Ewe body condition
Ewes that are too thin or too fat at joining conceive less reliably. Sorting by condition score six to eight weeks before the ram goes in leaves time to fix it.
Breeding & Reproduction
Ewe Conception Rate Calculator
Enter how many ewes went to the ram and how many scanned in lamb. The calculator gives the conception rate, the number and share of empty ewes, and how the result compares with the usual flock target. Add the ewes that were marked a second time and the calculator shows how many ewes held to the first service.
- ✓ Runs entirely in your browser
- ✓ No account needed
- ✓ Free to use
Your result
Ewe Conception Rate Calculator result
Conception rate95%
On target for a mature ewe flock in good condition.
Copied ✓
Estimates for planning only. Results depend on the figures you enter and on typical published values, and real animals and farms vary. Consult a qualified veterinarian, nutritionist or adviser before making animal health, feeding or financial decisions.
The breakdown
Updates as you type- Ewes in lamb
- 95
- Empty ewes
- 5
- Empty rate
- 5%
The basics
What Is Ewe Conception Rate?
Ewe conception rate is the percentage of ewes put to the ram that are confirmed pregnant, measured at ultrasound scanning 45 to 90 days after mating. A flock with 95 pregnant ewes from 100 joined ewes has a 95% conception rate and a 5% empty (barren) rate.
The Ewe Conception Rate Calculator divides ewes scanned in lamb by ewes joined and multiplies by 100. The calculator returns first-cycle conception as well, when the ram wore a marking harness (raddle) and the returns to heat were counted after the 17-day oestrous cycle.
What the Ewe Conception Rate Calculator Calculates
The Ewe Conception Rate Calculator returns 4 results:
- Conception rate: pregnant ewes as a percentage of ewes joined
- Empty ewes: the number and percentage of barren ewes
- First-cycle conception: ewes that held to the first service
- Target check: the result against the 95% benchmark for mature ewes
When to Use the Ewe Conception Rate Calculator
There are 3 main uses for the Ewe Conception Rate Calculator:
- Review ram and ewe performance on scanning day
- Compare joining groups, ram teams or ewe age classes
- Decide which empty ewes to cull or join again
Getting started
How to Use the Ewe Conception Rate Calculator
To use the Ewe Conception Rate Calculator, follow 3 steps: count the ewes put to the ram, then enter the ewes confirmed in lamb, then add returns if you recorded them. The result updates as you type.
-
Step 1: Count the ewes put to the ram
Use every ewe that was joined, not just the ones present at scanning. That keeps the figure honest from year to year.
-
Step 2: Enter the ewes confirmed in lamb
Use your scanning result. Ultrasound scanning is most reliable between about 45 and 90 days after mating.
-
Step 3: Add returns if you recorded them
If the ram wore a marking harness and you changed crayon colour, enter the ewes that were marked a second time.
The maths
Ewe Conception Rate Formula
Conception rate is simply the share of joined ewes that are pregnant.
Conception rate (%) = Ewes in lamb ÷ Ewes put to the ram × 100
First-cycle conception uses the same sum with the ewes that did not return to heat: joined ewes minus returns, divided by joined ewes.
Worked example
- Ewes put to the ram 100
- Ewes scanned in lamb 95
- Conception rate 95 ÷ 100 × 100 = 95%
- Empty ewes 5 ewes, 5%
Reference
What Is a Good Conception Rate for Sheep?
How to read your result for a mature ewe flock joined in the normal breeding season.
| Conception rate | Empty ewes | What it suggests |
|---|---|---|
| 98% or more | 2% or fewer | Excellent. Rams and ewes were both in good order. |
| 95 to 97% | 3 to 5% | On target for mature ewes. |
| 90 to 94% | 6 to 10% | Below target. Review ewe condition and ram numbers. |
| Under 90% | More than 10% | Investigate the cause with your vet. |
Ewe lambs and out-of-season matings usually run lower than mature ewes joined in autumn, so judge those groups separately.
Glossary
Ewe Conception Rate Terms Explained
6 terms appear in the Ewe Conception Rate Calculator and in the guidance around it.
Empty ewe rate (barren rate)
- The empty ewe rate, or barren rate, is the percentage of joined ewes that are not pregnant at scanning. Conception rate plus empty ewe rate equals 100%.
Scanning percentage
- Scanning percentage is the number of foetuses counted at ultrasound per 100 ewes joined. A flock with a 95% conception rate and 1.8 foetuses per pregnant ewe scans at 171%.
Body condition score (BCS)
- Body condition score (BCS) grades the fat and muscle cover over the loin on a 1 to 5 scale. Lowland ewes conceive best at BCS 3 to 3.5 at joining.
First-cycle conception
- First-cycle conception is the share of ewes that hold to a service in the first 17 days of joining. A high first-cycle figure gives a compact lambing.
Breeding soundness exam
- A breeding soundness exam checks the testicles, feet, teeth and body condition of a ram about 8 weeks before joining.
Infectious abortion
- Toxoplasmosis and enzootic abortion of ewes (EAE) are 2 common infectious causes of lost pregnancies. Toxoplasmosis in early pregnancy kills the embryo, and the ewe scans empty.
Good to know
What Affects Ewe Conception Rate
3 factors decide ewe conception rate: ewe body condition, ram fertility and stress or disease after mating.
Ram fertility and numbers
One sub-fertile ram can leave a whole group empty. Check rams well before joining and run enough of them for the size of the group.
Stress and disease
Rough handling, shearing, heat, a sudden feed change or an infectious cause of abortion in the weeks after mating can all show up as empty ewes.
Answers
Frequently Asked Questions
Common questions about the ewe conception rate calculator and the numbers behind it.
What is a good conception rate for ewes?
Most well-managed flocks aim for 95% or more of mature ewes in lamb, which means 5% or fewer empty. Ewe lambs and out-of-season matings commonly come in lower.
How is conception rate different from lambing percentage?
Conception rate counts ewes: how many of the ewes joined are pregnant. Lambing percentage counts lambs born per 100 ewes joined. A flock can have a high conception rate and a modest lambing percentage if most ewes carry singles.
When can I measure conception rate?
At pregnancy scanning, usually 45 to 90 days after mating. Before that, the share of ewes that are not marked again by the ram gives an early indication.
What should I do with empty ewes?
Many flocks cull ewes that are empty after a full joining with fertile rams, especially if it is the second time. Check condition, teeth and udder first: one empty year in a good young ewe is often bad luck.
🐑 Free · no sign-up · works offline
Get your ewe's exact lambing date in seconds
Enter one breeding date and get the due date, the 142-152 day window and a dated milestone plan, scanning, feeding, vaccination, shearing and lambing.