Flushing means putting ewes on a rising plane of nutrition for a short period around ram introduction. The aim is to lift ovulation rate, so more ewes release two or more eggs and more twins are conceived.
In practice it usually means better pasture or a modest grain supplement:
- US extension: starting about two to three weeks before the rams go in and continuing into the first cycle.
- Australian research: a shorter feed boost of about a week either side of joining.
It works best in ewes that are slightly below target body condition. It does little for ewes already in good condition, and nothing useful for fat ewes. It cannot fix months of underfeeding.
This guide covers short-term nutrition before and during joining only. Feeding pregnant ewes is covered separately in late-gestation ewe nutrition.
How nutrition affects ovulation
Nutrition influences how many eggs a ewe releases in three ways. EverGraze research material, produced with Meat & Livestock Australia and Australian Wool Innovation, describes them as follows:
| Effect | What it means | Practical takeaway |
|---|---|---|
| Static effect | Heavier, better-conditioned ewes ovulate more eggs than lighter ewes of the same breed. EverGraze cites about 1 to 3% more ovulations per extra kilogram of live weight at joining. | Body condition built over months is the biggest lever |
| Dynamic effect | Ewes gaining weight and condition before joining ovulate more than ewes holding steady or losing | A rising plane of nutrition helps |
| Acute effect | A short burst of high-energy or high-protein feed, for about 4 to 6 days, can raise ovulation rate without visible weight gain | A brief, well-timed supplement can still help |
The critical window is the few days before ovulation. In a 17-day cycle, EverGraze identifies roughly days 10 to 14 as the period when nutrition has most influence on the next ovulation.
That explains two things. First, flushing does not need to last months. Second, body condition at joining matters more than flushing itself. Beef + Lamb New Zealand estimates lambing percentage rises by about 6 to 10% for each extra condition score unit at mating, with flushing adding perhaps another 5 to 10%.
How much difference does flushing make?
Published responses vary widely, and the headline figures are often quoted without context.
| Source | Reported response | Context |
|---|---|---|
| Kentucky Sheep & Goat; Washington State University Extension | About 10 to 20% more lambs, mainly as extra twins | US farm flocks, grain or improved pasture |
| Beef + Lamb New Zealand | Flushing may add about 5 to 10% | New Zealand pasture systems |
| EverGraze (lucerne flushing) | About 10% higher ovulation rate on average | Merino ewes in dry years with little green feed |
| EverGraze (lupins) | Up to about 54% higher ovulation rate, but highly variable | Synchronised ewes fed about 500 g of lupins daily |
| Birchip Cropping Group | About 20 to 30% higher ovulation rate | Lupins at 0.5 kg per head per day, 7 days before and 7 days after joining |
Two cautions:
- Ovulation rate is not lambs weaned. Extra eggs have to survive to become lambs, and extra lambs have to survive birth and rearing.
- The biggest responses come in specific situations, such as thin ewes, dry seasons or synchronised flocks. A flock already in good condition on good grass may see very little.
AHDB advice quoted in Farmers Weekly describes flushing as a back-up plan. It says flushing has little effect if the ewe is already in good condition, and that the priority should be getting condition right well ahead of mating.
Which ewes benefit, and which do not
| Ewe group | Likely response | Notes |
|---|---|---|
| Thin ewes, about BCS 2.0 to 2.5 | Best response | Kentucky extension finds ewes at BCS 2 to 2.5 most responsive; but very thin ewes also need longer condition building |
| Moderate ewes, about BCS 2.5 to 3.0 | Useful response | The classic flushing group |
| Ewes at target condition, BCS 3.0 to 3.5 | Small or little response | Better to hold steady than push harder |
| Fat ewes, BCS 3.5 to 4.0 or more | No benefit | Kentucky extension reports no response at BCS 3.5 and above; over-fat ewes are not a flushing target |
| Mature ewes | Better response than young ewes | Ontario guidance via Ohio State notes mature ewes respond better than yearlings |
| Highly prolific breeds | Smallest relative response | Already ovulating at a high rate |
| Ewes joined early or late in the season | Larger response | Ontario guidance notes responses tend to be greater away from the peak of the breeding season |
| Ewe lambs | Uncertain | Sources disagree, see below |
Ewe lambs. Washington State University extension says no flushing effect is noted in ewe lambs, and Kentucky extension says flushing is usually not necessary for them. Penn State extension recommends feeding bred ewe lambs to keep them growing, including grain. For ewe lambs, steady growth to a target weight matters far more than a short flush. See breeding ewe lambs.
Score before you spend
The single most useful step is to body condition score every ewe well before joining, and group them by score. Feed the thin group better, leave well-conditioned ewes on maintenance, and keep fat ewes on poorer grazing. How to score by hand is covered in the body condition scoring guide.
Body condition targets at joining
Targets vary by system and country. Published examples:
| Source | Target condition score at mating | Context |
|---|---|---|
| AHDB (UK) | About 3.5 lowland, 3 upland, 2.5 hill | Target for each ewe, not a flock average |
| Teagasc (Ireland) | At least 3.5, “fit not fat” | Irish lowland flocks |
| Beef + Lamb New Zealand | About 3 to 4 | New Zealand pasture systems |
| Lifetime Wool (Australia) | At least 3 | Merino flocks; ewes below 3 more likely to respond to extra feed |
Condition takes weeks to change. CAFRE in Northern Ireland suggests at least 6 to 8 weeks of improved feeding per condition score unit, and Teagasc estimates about 10 weeks on good grass to move a ewe from 2.5 to 3.5. Flushing alone cannot close a large gap in two weeks.
When to start and stop flushing
There is no single schedule. The two main published approaches are:
US and Canadian approach: a few weeks before and into joining
- Ontario guidance (via Ohio State) suggests starting about 2 weeks before breeding and continuing 2 to 4 weeks into the breeding season.
- South Dakota State University suggests flushing about 2 to 3 weeks before and after breeding.
Ontario guidance also links the length of flushing to starting condition:
| Starting condition score | Suggested flushing length (Ontario guidance) |
|---|---|
| 1.5 | About 9 weeks |
| 2.0 | About 6 weeks |
| 2.5 | About 3 weeks |
| 3.0 | About 2 weeks |
Note that the longer periods for thin ewes are really condition building, not a short flush.
Australian approach: a short burst around joining
- EverGraze suggests grazing quality pasture for about one week before and one week into joining, then moving ewes off large amounts of high-quality pasture.
- Birchip Cropping Group trials used lupins at 0.5 kg per head per day for 7 days before and 7 days after the start of joining.
After the rams go in: steady, not a feast or famine
What happens after mating matters too, and the evidence points two ways:
- Avoid sharp drops in nutrition in the first weeks after mating. Washington State and South Dakota State extension both advise against a sudden fall in feed at this time.
- Avoid pushing very high feeding in the days after mating. EverGraze notes that embryos are sensitive around days 11 to 12 after mating. A study by Parr and colleagues (1987) found lower pregnancy rates in ewes on a high feeding level after mating than in ewes on moderate or low levels.
The safe message is to hold nutrition steady at a moderate level through the first month after joining. Avoid unnecessary handling, transport and stress in that period too.
How to flush: pasture options
Good pasture is the cheapest flushing feed where it is available.
- Save a paddock of fresh, leafy pasture for the flushing period.
- Pasture targets (Beef + Lamb New Zealand): about 5 to 6 cm of pasture height. Ewes lose condition when pasture drops below about 3 cm or around 1,500 kg of dry matter per hectare. About 1.0 to 1.3 kg of dry matter per ewe per day is needed just to maintain condition.
- Dry-season green feed (EverGraze): in dry years, about 350 kg of green dry matter per hectare delivered most of the ovulation benefit of lucerne flushing for Merino ewes.
- Introduce new forages gradually, especially brassicas and lush legumes, to avoid digestive upsets.
How to flush: grain and supplements
Where pasture is short, a grain supplement can provide the rising plane:
- US extension: about 0.5 to 1 lb (about 225 to 450 g) of grain per ewe per day (Kentucky, Washington State). South Dakota State suggests corn at about 1 lb per head per day.
- Australia: lupins at about 0.5 kg per head per day (Birchip Cropping Group).
Introduce grain slowly
Sudden grain feeding can cause acidosis. Washington State University extension describes stepping up gradually. It starts at about 0.25 lb per ewe per day split over two feeds, then increases in steps to the target amount over several days.
Practical points:
- Provide enough trough space so all ewes can eat at once, or timid ewes miss out.
- Feed at the same time each day.
- Make sure ewes have constant access to clean water.
- Do not suddenly stop grain at joining. Reduce gradually once the flushing period is over.
These amounts are general extension figures, not a ration for your flock. Feed availability, grain type, ewe size and pasture all change the right amount. A nutritionist or adviser can help balance a ration.
Risks and when flushing is a waste
Red clover and oestrogenic pastures
Some legumes contain plant oestrogens that can interfere with fertility:
- Red clover: FAS Scotland advises avoiding red clover for six weeks before and six weeks after tupping. It warns that long-term grazing on red clover can cause permanent infertility. A more recent farmer-led trial reported no fall in scanning percentage, but the official guidance has not changed.
- Fresh legumes: Washington State University extension notes that fresh alfalfa, clovers and some other legumes can interfere with cycles and ovulation, while hays do not have the same effect.
- Stressed lucerne (alfalfa): EverGraze warns that lucerne affected by fungal disease or aphid stress can produce coumestans, which can reduce ewe fertility.
Other ways flushing goes wrong
- Flushing fat ewes. No benefit, and extra cost.
- Blanket-feeding the whole flock instead of the ewes that will respond.
- Starting too late or stopping abruptly at joining.
- Grain introduced too fast, risking acidosis.
- Relying on flushing to rescue ewes that are far too thin.
- Ignoring the rams. Well-flushed ewes need fertile, sound rams. See the ram breeding soundness exam guide.
- Creating lambs you cannot manage. More twins and triplets mean more feed, labour and fostering later. See twins, triplets and litter size.
Minerals: test before you supplement
Trace element deficiencies can reduce fertility whatever the energy supply. Guidance from AHDB and veterinary laboratories suggests blood testing a small group of representative ewes, around six, before tupping. That way you know whether copper, cobalt, selenium or iodine supplementation is actually needed before buying boluses or drenches.
Take particular care with copper. Sheep are sensitive to copper toxicity, so only supplement it on veterinary or nutritionist advice.
A flushing plan: example timeline
This example is for a flock planning to put rams in on a set date.
| When | Task |
|---|---|
| 10 to 12 weeks before rams in | Body condition score every ewe; check teeth and feet; decide culls |
| 8 to 10 weeks before | Draft thin ewes onto better grazing to build condition; blood-test for trace elements if needed |
| 6 to 8 weeks before | Rescore; check rams; plan flushing paddocks or grain |
| 2 to 3 weeks before (or about 1 week, for a short pasture or lupin flush) | Move target ewes onto a rising plane of nutrition |
| Rams in | Continue flushing into the first cycle; fit marking harnesses |
| First month after joining | Hold nutrition steady; avoid sudden feed changes, stress and transport |
Worked example
A 200-ewe flock is scored eight weeks before joining:
- 30 ewes at BCS 2.0: move straight onto the best grazing to build condition. They need longer than a short flush.
- 110 ewes at BCS 2.5 to 3.0: the main flushing group. Move onto saved pasture about two to three weeks before rams in, or introduce grain gradually.
- 60 ewes at BCS 3.5 or above: hold on maintenance grazing. Flushing them is unlikely to pay.
Scoring and grouping focuses feed on the 140 ewes most likely to respond, instead of feeding all 200.
Planning ahead after joining
Flushing raises litter size, and larger litters change the whole pregnancy plan. Record service dates from marking harnesses. Then use the Sheep Gestation Calculator to estimate when each group will lamb, and plan scanning, late-pregnancy feeding and lambing supervision from those dates.
Frequently asked questions
How many weeks before breeding should I flush ewes?
Commonly about two to three weeks before rams go in, continuing into the first cycle, according to US and Canadian extension guidance. Australian research has used shorter programmes of about one week before and one week after the start of joining. Thin ewes need a longer period of condition building first.
Is flushing worth it if my ewes are already in good condition?
Usually not much. AHDB advice describes flushing as having little effect on ewes already in good condition, and Kentucky extension reports no response in ewes at condition score 3.5 or above. Hold them steady instead.
How much grain should I feed to flush ewes?
US extension guidance commonly suggests about 0.5 to 1 lb (about 225 to 450 g) of grain per ewe per day. Australian trials have used lupins at about 500 g per head per day. Introduce grain gradually over several days to avoid acidosis, and adjust for pasture quality and ewe size.
Should I flush ewe lambs?
Sources disagree. Some extension services report little or no flushing effect in ewe lambs. For ewe lambs, reaching a target breeding weight through steady growth is more important than a short flush.
Can ewes graze red clover at mating?
FAS Scotland advises keeping ewes off red clover for about six weeks before and six weeks after tupping, because plant oestrogens can reduce fertility. Some fresh legumes and stressed lucerne can have similar effects.
Sources and further reading
- EverGraze (with MLA and AWI): Exchange note on nutrition and ovulation
- Birchip Cropping Group: Ewe management in the lead-up to joining
- AWI Extension WA: Strategies to increase conception and reproductive rates (Lifetime Wool)
- Beef + Lamb New Zealand: Ewe body condition drives conception rates
- Kentucky Sheep and Goat: Flushing, yes or no?
- Washington State University Extension: Nutritional flushing of small ruminants
- Ohio State University Sheep Team: Flushing the ewe flock
- South Dakota State University Extension: Nutritional considerations for flocks during breeding season
- Penn State Extension: Feeding and managing your bred ewe lambs
- Teagasc: Optimising ewe and ram condition ahead of breeding
- CAFRE: Pre-breeding ewe management
- AHDB (via Farmers Weekly): Ewe nutrition requirements through the production year
- FAS Scotland: Beware red clover
- Merck Veterinary Manual: Reproductive physiology of sheep
- Parr and colleagues (1987): study of feeding level after mating and pregnancy rate, Journal of Reproduction and Fertility
This article is general husbandry guidance, not veterinary advice. For ration formulation, trace element supplementation or flock fertility problems, consult your veterinarian or a qualified nutritionist.
Plan your lambing dates: use the free Sheep Gestation Calculator to turn a breeding date into an expected lambing date, a 142–152 day window and a full milestone timeline. Estimates only, always consult a veterinarian for animal-health decisions.
