IMPROVING CONCEPTION IN A FLOCK
WITH A HISTORY OF LOW CONCEPTION RATES

by
Martin R. Dally
Super Sire, Ltd.

If a flock has a history of low AI conception rates, the following steps may help improve conception rates.

1) Sixty days before inseminating have blood samples taken from a representative group of ewes in order to have the trace mineral and vitamin status determined. Trace minerals of concern are selenium, copper, cobalt and zinc as well as vitamin E level. Any deficiencies should be corrected as soon as possible.

2) Forty-two days before inseminating, ewe should be condition scored. Any ewes that are found to be in condition score 3 or lower should be supplemented at a rate that will ensure that they reach scores of 3.0 to 3.5 at time of sponging. If ewes are in condition score 4 and higher, it might be wise to lower their plane of nutrition in order that they are condition score 3.0 to 3.5 at time of sponging.

3) It is highly recommended that all ewes being inseminated be vaccinated to prevent abortion-causing disease at least 4 weeks before AI. Contact your local veterinarian for vaccination recommendation.

4) Put teaser rams in with ewes at least 4 weeks prior to sponging. Equip the teaser ram with a marking harness. During the 4-week period a significant number of ewes should be marked. Ewes that have been marked indicate that they are naturally cycling and therefore should respond well to the hormone therapy. If at all possible, only ewes that have cycled should be used in an AI program. If non-cycling ewes are to be inseminated, it is recommended that a higher level or PMS-G be given to these ewes.

5) Double sponging extremely large ewes at the start of the breeding season can improve conception rates of these ewes. An alternative to double sponging is to re-sponge ewes on day 7 of the hormone therapy with a new sponge.

6) Placing a teaser ram in with the ewes after sponge removal and only inseminate ewes that have been marked. This will eliminate any ewes that did not respond to the hormone therapy.

7) It is extremely important to minimize stress of the ewes during the hormone therapy program as well as the first 32 days after insemination. Dogs should never be used to work the ewe and any unnecessary movement of the ewes is strongly discouraged. Heat stress can affect conception rates; therefore the ewes should have access to shade and clean water at all times.

8) Feeding high levels of concentrates after inseminating has been reported to cause lower conception rates. Therefore it is recommended to decrease the level of concentrates being fed.

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