by Terry Barker
Jacob sheep are a breed close to my heart, and like many traditional breeds, they march to the beat of a seasonal drum. Ewes naturally cycle as the days shorten, which means most of us see lambs in the spring. It’s a rhythm that works, but sometimes, you need a different tune. Maybe you want lambs on the ground earlier for a specific market or show, or perhaps you want to split your lambing period to ease the workload. This is where out-of-season breeding comes in, using tools like CIDRs and sponges to gently nudge your ewes’ reproductive cycles.
What are CIDRs and Sponges?
Think of these devices as temporary hormonal assistants. Both are small, prescription-only devices that you insert into the ewe’s vagina. They work by slowly releasing progesterone, a hormone that essentially convinces the ewe’s body that it’s pregnant, preventing ovulation.
- CIDRs (Controlled Internal Drug Release devices) are typically Y-shaped plastic devices. They’re easy to insert and tend to be less messy.
- Sponges are soft, tampon-like foam blocks soaked in progestogen, a synthetic version of progesterone.
After being in place for about 12 to 14 days, the device is removed. The sudden drop in progesterone tells the ewe’s body to prepare for ovulation. Within a tight window of 24 to 48 hours, she should come into season. If you have a ram on standby, mating usually follows. For a more predictable and powerful response, especially out of season, many keepers use a teaser ram or a hormone injection like PMSG at the time of removal.
Why Go Off-Season?
There are several reasons why I—and other keepers—might consider this approach:
- Catching the Early Market: Lambs born earlier may be ready for spring shows or early markets when prices are at their highest.
- Balancing the Books (and Your Back): Splitting your lambing period can help you manage your workload, spreading the sleepless nights and intensive care over a longer period, in controlled batches.
- Managing Your Flock: It’s a great way to synchronise large groups for more efficient AI or to advance the breeding of a young shearling without waiting a whole year.
- Making the Most of Your Space: If you’ve got limited indoor shelter, lambing earlier can help you avoid the muddy chaos of a wet spring.
A Step-by-Step Guide to Synchronising Ewes
This isn’t a strategy you can rush into. It requires careful planning and attention to detail.
1. Choose Your Ewes Wisely: Start with healthy ewes in good condition (a body score of 3.0 to 3.5 is ideal). They should be proven breeders, disease-free, and already cycling naturally.
2. Insert the Device: Always wear gloves and use a lubricated applicator to keep things clean. Hygiene is non-negotiable here.
3. Set a Timer for 12–14 Days: This is the sweet spot. Leaving the device in for too long increases the risk of infection.
4. Remove the Device: I like to mark the date and time on a calendar or in my phone’s notes. Consistency is key.
5. Consider PMSG/eCG: Administering this hormone injection at the time of removal gives you a much stronger and more predictable ovulation response, especially out of season.
6. Introduce the Rams: Some people bring in a teaser ram at the time of removal, and then the fertile ram 24 to 48 hours later. I choose to put my ram in straight away.
7. Watch and Wait: The ewes should cycle within a very tight window, and lambing will follow a similarly synchronised pattern about five months later.
Other Ways to Lamb Out of Season
While CIDRs and sponges are a highly effective method, they’re not the only option. Some shepherds prefer more natural approaches or a combination of strategies to encourage out-of-season breeding.
- The “Ram Effect”: This is a powerful, natural form of synchronisation. Ewes that have been kept entirely separate from rams for at least a month will often come into season shortly after a ram is introduced. The sight, sound, and smell of the ram triggers a hormonal response in the ewe. Using a teaser ram first can be a great way to “jump-start” the process and save your fertile ram’s energy for when the ewes are ready.
- Flushing: Improving the ewes’ nutrition just before breeding can dramatically boost reproductive performance. By increasing their energy intake, you put them into a positive energy balance, which can lead to higher ovulation rates, even during off-season periods.
- Breed Selection: While Jacob sheep are seasonal, some breeds, or specific lines within a breed, are naturally less seasonal than others. Focusing on genetics for reduced seasonality can, over time, help you build a flock that is more willing to lamb out of the normal spring window.
The Fine Print: Pros and Cons
Like any intervention, there are trade-offs to consider.
Pros:
- A very tight lambing period, often just 5–7 days.
- Perfect for AI and embryo transfer programs.
- Gives you ultimate control over your breeding dates.
- It’s a reliable way to bring ewes into season in the spring or summer.
Cons:
- The cost: CIDRs, PMSG, applicators, and vet bills all add up.
- A risk of infection if hygiene isn’t perfect.
- Not a fool proof solution—some ewes, especially if they’re too far out of their natural cycle, just won’t respond.
- It requires precision and planning.
- The use of hormones may affect organic certification.
A Final Thought on Responsibility
It’s crucial to remember that in the UK, CIDRs and sponges are prescription-only medicines. You need to get them from a vet and follow their instructions to the letter. This isn’t a quick fix; it’s a responsible, carefully considered tool.
For me, the goal isn’t to force my flock to do something unnatural. It’s about having the flexibility to manage my farm in a way that works for me and my schedule. Synchronising ewes for out-of-season lambing isn’t for everyone, but done with care and forethought, it can be a game-changer for your flock management.
What are your thoughts on out-of-season lambing? Have you tried it, or are you a firm believer in letting nature take its course?