Frequently Asked Questions
Research Matters!
Questions and Answers
The following questions were asked by audience members at the Research Matters! seminar at Charles Sturt University on 16 October 2024. Some were answered during the seminar and the full list is shown here.
1. Using Regulin in different breeds
How does Regulin work in various different breeds, and do you get different results, lambing rates, etc?
Yes. Regulin works across different breeds and while the average response is 20%, it can be lower or higher depending on the breed or joining date. While less seasonal sheep will advance into early October more traditional English breeds or composites with predominantly British breed influence will only advance 8 weeks from their normal peak joining period.
Are there specific breeds that have shown to benefit more from implanting Regulin?
Regulin works well in all breeds of sheep including composites and Merinos. We are happy to provide you with free advice tailored to the needs of your sheep and your breeding program.
2. Regulin in 3 in 2 or year-round programs
Has anyone been successful in breeding composite ewes 3 times in 2 years with Regulin?
Yes. It’s common. Regulin is only needed in the Spring and Early Summer joinings, however care needs to be taken especially if joining before October. Our technical manager is happy to provide tailored advice on the program design.
I’ve got a few producers looking to lamb year-round how would they recommend we use Regulin in these systems?
We have specific recommendations for year-round joinings/lambing and as above we are happy to provide individual consultation to tailor a program to the farm operation.
3. Fecundity
Are there circumstances where Regulin increases fecundity but does not significantly increase conception rates?
Yes, but not very often. If the ewes are able to express oestrus, but not able to reach their full genetic potential, then Regulin will increase their fecundity.
What is the effect if any of Regulin on ewes that already have a high rate of multiples?
It can tighten joining up and bring it forward, however it depends on the rate of multiples for the breed and the time of year they are joined.
4. Cost and Return on Investment
Why is Regulin so expensive? Does it have a patent that will run out one day? Does anyone else make it?
Regulin is roughly the cost of a kg of lamb. When measuring outcome against cost the return on investment is heavily in Regulin’s favour. Melatonin itself is not patented but Ceva has the only technology to manufacture a slow-release implant.
The company sets the priced based on the costs of R&D and bringing it to market, which are very high in Australia due to the strict regulatory framework.
Combining the performance increases discussed, what is the $ value to sheep producers?
On average over a five-year period, Regulin users get 20% more lambs on the ground than if they hadn’t used it. Results can vary from year to year depending on weather, feed and management. The results depend on how many ewes in your flock you treat and how well you look after them. As one of our farmer ambassador says: “You do the maths”. You can get a good idea on your expected returns at www.regulin.com.au/ready-reckoner
5. Using Regulin in ewe lambs
In the ewe lamb trial with teasers – when were the teasers put in and for how long?
The teasers went in on 2/1/24 and came out 14 days later on 16/1/24 when the rams went in. (Ed. There was a typo in the presentation.)
What was the joining date of the CSU sheep both adult and ewe lambs?
Rams were introduced on 16/1/24 for all groups of ewes in the study, whether or not teasers had been used.
How old were the ewe lambs in the trial? 6-7 months, 10 months or rising 12 months?
(Bruce) the ewe lambs were born in June/July and implanted in January February. So only 6-7 months, which is why perhaps we didn’t see as much of an effect as we anticipated.
Could Lydia give a reason why teasers didn’t have more of an effect on ewe lambs?
The research and analysis are still ongoing, but the question is really beyond the scope of this project. It’s possible that because ewe lambs are not usually in oestrus for as long as mature ewes or demonstrate it so clearly (always a challenge in ewe lambs). Full rams obviously have the benefit over teasers in being able to impregnate a ewe lamb when she’s cycling even if there are weak signals and due to her inexperience.
Would using Regulin in ewe lambs mean we could join earlier, at say 7 months of age?
Regulin only works in ewe lambs who are sexually mature. It does not advance puberty. Generally, ewe lambs need to be 45kg in weight and have lived for a Summer to sexually mature, ie. able to achieve oestrus. Ewe lambs born in Autumn can normally join the next the next Autumn at 11-12 months old, whereas lambs born in Spring can also be joined the following Autumn at 6-8 months old. See more in Russ’ presentation on joining ewe lambs at www.regulin.com.au/ceva-university
Russ – on the puberty topic, am I correct in assuming that using Regulin to bring ovulation/joining forward and tightening joining periods could result in subsequent ewe lamb groups being more uniform in reaching puberty and better percentages in joining?
Yes, as they will all be roughly the same age and weight, the key driver of puberty. Lots of research has been done on this.
If we are breeding a very seasonal ewe (Wiltipoll) with a non-seasonal ram (SheepMaster) and their progeny are born in the spring, will using Regulin help joining percentages in the ewe lambs in November for an autumn lamb?
We don’t recommend treating any ewe lambs with Regulin before the end of December. Wiltipolls X SheepMasters, which contain genetics from a wide variety of very seasonal and less seasonal breeds, so it is unlikely any ewe lambs joined in November will achieve effective results. Please contact our technical manager for specific advice.
6. Regulin in rams
I have a client using Regulin in his rams only, what are your thoughts on this practice? Is he wasting his time by not using it on his ewes as well?
No, however he will get a far better return if he follows the complete protocol. Regulin was originally designed for ewes and the ram work came later, which is when we extended the registration. If you treat only the rams, you’re likely to get a 5% increase in lambs the first year and a compression of lambing by one week. Results in following years vary. There will always be a positive response, but not up around the 20% we know you get when ewes and rams are treated.
If using lupins to increase sperm production in rams, would Regulin add to this further?
Yes. But given the cost of lupins and the associated workload in feeding them specifically for sperm improvement, have you considered a simple Regulin program?
Is there a risk of greater heat stress on rams treated with Regulin if we ramp up their sperm production by 50%? Are larger testes harder to thermoregulate / keep cool?
No. Regulin is registered for its ability to increase the amount of sperm per ejaculate and the evidence suggests that Regulin reduces the impact of heat stress in rams, it does not exacerbate it.
Is there any refractoriness [sic.] with repeated use of Regulin?
One of the key objectives of the Sydney University research was to investigate the possibility of refraction. Those findings are supported by multiple studies including the MLA BL research at SARDI, which showed the opposite, ie. that rams implanted for out of season joining out-performed their non-implanted control counterparts in the following breeding season.
Can you expand on the reasoning behind giving 3 doses of Regulin to rams? What are the benefits to ram performance, semen quality, etc.?
Rams are predominantly heavier than ewes so require more melatonin. Research has been conducted into various numbers of implants for rams from 1 to 5. Three implants provides the most consistent and commercially-economical response across the broadest range of breeds and weights.
With consideration to the effect of heat stress on rams and the benefits of Regulin with respect to semen production and performance, would it be beneficial to implant rams with Regulin prior to late summer/early Autumn Joinings (where ewes have not been implanted)?
Evidence would suggest it could be possible, however Regulin is only registered to increase sperm in advanced joinings.
I have Border Leicester rams and they never appear to be doing any work. Are they seasonal? Would Regulin have any effect on them?
Yes BLs are very seasonal. Melatonin is at its peak at night and therefore joining is likely to occur during the night; but famers have reported that when Regulin is used in BL rams, you certainly see daytime mating behaviour.
MLA has published a paper on Border Leicesters which is available here https://www.mla.com.au/extension-training-and-tools/search-pds/pds-data/border-leicester-rams-into-action/
7. Heat stress and climate change
Megan – “Is a heat stress event defined as hotter than 32 degrees in the week of joining or during all of joining?
Any day over 32ºC in week prior to joining or during joining can impact a ewe’s ability to get pregnant.
Megan – were the producer groups concerned about heat stress and climate change impacting their production capacity in SA?
(Megan) We’ve had very dry year in SA and we had many producers keen to participate in the trials and hear the results. Farmers are concerned about heat stress and how it affects their sheep in terms of reproduction, but also in terms of water usage, mounting behaviour and so on.
(Bruce) We are very frequently asked about on the effect of heat on rams and ewes during joining and over the past 4-5 years there has been an increasing concern among farmers on increasing temperatures ie. climate change. Measuring the difference on joining results from year to year is extremely difficult.
8. Novel (off label) uses of Regulin
I’d like to know more about the effects of Regulin pre-lambing for increased survival of twin lambs.
The research indicates that Regulin implanted in a twin-bearing ewe during pregnancy increases the vigour and likely survival of the second-born lamb. This was replicated in a University of Adelaide trial in a number of sheep a few years ago. Significant other trial results have been carried out around the world and the results are available on the internet.
Federico mentioned implanting lambs at 30 days of age. Will consumers be happy with this? Even though melatonin is natural, consumers react to exogenous hormones. We can get away with treating ewes and producing better lambs but treatment of lambs seems problematic.
Regulin is not licensed for use in lambs. The research data is strong, however a business case for commercial use would need to be established. It’s worth a mention that there is no withholding period for milk or meat using Regulin in adult sheep.
Does the colostrum quality data mean we can assume that ewes lambing in autumn/winter would have a naturally higher quality colostrum due to decreased day length?
No. The studies have focused on whether Regulin elevates the levels of colostrum during lactation against control groups. Which it does, regardless of breeding season.
9. Miscellaneous
Do we know what effect altering melatonin levels with Regulin has on other, non-reproductive systems in the body, but which may indirectly alter reproduction eg. drive to eat, sleep wake cycles, digestive function, energy storage and utilisation by the body?
Implanting Regulin simply advances the breeding season, it does not exceed the maximum amount of melatonin than a sheep would ordinarily produce in Autumn.
In all the European studies the sheep were joined in Autumn except in Spain when they were joined ‘out of season’. Regulin hasn’t been shown to affect any other function and there is no difference in the cohorts joined in or out of season.
Why doesn’t the Regulin website have the research papers available anymore? How can we get copies?
Due to Copyright reasons, we were asked to remove the links to and papers from our website. Some are available free online by the publisher, please contact us if you would like copies of any particular papers listed on www.regulin.com.au/references
In horses there is the use of light either in stables or using masks that shine lights into the eyes that alter cycling and winter coat development. I understand this is not commercially viable in sheep but has this method of altering melatonin levels been trialled in sheep?
Yes there’s been lots of research using artificial light sources to induce oestrus in sheep (day length), but it’s not as simple as turning the lights on and off. The variation of day length and intensity of light provided (lumens) are factors. Please contact our Technical Manager for more information.
Dairy and Boer goats: results in maidens, dry goats, lactating goats at different stages times of year?
There has been significant research on Regulin in goats. See our references page or contact our Technical Manager for further information or copies of the papers.
Here’s a list of questions our team members get asked often. Please feel free to contact us for further information about your own flock or individual requirements.
What is Regulin®?
Regulin is a melatonin implant that improves the reproductive performance of sheep in spring and early summer for increased lambing percentage.
What does Regulin do?
Regulin increases the melatonin plasma level in blood and creates the fertility response in sheep that you would normally expect in autumn.
When can I use Regulin?
It depends on the breed of your sheep but generally for Merinos and Dorpers you can use it from September to January. For British breeds, the earliest joining period would be mid-January. However other options may be available please contact us for advice on your particular situation.
Does Regulin have a withhold period?
No, there is no withholding period in sheep for milk, meat or offspring.
Can I just treat my rams?
While Regulin increases the reproductive performance of rams, the best results are obtained by treating ewes and rams. If you only treat your rams, you can expect – at best – a 5% uplift in lamb percentage in the first year, mostly due to the ‘novel ram’ effect. You can also treat your rams only, if you just want to compress your lambing by a week.
Can I use Regulin on maiden and ewe lambs?
Yes, but both must be in good condition and sexually mature. A Body Condition Score of 3+ is recommended.
What is the difference between Ovastim® and Regulin?
There is a detailed technical note on the difference between Regulin and Ovastim but the basic differences are Regulin is used to increase fertility in out of season joining and Ovastim works for in season and is not recommended for use in Merinos.
Can I use Regulin on lactating ewes?
Yes, but the best results will be achieved if the ewe is at least 30-40 days post-partum and has weaned the lamb prior to joining.
How do I administer Regulin and where does the implant go?
Regulin is implanted under the skin at the back of the base of the ear using the specially-designed applicator (sold separately).
When shouldn’t I use Regulin?
There is little research to show a positive return after March. We don’t recommend to use when Body Condition Score is lower than 2.5.
Will Regulin affect the fertility of my sheep?
No. Regulin will not affect the genetic capability of ewes or have a detrimental effect on their fertility.
Will Regulin produce more triplets?
The normal response of Regulin is to replicate the genetic capability of the ewe. If this is a twin then she will twin, however the triplet rate of 1-2% is normal in most flocks.
Does Regulin mask genetic infertility?
No. Regulin will not cure infertility. Dry ewes should be separated from the mob after scanning for culling or putting into the next joining.
How long does Regulin last?
Regulin releases melatonin for about 100 days. Implanting 40 days prior to joining means the vast majority of ewes conceive in the first or second cycle during joining.
What is the shelf-life?
Regulin is stable for 4 (four) years when stored below 25°C in air-conditioning if necessary. It should not be refrigerated.
Is Regulin safe?
Regulin has been used safely in sheep in European countries including Spain, Greece, Turkey and France for many years. Click below to download the Safety Data Sheet.
For more information about how Regulin can help boost the productivity and profitability of your sheep enterprise, call 1300 6999 16 or use the contact form below and we'll call you.
Regulin® is licensed for use in ewes and rams in Australia by Ceva Animal Health.
Ceva has collaborated with scientists and veterinary practitioners to further knowledge of sheep and goat reproduction. Results have been published in leading academic journals.
Ceva’s commitment to educating veterinarians working with small ruminants also includes the launch of www.reprology.com which gathers all available data and publications regarding reproduction in cattle, sheep and goats. The use of melatonin (Regulin®) as a reproductive tool is one of the company's latest contributions in this field.
Ceva is a global company. It has offices in 45 countries and works in more than 110. It has 12 R&D centres, 25 production sites and more than 5000 employees worldwide.
Ceva Animal Health Pty Ltd. 11 Moores Road, Glenorie NSW 2157
T: +61 2 9652 7000 | F: +61 2 9652 7001 | W: ceva.com.au
