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Country: Ireland

Source of information: Teagasc (






Just Being Tested


Aim: To naturally synchronise ewes and compact the breeding season


  • The ram effect:
  1. can be used to induce the onset of oestrus cyclicity in adolescent (<1 year of age) and mature ewes, once they are sufficiently close to the onset of normal cyclicity.
  2. causes the onset of cyclicity through the release of pheromones from sexually mature rams. The onset of oestrus in adolescent ewes generally occurs at a later date compared to mature ewes.
  • The time table for implementing the ram effect is presented in Table 1.
  • When implementing the ram effect rams can be prevented from mating ewes by being fitted with an apron.

Table 1. Time table for use of the “ram effect”




Introduce aproned rams


Remove aproned rams


Introduce fertile rams


1st peak in matings


2nd peak in matings


  • After the introduction of rams the majority of ewes that have not entered their breeding season will have a silent heat within 36 hours and some will have a second silent heat after 6 days.
  • Ewes will cycle approximately 17 days after their silent heat resulting in two peaks in ovulation at approximately 18 and 23 days post ram introduction.
  • Fertile rams should be introduced to the ewes 14 days after initial introduction to allow for variation in cycle length and  for ewes already cycling when aproned rams were introduced.

Expected benefits:

  • Approximately 75% and 90% of ewes will lamb in 2 and 3 weeks, respectively.

Prerequisites and/or limits:

  • Ewes must be out of sight and smell of rams for 4 weeks prior to implementing the ram effect.
  • Additional rams are required (approximately 1 ram per 30 ewes).
  • Additional labour and facilities (e.g. lambing pens) are required at lambing.

Scientific basis:

Walkden-Brown, S. W., Martin, G. B., & Restall, B. J. (1999). Role of male-female interaction in regulating                                   reproduction in sheep and goats. Journal of Reproduction & Fertility. Supplement, 52(FEBRUARY), 243–257.

Rosa, H. J. D., & Bryant, M. J. (2002). The “ram effect” as a way of modifying the reproductive activity in the ewe.                       Small Ruminant Research.

Hawken, P. A. R., Evans, A. C. O., & Beard, A. P. (2008). Short term, repeated exposure to rams during the transition                     into the breeding season improves the synchrony of mating in the breeding season. Animal Reproduction                         Science, 106(3–4), 333–344.

Keady, T.W.J. 2016. It’s all in the breeding. Irish Farming Independent. 30 August. Pp 8-9


Tips and Tricks:

The ram effect

Anti-mating apron for rams

Ram chest crayon marking

Harness with crayon

Melatonin implants

Measuring tape to assess the testicular perimeter of rams


Level 1 assessment: 

Benefit expected Fertility
Less workload
Better labor organisation
Better feed management
Less stress for the farmer 
Is the solution suitable for various production systems Y
If no – for which system              
What are the asset costs <100
What are the maintenance costs <50
Any limits to its applicability Ewe out of sight and smell of rams for 4 weeks, additional ram power, and additional labour and facilities at lambing
Work Load
  Farmers Service provider/tech.-vet-others
How much time is required to prepare and implement the solution < 1 day  
How many people is needed to implement the solution?  One  
How long it takes to get results? > 1 week
How long it takes to see  an effect on sheep productivity? Current production period
  Farmers Service provider/technicians-vet-others
What kind of equipment/tool are necessary? Anti mating apron for the ram during the 2 days of teasing
Skill/Knowledge-Training (farmer)
Does the solution need any specific skill/knowledge or training? Knowledge of the ram effect calandar
How much time will be required for training < 1 hour
Wider Environment
Is there any particular regulation link to the solution? No
Does the solution need any particular structure or organisation? No



Level 2 assessment: 

Solution name: Use of the ram effect to compact the lambing season

Country: Ireland

Level 2 assessment:




Solution No/Name

 6/Use of ram effect to compact the lambing season

Farmer/Service provider/technicians-vet-others



Why did you select this solution?

 To compact the lambing

Was it easy to implement?


If not say what are the identified drawbacks?


Did you need to adapt it?


If yes, how?


Were you happy with the outcome of the solution?


What were the outcomes?

92% fertility

Score the solution

Interesting and easy to implement

Will you continue to implement it?


If not, for which reasons?



 If there is enough lamb, everything is perfect. What if the rams stay 20-30 days in order to make sure the 2. cycle to increase the fertility ?


As stated in the solution, more “ram power” than normal is required as a lot of ewes cycle together. If inadequate ram power is used then the lambing season could be extended rather than shortened.



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