Dr. Todd Bickett
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DONOR SELECTION28-Sep-2009

Obviously the most important thing necessary for your involvement in embryo transfer is selectio..

DONOR SUPEROVULATION28-Sep-2009

Superovulation is the process utilized to force your donor to produce multiple ova to become fer..

MANAGEMENT OF DONORS AND RECIPIENTS28-Sep-2009

**Successful embryo transfer programs require intensive management and attention to detail. The ..

RECIPIENT SELECTION28-Sep-2009

Although not as critical as the donor selection in terms of your operation, it does not lag far ..

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RECIPIENT SELECTION

28-Sep-2009

Although not as critical as the donor selection in terms of your operation, it does not lag far behind the donor in terms of the success of your ET program. It does not make sense to choose potential recipients from the bottom of the cow/calf sector. Why place the most valuable progeny you may produce to the least proven or productive cows? That point being made, the ideal recipient does not differ from the ideal donor. I would prefer a 3-8 year old recipient that has calved annually and that has calved 60-90 days prior to implant.

 

What about heifers? In the earlier years of embryo transfer, I would have said this was ideal from the embryologist standpoint to maximize pregnancy rates but maybe less ideal in terms of a heifer’s ability to achieve acceptable weaning weights on the calves for the producer. Over time, I think this situation has evolved for various reasons to the point now that I would place heifers near the bottom of the selection chain. It seems these heifers are less predictable in their pregnancy rates and seem to incur more failures than mature cows. Some of the fertility issues possibly being involved in those situations could include cyclicity of those animals, growth implants, nutrition (over conditioned and under conditioned) as well as factors we have yet to identify. If, however, that is the animals you have to work with, they certainly can be useful with the understanding of the stated risk.

 

First calf heifers are also commonly used as recipients. Typically, these are the most difficult animals from a producer standpoint to get pregnant in natural service herds. It stands to reason that they would be the most difficult to get pregnant in embryo transfer. I do believe that is strictly a nutritional issue and very successful pregnancy rates can be achieved in the level of nutrition is increased in this set of cows.
 

 

Lastly in the recipient pool are the open cows of unknown origin with the most common source being a sale barn. These are obviously last on my list. My comment to most producers is typically “why do you think they are in a sale barn?” One exception to that comment occurs with a group of mismanaged first calf heifers that never had a reasonable opportunity to become pregnant on the farm. Under proper management and time, they have worked very well.


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