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Joining percentages for rams and ewes

Young, healthy rams that are joined under the best conditions are capable of successfully serving large numbers of ewes. However, using too many rams at joining can be counter-productive and cause competition between rams as ewes come into heat. It's a good idea to limit the number of rams to the minimum needed. This will help you achieve maximum conception during a relatively short, controlled joining.

You can take steps to ensure the maximum productivity of your rams, including:

  • turning over around 20% of your ram flock each year (keeping them for 5 joinings or up to 6 years of age)
  • running them at half the stocking rate of other dry sheep
  • shearing rams twice a year
  • giving supplementary feed
  • providing close supervision and care
  • when necessary, drenching, jetting, and vaccinating.

Factors that influence joining percentage

Rams that are in good condition, well nourished, disease-free, physically fit and joined under ideal conditions will be capable of successfully serving large numbers of ewes. However, the health of your rams is not the only factor that contributes to the success of joining.

Paddock size and waters

The size of your paddock as well as the number and location of watering points influence how well your ewes and rams mix together during joining. Larger paddocks with multiple water points will need more rams in order to increase the probability of adequate ewe-ram contact.

Ovulation patterns of ewes

Large numbers of ewes will often cycle over very short periods of time. This can occur naturally in ewes joined between March and the end of May, or it can be artificially managed by using the ram effect. Although it's desirable to have ewes cycling over short periods, there must always be enough rams present to ensure a high level of conception is achieved at each oestrous peak.

During a 10-week joining, ewes will have the opportunity to cycle up to 4 times. Mature ewes will only be in heat for about 24-36 hours at each cycle, while maiden ewes may cycle for as little as half an hour at a time. If the percentage of rams is too low, many ewes will not be served and, in the case of 'out of season joinings', may not exhibit normal oestrous at their next cycle. An out-of-season joining refers to joining at any time other than March to the end of May.

Desire, ability and stamina of rams

Although rams with physical defects can be identified and culled, factors such as desire (libido), mating ability and serving capacity (stamina) are more difficult to measure. There is often a considerable variation in these factors between rams within your flock. As a result, the joining percentage needs to allow for those rams that will not successfully mate with their allocated number of ewes.

Optimum joining percentages

The optimum joining percentages for rams and ewes vary at different times of the year:

  • Autumn joining (March-June) - mature ewes 1.5% and maiden ewes 2%.
  • Other joining times - mature ewes 2.5% and maiden ewes 3%.

Maiden ewes are only in heat for a short period of time at each ovulation and may also exhibit irregular oestrous activity. This means they need a slightly higher percentage of rams (an additional 0.5% of rams).

These joining percentages will be sufficiently provided if:

  • nutrition is adequate
  • the ram flock is young, fertile and healthy
  • paddocks are not too large.

If you cannot meet these requirements, a slightly higher percentage may be needed; however, you should regard 3% as the maximum required.

Competition from too many rams

Using too many rams can be just as counter-productive as using too few. It can result in excessive competition between your rams as the ewes come into heat, which can have a negative effect on your conception rates.

Keeping rams back

The practice of keeping some of your rams back and putting them out towards the end of joining is not necessary or effective in most circumstances. It's important that the correct ram percentage is used right from the start of joining, because that is when the bulk of your ewes will be cycling.

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