Sponge Oestrus Synchronisation in Sheep: Steps and Key Rules

Sponge synchronisation means bringing a group of ewes into heat at the same time by placing a vaginal sponge impregnated with a progesterone-like hormone for about 12 to 14 days, then removing it, often together with a hormone injection chosen by the vet. Most ewes then come into heat within about 1 to 2 days, and rams go in or artificial insemination is done in that window. The result: lambing grouped about 147 days later.

Many breeders in Saudi Arabia turn to sponges because they solve an old problem: lambing spread over three months, which makes feeding, vaccination and selling hard to organise. But a sponge is a veterinary tool, not a magic fix. Success depends more on the condition of the ewes before the sponge than on the sponge itself, and the programme should be run with your vet. This article explains why it is used, the general steps, what makes it fail, and how to record each date.

Why breeders use sponges

• Grouped lambing within a few days instead of weeks, so you prepare lambing pens, workers and night checks once.
• Planning for a sale season, such as a batch of lambs for Ramadan or Hajj, by counting back from the target sale date.
• Uniform batches of lambs in age and weight, easier to wean, finish and price.
• Making artificial insemination practical, since AI needs an accurate heat date.
• Supporting an accelerated system; see 3 lambings in 2 years.

Remember: the sponge synchronises the timing of heat. It does not fix a thin or sick ewe or a ram with poor fertility.

Before the sponge: body condition comes first

Most sponge failures start before the sponge goes in:

1. Body condition. The usual target is about 2.5 to 3.5 on a 1-to-5 scale. Thin ewes respond poorly and over-fat ewes can be less fertile. Start flushing ewes before mating a few weeks ahead if they need it.
2. Confirm they are not pregnant. A sponge is not for a pregnant ewe; check if in doubt.
3. Enough time after lambing. A ewe that has lambed recently needs time before being synchronised; your vet sets the right interval for your flock.
4. General health. Leave sick or lame ewes, or ewes with mastitis, out of the programme. Agree with your vet on timing vaccination and parasite control so they do not coincide with mating and early pregnancy.
5. The rams. Check rams well before the date: testicles, legs and body condition. More in choosing a breeding ram.
6. Heat. Summer heat lowers fertility in both rams and ewes. Provide shade and water, and avoid the hottest weeks if you can.

The general steps of sponge synchronisation

These general steps are for understanding and planning. The actual protocol, which hormones are used and their timing are decided by the vet for your flock:

Hygiene: a small detail with a big effect

The sponge goes inside the vagina, and any contamination can pass infection from ewe to ewe. Clean and disinfect the applicator between every ewe as your vet advises, wear gloves, work in a clean area with little dust, and never insert a sponge that has dropped on the ground. At removal, if you see heavy foul-smelling discharge or bleeding, tell your vet.

How many rams do you need?

This is where many breeders go wrong. In ordinary natural mating, one ram can cover a large group because heats are spread over weeks. After sponges, dozens of ewes come into heat within a day or two, so you need far more rams; many breeders work with about one mature ram for every 8 to 10 synchronised ewes. Confirm the number with your vet based on the rams' age and condition, and rest them between programmes.

When sponges are not a good idea

• When ewes are thin or sick; fix feeding and health first.
• When you do not have enough good rams and no access to artificial insemination.
• When you cannot handle many births in a few days: pens, workers, colostrum, night checks.
• When the goal is just "to try it", with no plan for selling or weaning the lambs afterwards.

Anything to do with hormones, their type and any withdrawal period before ewes are slaughtered or their milk is sold is decided by your vet alone. Do not buy sponges or hormones from unreliable sources.

Record every date as a stage in Throf

The value of sponges lies in precise dates, and dates are lost without records. For each ewe, note: sponge insertion date, removal date, any sponge lost, mating date and ram (or AI), pregnancy scan result, and expected lambing about 147 days later. You can work out the dates with the gestation calculator.

In Throf you record sponge insertion as a treatment for the whole group of ewes, with a reminder for removal day and a task for the worker in charge. On mating day you change the group's stage to insemination in one step, natural or artificial, then to pregnancy and close to birth, so you know which ewes to watch this week. The natural and artificial insemination reports and the pregnancy report show the success rate for each ram and each group, so you can decide whether to repeat the programme in your next breeding season.