It is once again time to start planning for the next year’s lambing season. The first step should be in determining when you want the ewes to begin lambing and counting back the 147 days which is an average gestation. The success of the next years lamb crop actually begins prior to the breeding season. The rams need to be in adequate body condition because they will lose weight during the breeding season. Having a ram breeding soundness exam done is a good suggestion. The ram breeding soundness exam should include an overall physical exam of the ram as well as a semen collection and semen evaluation. In smaller flocks that only have one or two rams this is more critical, because if one ram is infertile or has an inability to breed a ewe it will impact an entire lamb crop. In larger operations often a ram's poor performance is masked by the other rams. Purebred producers who wish to make specific matings with a group of ewes to a particular ram, should follow the next heat cycle with a proven stud to prevent a large number of ewes from being left open. The use of a marking harness is an excellent tool to help identify problem rams or recycling ewes. Purebred breeders or small flock owners who wish to keep track of matings should place a marking harness on their rams starting out with a light color such as yellow. Then every 17 days switch to a slightly darker color such as orange, then red, then blue followed lastly by a dark green or black. If you wish to switch rams then you can also record if a ewe remarks and to which date a particular ram mounted her. If you keep a written daily record of the activity you can also use this information at lambing time to help identify which ewes are near lambing.
Rams also need to be wormed and have their feet trimmed prior to the breeding season. It is also a good idea to begin flushing the rams with some grain prior to the breeding season if you do not already have the rams on a diet containing some grain. They should not be in full fleece, if you shear prior to turning out with the ewes in the summer make sure to use a fly control product such as Delice. Avoid turning out ram lambs into large pastures or mixing them in with a set of older rams. Ram lambs have a tendency to be well fed and used to getting a high quality diet. If they suddenly get placed out on a pasture with only a "water hole" and salt feeder they can look quite different in 2 to 3 weeks. Combine their diet change with some older dominant rams competing for the same ewes and the ram lambs quickly become statistics.
Handling the ewe prior to the breeding season is essential to your program’s success. There is a lot of literature written on this particular topic and well worth your time to read and understand. Unfortunately we are going into this breeding season with a limited choice of abortion vaccines. Colorado Serum Company has a license on their Campylobacter Fetus (Vibrio) Bacterin which is a 5cc product given 2 weeks prior to breeding and boostered in 60 to 90 days for first time vaccinates. Previously vaccinated sheep need only the annual booster prior to breeding. High risk flocks that have a history of vibrio abortion or flocks that make new additions should always revaccinate at mid gestation. The Colorado Serum product is an aqueous suspension of inactivated (killed) cultures of Campylobacter fetus sub sq. jejuni and intestinalis with aluminum hydroxide as an adjuvant. Colorado Serum has also been working on getting a Chlamydia vaccine released, but it is not available at the present time and we do not really expect to have it prior to the breeding season, however we continue to be optimistic that it will eventually be released.
Prior to breeding is a great time to worm the ewes with a product that will also get tapeworms such as Valbazen, Panacur or Synanthic. The products that are effective on tapeworms also have a risk to pregnant ewes and we prefer not to use them during gestation. Many producers also take this as an opportunity to do a final culling on any ewes that are excessively thin, lame or have lumps in their udders. Make sure that there is plenty of salt available, we recommend using additional selenium and Vitamin E during this period and again prior to the lambing season.
J. D. Bobb, D.V.M.
International SheepLetter
Vol. 18 No. 5, August 1998