How Does Flushing Increase Lamb Numbers?

In sheep farming, few management practices deliver returns as quickly and predictably as flushing. Yet many producers still ask: Does flushing really increase lamb numbers on Eastern Cape veld? And if so, how much difference does it actually make?

In this article, we unpack what flushing does inside the ewe, why body condition score (BCS) is critical, and what results you can realistically expect under Eastern Cape grazing conditions.

What Is Flushing in Sheep Farming?

Flushing is the practice of improving a ewe’s nutrition for 2–4 weeks before mating and continuing for about 2–3 weeks into the breeding season.

The goal is simple:
Increase ovulation rate and improve embryo survival to produce more lambs per ewe joined.

Flushing can be achieved through:

• High-quality pasture

• Energy-rich supplementary feeding

• Strategic lick or concentrate programs

• Moving ewes to better veld before mating

On Eastern Cape veld, where grazing quality fluctuates seasonally, strategic supplementation is often essential to achieve effective flushing.

What Happens Inside the Ewe During Flushing?

Flushing is not just about weight gain — it is about hormonal response.

When a ewe’s energy intake increases:

1. Blood glucose levels rise

2. Insulin and metabolic hormones increase

3. The reproductive system responds

4. Ovulation rate improves

More ova released = higher chance of twins.

However, this response only works if the ewe is in the correct physiological state — which is where Body Condition Score becomes critical.

Why Body Condition Score (BCS) Matters More Than Feed Alone

Body Condition Score measures fat reserves on a scale of 1 (very thin) to 5 (obese).

For optimal flushing response:

• Thin ewes (BCS below 2) respond well — but need time.

• Moderate ewes (BCS 2.5–3) show the strongest ovulation response.

• Overfat ewes (BCS above 4) often show reduced fertility.

On Eastern Cape veld, many ewes drop condition during dry months. Attempting to flush ewes that are too thin without enough time before mating may result in disappointing conception rates.

Key principle:
Flushing works best when ewes are rising in condition, not losing weight.

How Many Extra Lambs Can Flushing Realistically Add?

Research and practical experience suggest:

• Ovulation rate can increase by 10–25%

• Lambing percentage can improve by 5–20%

• Twin rates often increase noticeably

Under Eastern Cape veld conditions, realistic improvements are:

Management LevelExpected ImprovementBasic veld onlyMinimal responseVeld + strategic energy supplement5–10% increaseWell-managed flushing program10–20% increase

Example:
If your baseline lambing rate is 85%, flushing may increase it to 95–105%, depending on breed and condition.

That means:

• An extra 10–20 lambs per 100 ewes

• Significant income increase with relatively low input cost

Eastern Cape Veld Considerations

The Eastern Cape presents unique challenges:

• Seasonal feed gaps

• Variable rainfall

• High parasite pressure

• Declining pasture quality before breeding season

Because veld quality often declines before mating, relying on grazing alone rarely produces maximum ovulation response.

Strategic supplementation during the flushing window can:

• Stabilise rumen function

• Improve energy intake

• Reduce weight loss during early pregnancy

• Improve embryo survival

Consistency is key. Sudden feed changes or nutritional stress during early pregnancy can reduce conception gains achieved during flushing.

When Should You Start Flushing?

Flushing should begin:

• 2–4 weeks before rams are introduced

• Continue for at least 2 weeks after mating starts

This ensures:

• Maximum ovulation response

• Improved embryo implantation

• Better early pregnancy survival

Stopping supplementation too early can reduce the benefits.

Does Breed Influence Flushing Response?

Yes.

• Merino-type breeds show strong ovulation response.

• Dual-purpose breeds respond well when condition improves.

• Indigenous breeds may show smaller but still valuable increases.

Genetics set the ceiling. Nutrition determines whether you reach it.

Common Flushing Mistakes

1. Starting too late

2. Flushing ewes that are too thin without enough recovery time

3. Stopping feed immediately after mating begins

4. Ignoring parasite burdens

5. Not grouping ewes by condition

Effective flushing is planned, not reactive.

Is Flushing Worth It on Eastern Cape Veld?

For most commercial producers, yes.

If properly managed, flushing can:

• Increase lamb numbers

• Improve flock profitability

• Reduce barren ewes

• Improve overall flock performance

However, it only works when:

• Body condition is monitored

• Supplementation is consistent

• Parasites are controlled

• Ewes are managed as breeding animals, not just grazers

Frequently Asked Questions (FAQ)

1. How long should I flush ewes before mating?

Ideally 2–4 weeks before introducing rams and continue for 2–3 weeks after mating starts.

2. Can flushing work on poor Eastern Cape veld without supplements?

Response is usually limited. Strategic energy supplementation significantly improves results.

3. What is the ideal Body Condition Score for mating?

Between 2.5 and 3.5 at mating for optimal fertility response.

4. How many extra lambs can flushing produce?

Realistically 5–20 extra lambs per 100 ewes, depending on breed, management and starting condition.

5. Should thin ewes be flushed?

Yes, but they need sufficient time to recover condition before mating. Very thin ewes will not respond effectively without proper preparation.

6. Does flushing increase twin lambs?

Yes. Flushing primarily increases ovulation rate, which increases the chance of twins.

Final Thoughts

Flushing is not a miracle shortcut. It is a strategic nutritional tool that, when applied correctly, improves ovulation rate, embryo survival and lamb numbers.

On Eastern Cape veld, where grazing quality fluctuates, planned supplementation before and during mating can significantly improve reproductive performance.

The difference between average and excellent lambing percentages often comes down to preparation.

If you want more lambs on the ground next season, the work starts weeks before the ram goes in.

For tailored feeding solutions suited to Eastern Cape conditions, visit www.stormcreteanimalfeeds.com.