supplementary purposes. Sheep introduced to oats gradually can tolerate substantial quantities without digestive problems. They are a good starting grain for producers new to grain feeding.

Barley has higher energy density than oats (12.5 to 13 MJ ME/kg DM) and is widely used in feedlot and intensive supplementary programs. It ferments faster than oats and requires careful introduction — start at 100g per head per day and increase by no more than 50 to 100g per week. Rolled or steam-flaked barley has improved digestibility compared to whole grain. Barley is better value per unit of energy than oats in most seasons and is the most common grain used in large-scale sheep supplementation programs in southern Australia.

Lupins are exceptional for situations where protein supplementation is the primary need alongside moderate energy. At 28 to 34% crude protein and 14 MJ ME/kg DM, lupins are the highest-protein common grain available to Australian producers. They are extensively used in combination with oaten hay for late-pregnancy ewes and weaners in a ration that provides adequate roughage from hay and high protein and energy from lupins. Whole lupins are poorly digested — always feed split or crushed lupins to maximise digestibility. Lupins grown in Western Australia are available across Australia and are typically competitively priced on a protein per dollar basis.

Wheat is the highest-risk common grain for sheep — its rapid fermentation rate makes acidosis a real risk if introduction is too rapid or if animals gain access to unsecured wheat stores. Wheat has similar energy density to barley but is significantly more acidosis-prone and is best reserved for situations where other grains are unavailable or uneconomic. If feeding wheat, introduce extremely gradually and always ensure roughage is available before wheat is offered.

Purpose-formulated sheep pellets from commercial feed manufacturers provide a convenient, nutritionally consistent alternative to raw grain blending. Quality varies substantially between brands — always check the guaranteed specifications (minimum crude protein and minimum ME) on the product label. Sheep pellets are particularly useful for small operations without grain storage facilities and for situations requiring specific nutritional targets (late-pregnancy, lamb-finishing) that are difficult to achieve accurately with unformulated grain.

When feeding grain in groups, trough space is critical. Dominant animals will commandeer limited trough space and prevent subordinate animals from receiving their allocation. Provide minimum 300mm of linear trough space per adult sheep, and consider multiple feeding stations distributed around the yard to reduce competitive advantage for dominant animals. Monitor body condition individually (not just by mob averages) to identify animals that are missing out — they will be the lightest and the ones with the lowest BCS, and they are typically the animals most in need of supplementation.

Water is the most critical nutrient for sheep and the one most often underestimated in supply calculations. Sheep that are water-stressed reduce feed intake, lose production, and become more susceptible to heat stress and disease within 24 to 48 hours of restricted water access. Ewes in late pregnancy or peak lactation can begin losing lambs or milk production within a single day of inadequate water supply in hot conditions.

Daily water requirements for sheep vary substantially with temperature, production status, and diet type. A dry adult Merino ewe in moderate conditions (15 to 20°C) drinks approximately 3 to 4 litres per day. In summer heat (35°C plus), the same animal may drink 6 to 10 litres. A peak-lactation ewe nursing twins may drink 10 to 14 litres per day in summer. Lambs from two to twelve weeks of age drink surprisingly large quantities relative to their size, and adequate clean water access for young lambs is essential for good growth rates from early in life.

Sheep on dry feed (hay, stubble, grain) drink substantially more than those on fresh green pasture, which has high moisture content. Producers who move mobs onto stubble paddocks after harvest need to ensure water supply to the mob increases commensurately — water supply infrastructure designed for green-feed conditions will be inadequate for the same mob on dry summer stubble.

Water quality matters to sheep, though they are less sensitive to water quality variation than goats. The maximum tolerable salinity for sheep varies by production class: up to 5,000 mg/L total dissolved solids (TDS) for dry sheep, reducing to 3,000 mg/L for lambs and lactating ewes. Bore water across much of inland Australia exceeds these limits and requires blending with lower-salinity rainwater or treatment before use for the highest-demand classes. Algae bloom in summer troughs reduces palatability and intake — clean troughs at least weekly in summer and use shade cloth over tank openings to reduce light entry and algae growth.

Water infrastructure reliability is a genuine safety issue in Australian sheep management. A failed float valve or pump failure in summer can kill stock within 48 hours. Check all water points daily as part of the morning round; have backup equipment (spare float valves, a generator for solar-pump backup) on hand; and never assume a water source is flowing without visual confirmation. In remote areas or large properties, water infrastructure monitoring via telemetry or camera systems is increasingly affordable and worthwhile. A sheep producer who finds their mob has been without water for three days in a January heatwave is not having a management failure — they are having a catastrophe.

Australian soils and pastures have well-documented mineral deficiencies that differ significantly by region and that have direct production implications for sheep enterprises. Unlike generalised international sheep nutrition advice, Australian sheep producers need to understand the specific mineral profile of their district and manage accordingly.

Selenium deficiency is one of the most widespread and production-limiting mineral problems in Australian sheep. It is endemic across a large swathe of southeastern Australia, including most of Victoria, Tasmania, high-rainfall areas of South Australia, and significant parts of NSW and Queensland. Deficiency causes white muscle disease in lambs (a progressive degenerative muscle condition causing weakness and sudden death, typically in lambs from one to four months of age), poor wool quality, reduced reproductive performance in ewes, and impaired immune function across all classes. White muscle disease deaths in selenium-deficient areas are frequently attributed to other causes by producers who do not recognise the underlying deficiency — if you are losing young lambs to "sudden deaths" on your property, selenium status is the first thing to investigate.

Selenium supplementation options include: injection of sodium selenate (the most reliable option for known deficient areas — inject ewes four to six weeks pre-lambing and lambs at drenching time at four to six weeks of age); selenium-containing slow-release boluses (provide sustained release over several months); selenium-containing loose licks or blocks (less reliable because intake varies between individuals); and selenium-fortified drench products (convenient timing with routine drench events). Work with your vet or district veterinarian to establish the selenium status of your flock and the appropriate supplementation protocol for your region. Selenium is genuinely toxic in overdose — the margin between effective supplementation and toxicity is narrow, and supplementation without establishing deficiency first is not appropriate.

Copper deficiency occurs in coastal and high-rainfall areas of southeastern Australia and causes swayback (enzootic ataxia) in newborn lambs (a serious and often fatal neurological condition resulting from copper deficiency in the ewe during pregnancy) as well as reduced fleece quality and impaired immune function in adult sheep. The complication in sheep is that they are more susceptible to copper toxicity than cattle or goats — chronic copper accumulation causes sudden haemolytic crisis and death, and can be triggered by pastures that are high in copper (particularly those receiving copper-containing fungicide applications on nearby horticultural properties). Before supplementing copper in sheep, test liver copper levels in culled or recently dead animals to establish baseline status. Do not supplement copper in sheep without evidence of deficiency — the therapeutic window is narrower than for goats.

Iodine deficiency causes goitre and weak, stillborn lambs in deficient areas. Common in Tasmania, parts of coastal Victoria, and some NSW high-rainfall zones. Supplementation via iodised salt licks or pre-lambing injection is straightforward. If you are experiencing consistent lamb losses at birth of lambs that appear full-term but weak, with or without visible goitre, iodine deficiency is a strong diagnostic candidate.

Cobalt deficiency (which causes "pine" or "wasting" disease — progressive ill-thrift in young sheep) is significant in parts of Western Australia, South Australia, and Victoria on sandy or light soils. Cobalt is required for rumen microbe synthesis of vitamin B12 — deficient animals cannot produce adequate B12 for normal metabolism. Signs are gradual weight loss and ill-thrift in weaners that fail to respond to drenching or improved nutrition. A simple soil test will identify cobalt-deficient paddocks; supplementation is via cobalt-containing licks, cobalt sulfate in water, or cobalt/B12 injection.

A loose mineral lick or block appropriate for sheep (note that sheep require different mineral formulations to cattle, particularly around copper) should be available at all times as a baseline. This does not replace targeted supplementation of specific deficiencies identified by testing, but provides a safety net for minor deficiencies and allows animals to self-regulate intake of trace minerals to some extent. Replace blocks when they are consumed or become fouled — a block that animals are not using is either not needed or is not palatable.

The sheep production cycle has distinct nutritional phases with very different requirements. Matching feed supply to nutritional demand at each phase — rather than providing a uniform ration to all animals regardless of production status — is the single most impactful change most sheep producers can make to their nutritional management.

Joining preparation (flushing) begins four to six weeks before rams are introduced and is one of the most consistently high-return investments in sheep nutrition. The practice of increasing the nutritional plane of ewes before and during joining (flushing) improves ovulation rate, increases the proportion of ewes ovulating, and can lift scanning percentage by 10 to 20 percentage points above the result from ewes joined at maintenance. The effect is greatest in ewes that are at moderate body condition (BCS 2.5 to 3) — thin ewes and fat ewes both respond less strongly to flushing. The mechanism is the increase in blood glucose and insulin associated with a rising nutritional plane, which promotes follicular development and multiple ovulation. An extra 200 to 300 grams per head per day of grain or access to a fresh, high-quality pasture paddock achieves the effect — the specific feed is less important than the nutritional direction (rising).

Early pregnancy (first ten weeks, covering most of winter in autumn-joined flocks) has modest requirements above ewe maintenance. The developing embryos are very small in this period and the nutrient drain on the ewe is low. The risk at this stage is ewes that are losing body condition on inadequate winter pasture — embryo resorption rates increase in ewes that lose significant condition in early pregnancy. Maintain ewes at their joining BCS rather than allowing condition to fall during early pregnancy. A BCS of 2.5 to 3 entering mid-pregnancy is the minimum acceptable for a well-managed ewe flock.

Late pregnancy (final six weeks before lambing) is the highest-risk nutritional period and the one where investment in supplementation has the greatest return. Foetal growth accelerates dramatically in the final six weeks — 70% of the lamb's birthweight is added during this period. The ewe's rumen capacity is simultaneously compressed by the expanding uterus, physically limiting the volume of feed she can consume. The combination creates the conditions for pregnancy toxaemia (twin lamb disease, ketosis) in ewes carrying multiples that are not receiving adequate energy supplementation.

Target intake in the final six weeks: supplement ewes on pasture (or replace pasture) with 300 to 500 grams of grain per head per day for single-bearing ewes, 400 to 600 grams for twin-bearing ewes, and 500 to 700 grams for triplet-bearing ewes. Pregnancy scanning at 60 to 70 days of gestation identifies which ewes are carrying multiples — draft them into separate mobs for targeted feeding. The scanning cost (typically $1 to $2 per ewe) is repaid many times over in reduced mortality from pregnancy toxaemia and improved lamb survival rates from adequately-nourished ewes.

Lactation represents the peak nutritional demand across the entire production cycle. A ewe nursing twins is drawing on her body reserves to supplement whatever her intake provides — an unsupplemented ewe on dry summer pasture nursing twins will lose 10 to 15% of her bodyweight during the first six weeks of lactation. If BCS falls below 2 in a lactating ewe, milk production and lamb growth both suffer, and the ewe's ability to conceive at the next joining is compromised. Ensure maximum quality roughage is available to lactating ewes at all times, supplement with grain where pasture quality or quantity is limiting, and monitor BCS monthly from lambing through weaning.

Weaner management is the most technically demanding phase of sheep nutrition for most producers. Weaners — lambs removed from their mothers — undergo a stressful transition from milk-based to pasture-based nutrition and are simultaneously facing their first worm challenge on pasture without maternal immune protection. They have high requirements for both energy and protein (14 to 16% CP from a high-ME ration) and are the most likely class of sheep to exhibit rapid condition loss and high mortality when nutritional management fails. Priority access to the highest quality pasture on the property is the minimum requirement. Supplementation with lupins and oaten hay or a commercial weaner pellet is appropriate where pasture quality is below target. Weaner management is worth its own systematic attention — it determines the condition of the ewe replacements entering their first joining.

Drought is a recurring feature of Australian sheep production, and how a producer responds to drought conditions is one of the most consequential management decisions they will make. The financial and welfare outcomes of a drought are determined not by the drought itself — which is beyond any producer's control — but by the decisions made in the weeks and months before conditions become extreme.

The key decision in developing drought conditions is how quickly to reduce stocking rate relative to the decline in feed availability. The universal error is waiting too long. Producers consistently hold onto stock through the early stages of drought, hoping for rain, burning through their pasture reserve, then facing a choice between destocking at the worst possible market conditions (when all their neighbours are doing the same, driving prices down) and feeding large numbers of animals on expensive purchased feed. Earlier, more aggressive destocking preserves more pasture for retained animals, reduces feed costs, and in most cases results in better financial outcomes even though it feels counterintuitive at the time.

When feeding dry sheep through drought, the cheapest adequate maintenance ration should be the starting point. Oaten hay or low-quality roughage supplemented with a protein source (200 grams of lupins or 100 grams of urea-based supplement per head per day — with proper urea introduction protocol) maintains dry sheep at minimal cost. As the feeding period extends, move to grain-based rations for more cost-effective energy delivery. The key is accurate calculation of what the mob needs and what you are providing — feeding by eye without calculation means you are either overfeeding (expensive) or underfeeding (welfare problem).

Lot feeding (confining animals to a small area and delivering all feed) becomes appropriate when the paddock feed base is essentially exhausted. It concentrates stock and allows accurate feed delivery and monitoring, reduces walking time and energy expenditure, and allows better management of weak or poor-condition animals. The welfare risks of lot feeding — respiratory disease from dust and confinement, foot problems from contaminated lot surfaces, polioencephalomalacia from high grain rations — require active monitoring and management. Lot-fed sheep must have continuous access to roughage alongside grain rations, clean water at all times, and daily welfare checks.