EMBRYO TRANSFER - IMPROVING BOVINE PREGNANCY RATES

Unacceptable low pregnancy rates can be due to poor management practices of donors and recipients and not the often expected poor embryo technology.  The most common practices causing stress can be divided into, incorrect condition of donors and recipients, transportation problems, rough handling of cattle, inadequate management of liquid nitrogen tanks and their contents, and unfortunately unknown causes.

When synchronizing recipients using the two shot prostaglandin (PG) system and only 30-40% show standing heat, that is the time to cancel the program. Usually after the second shot only 50-60% respond.  In addition when those relative few recipients are implanted pregnancy rates are unacceptably low. These results are due to the demise of the corpus luteum (CL) by Day 21. Results such as these can be backed-up by a published study of Kunkel et al in Theriogenology in which pregnancy rates after artificial insemination are related to the physical condition of the cattle. For instance cows rated as a body score of thin #3 achieved a low 43% pregnancy rate,  a #4 only  achieved a 61% pregnancy rate, and  a #6 achieved a very good 93% pregnancy rate, but as a fat #8 pregnancy rate was down to 50%. How many times are we presented with poor quality recipients, sometimes the rejects from the usual breeding program?

Shipping recipients immediately after transfer does not influence pregnancy rates. We had a chance to study this situation in our program at CSU. One client transported his donors and recipients from southern Colorado to Fort Collins, a 10 hour drive, while he slept we worked on his animals all day collecting and transferring embryos and then that night they were shipped back home. We compared embryo collection numbers from the donors and the pregnancy rates in the recipients to our resident donors and recipients and there were no significant differences.

Rough handling of donors and recipients will also yield poor results. This is thought to be due to increased release of cortisol, a stress hormone, which adversely affects other reproductive hormones leading to lower embryo collection rates, decreased quality of embryos, and lower pregnancy rates.

Another factor leading to disappointing results can be the management of liquid nitrogen tanks and the handling of frozen semen canes and straws. Considering the total costs of an embryo transfer program it is wise to evaluate the spermatozoa even if you just look for movement of sperm in a drop of the semen using the embryo stereozoom microscope itself. With these kinds of microscopes individual sperm cannot be observed, but in most cases out in the field movement is all that can be accomplished. Examples of damaged sperm can be excessive exposure of frozen straws when either changing tanks or selecting straws to use.                               

Good Luck!

-Dr. Peter Elsden
www.ETschool.com

Thank you Dr.Elsden.
I'm new on the ET technology, already made 6 flushes on my donors, and some times we feel so "desarmed" with this process of ET. On my last flush, on march, I put 10 donors on flush (7 Shorthorns, 2 Herefords and 1 Galloway belted) got very few embryos and 5 cows produced none frozen embryos, by the way one donor produced 34 estructures and another one more 33 estructures, all with degenerated embryos.
Reasons, don't know, maybe the drought, not severe, but not enough rain for 90 days. Maybe high CC donors with 4 to 5 score donors (1-5 score).
By the way, will restart my program n next september, winters end here in south hemisfere.
Will take a look more accuratelly on your comments.
Thank you.

Have found here that the environment seems to play the biggest role in embryo survival;
it seems to be something we cannot predict nor control well at all; such as, last August we transferred
embryos and one would think that the heat of the late summer would have been killing to them; we got our
best conception of the year, because (we believe), it began to rain shortly after the embryos were put into
the receipts and the grass was growing again. 
When putting in embryos for fall borns, we have found that if we get a big shot of very cold weather shortly after implant, that cuts
back the conception drastically.
It seems to be alot of environmental factors in that the cow's body is thinking it is or is not OK to have the added stress
of pregnancy on their bodies.
We use nothing but calm, docile cows for receipts because of the stress factor on conception.

Thank you for your input.

We have been doing the ET work for a number of years now with very large numbers and have been working towards higher conception rates each year and here are just a few different practices we follow that have definitely improved our number of settled pregnancies drastically.  1.) Similar to what was said in the top post, hauling the cattle can have a major influence on the recipients or any bred cow.  We follow the rule of the "No Haul Zone" days 10-45 after they are bred we never haul a cow unless absolutely necessary for another reason.  At day 10 the embryo begins attaching to the wall in the cow and is very susceptible to being aborted if stressed during this time.  This makes the window to haul your recipients after you implant the embryos is very tight; 3 days since they cycle one week before.  We have seen significant improvements in many herds if this practice is used.  2.) Proper mineral program.  One this easily forgotten about is the need for a mineral program year round in all herds but more importantly during the time from after calving thru breeding.  The needed trace mineral needed by mature cows can be a big deciding factor in conception rates.  One product that has shown to be beneficial for us in the Mulit-min 90.  We have gave every cow on the place this supplement 45-60 days prior to breeding and have seen 5-15% bumps in conception depending on the herd.  3.) Condition of the cows at time of breeding.  This was mentioned before but it is definitely the most important factor in breeding cattle in any herd using ET, AI or simply bull breeding.  Cows with an adequate body condition score will also show much better heats, making AI programs and embryo transfer much easier and more successful.  Skinny cows will not breed and will be a money pit throughout the years as they will be late bred or open.  Take these for what they are worth, but they have really helped us in our herd and I hope they can help others out there get more cows bred to the matings they want!

Thank you dns for the comments.
What your experience with fat cows, donors and receptors?
Also thick control, any experience with what better chemical product (amitraz, fluazuron...etc)?
Thank you.