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SHEEP HEALTH - BREEDING


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GETTING YOUR EWES INTO SHAPE FOR BREEDING


By Ian McDougall BSc, MRCVS, BVMS

A. Pre AI or mating day.

1. Early Breeding Flocks and the "Ram Effect"

Most farmers breed their ewes early in the natural breeding season. As a consequence these ewes may not be cycling naturally by your AI or early tupping (mating) date.
However, we know that if there are an increased number of ewes cycling naturally before sponging, we can expect a more successful synchronisation and conception rate.
To increase the number of ewes cycling naturally, we use the RAM EFFECT as described below.

The Ram Effect causes ewes that have had no previous sexual contact (physical, smell, sight or sound) with a ram this season to be naturally induced to come into season following the addition of a male teaser (vasectomised ram) to the group even a randy wether will do. This induced oestrus is reasonably predictable and synchronised. Once started, the ewes should carry on cycling normally. This is just what is wanted.

Method

  1. Immediately after weaning or drying off your ewes or even if you keep milking them, keep them as far as possible away from any sexually active males (for Frieslands this can also mean quite small ram lambs) and this includes billy goats as well!
  2. Next introduce the teasers 4 weeks prior to the intended AI or tupping date. They should be of a type with increased early season libido and be thoroughly randy. At least one teaser should be introduced to every 25 ewes. Note It is essential that the vasectomies are carried out on the rams earlier in the year by your Vet to allow the animal to recover and for any semen present in the system pre-operation to be removed. Always get your Vet to check the vasectomies before each season for the best success.
  3. Two weeks after the introduction of the teasers, insert sponges as per your programme and remove teasers. Take great care in inserting the sponges so that no damage is done to the ewe. If you have not done it before, make sure you get someone to show you how to insert them properly.
  4. Put in the rams or AI fourteen days later.

2. Feeding

At the time of mating ewes should be fit, but not fat. This is usually not a problem with dairy ewes, but some breeds, especially if they have been weaned early do put on extra condition. They are better on the lean side. However if not still in the parlour, they should be pushed on a little from one month prior to the mating date to give the increased plane of nutrition and "flushing" effect that is wanted .

3. Management

Any tasks associated with the ewes' management should occur about one month prior to the mating date such as weaning, shearing, health tests, feeding trace elements or giving multivitamins. Try to reduce the times the flock is handled out of the normal routine of milking or moving from field to field. Avoid all stress.

4. Previous Conception Rate Problems

Any flock that has had previous problems with ewes not holding to AI or first services should have the VitE/Selenium status investigated. Sub-optimal levels of VitE/Selenium have been implicated in this condition.

B. At AI or tupping

  1. Clearly identify the ewes either by ear tag, tattoo, ear notch or paint spray. Make sure the identity is easily legible.
  2. Handle ewes patiently and keep stress to a minimum.
  3. If using sponges, tease ewes efficiently every 6 hours from 24 hours after removal of the sponges
  4. When specific ewes have to go to a specific ram, make sure that the first ewes presented for AI are also the ewes that came into season first.
  5. Ewes for AI will have had to be on a restricted diet with no water for 24 hours before being inseminated, so make sure they have some hay ready for them after they have been inseminated before they go back to their pasture, do not put them on to new pasture and do not over feed. DO NOT FEED CONCENTRATES IMMEDIATELY.
  6. Make sure they can get a drink of clean water directly after being inseminated. This does not apply to ewes being put with a ram as they do not require to be restricted in any way prior to being mated.
  7. Try to avoid any form of a stress situation for the ewes from the day before to 4 weeks after mating or insemination. This includes moving or "dogging" the ewes or any other management task involving handling them.
  8. If this is your "first" time doing an AI programme phone the AI team well in advance of your chosen AI date to consult them as to their requirements. Remember it is a busy time for both farmer and Veterinarians so try and help as much as you can yourself by telephoning and having any questions ready to ask.

C. Post AI or mating.

  1. Chasing ewes. When using AI early in the season some ewes will return to oestrus 5-7 days after being inseminated. These can still be got in lamb with the bunch if you add either the ram you were using or a fertile sweeper ram in with them. He must wear a raddle to indicate which ewes have turned.
  2. Do not let your ram "overwork" himself by turning him out with the all the ewes that have been synchronised and inseminated unless it is a very small bunch. Better to divide them up into small groups with a ram in each. Ram overwork is a common cause of injury and ultimate death. This is particularly true when using ram lambs .
  3. Keep the ewes on maintenance feeding levels only for at least 4 weeks after mating.
  4. Remember that any ewes returning to oestrus will remain well synchronised over the return periods i.e. 15-19 days after mating. Your sweeper/chaser ram will need to work hard during this period so make sure he is capable of this, i.e. an older ram. At least one chaser ram per 30-40 ewes will be needed after using fresh semen for AI and one chaser ram per 20-25 ewes following the use of frozen semen.

    NB. The most common cause of multiple returns after AI is over work in the ram. He gets over tired and temporally infertile. He simply cannot "get round" all the ewes at the same time.

  5. Scanning: If you inseminate early in the season, all ewes not returning to AI should be scanned 30-40 days after insemination. This allows identification of potentially "barren" ewes which have not held to AI and yet have not returned to oestrus post AI. This is as a consequence of the early season and the effect of sponging.

    NB This is especially important following widescale use of frozen semen where a decrease in conception rate is seen in comparison to fresh semen use. If ewes are found not to be pregnant, they should be returned to oestrus immediately either sponges can be used again or prostaglandin. Consult your Vet. Extreme caution should be taken when using prostaglandin, any inaccuracies at scanning may result in abortion. This is not the case when using sponges with PMSG in pregnant ewes.

  6. Lambing: Your ewes holding to AI will lamb over a 4-5 day period with a peak around day 145. Remember the point of synchronising the ewes is that they will all lamb as a group. Be sure you have sufficient labour lined up, pens made, drugs etc in hand and arrangements for the lambs if they are to be artificially reared, especially frozen colostrum and heat lamps.


  7. Results: Keep careful records of lambings, ear tags, losses, and any other points of interest for discussion later.
    Good Luck

(From Sheep Dairy News Vol 15, No.2).

RAM PREPARATION GUIDELINES

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