We have come a long way from the synchronization programs of one shot of prostaglandins, observation, and breeding according to heat.
Prostaglandins are still a very useful tool in combination with other drugs and intravaginal devices containing progesterone. Many of you will have seen the numerous protocols put out for synchronization — American Breeders Service has a very nice summary in one of its catalogues. The only problem with so many choices is it might become confusing and if protocols are changed, or times are not strictly adhered to, disastrous conception rates follow.
In my experience, the best protocol (for a number of reasons) is the CO-Synch plus Intravaginal progesterone-releasing device (CIDRs). The program’s chart is available for download here. If you choose to use the program, get the flow sheets laminated and put up on the fridge or someplace else so it can easily be followed. With this program, there is a slight difference in the time period after the prostaglandin shot — six hours shorter for heifers — so please note that before proceeding.
Keep in mind this program is really good for allowing full synchronization so all cattle are bred at the same time. Some producers do AI a few if they come into heat early but the rest are AIed at once. There is no need for heat detection. Cattle are run through the chute a total of three times including when they are AIed over a 10-day period, so your handling setup must be decent. Good facilities reduce labour and decrease stress on the cattle, which helps improve conception rates.
- From the Canadian Cattlemen website: Improve your herd’s breeding efficiencies
As with handling of any of the medicines, keep them from freezing or getting too hot. Since shots are intramuscular, it’s very important to use at least a 1.5-inch needle and give the injections in the neck where you can get into the muscle. Because the dosages of both the GNRH and prostaglandin are smaller, it is critical to get them all into a site where they will be absorbed quickly. Fertagyl, Fertiline Cystorelin and Factrel are the GNRH products used and efficacy is good on all.
As far as the prostaglandins are concerned, the two oldest ones are lutalyse and estrumate but there are also several generic products licensed. Estrumate is two cc whereas lutalyse is five cc. A very common mistake arises from changing products, but not changing the dosage — with underdosing or overdosing the result. Both mistakes (especially the underdosing) can greatly mess with any synchronization program. So follow the label closely.
We always hear about the high and low pregnancy rates, but a good average on a timed AI program is 50 per cent. The time frames are critical, so don’t synchronize more than you can possibly AI in three hours. Semen must be placed at the ideal time and, of course, follow all the artificial insemination protocols for handling thawing and placing the semen. Keep the area clean and use a good absorbent towel to clean the vulvar area.
As with any breeding program, cattle must be cycling and in good nutrition with an adequate body condition score (2.5 to 3.5), and have a sound mineral program. Cows should be 60 days from calving so their uterus has fully involuted (contracted down) and they are ready to rebreed. Cattle on a rising plane of nutrition (so they are gaining weight) will also have a better conception rate. The demands of a calf sucking milk on the cow needs to be replaced by good-quality feed in the cow’s diet otherwise cycling will not happen.
For heifers you can use a program using MGA (Megesterol Acetate) that keeps the heifers from cycling. This is fed for 14 days and then removed. The heifers come into heat but it is not a fertile heat, so they are given a shot of prostaglandins to complete the synchronization and the heifers are then bred according to detected heat. The majority will be in heat over about a three-day window.
All synchronization programs require a strict adherence to detail and timing. There are many different protocols out there, so work with your veterinarian to determine which ones they have had the best success with. Another good reference will be your semen sales rep as they usually have experience with AI and often work with local veterinarians to implement synchronization programs.
If in doubt about any of the details, ask questions. Ideally it is best if men do the handling of the prostaglandin, as there is a huge safety factor for women because — as the label clearly states — this product should not be handled by women of child-bearing age.
If you implement a synchronization program, you can cut down on bull power and can utilize the best genetics in the industry. It all can work well and a desirable conception rate achieved as long as all the steps are followed in order of sequence and at the proper times. May the conception rate be high this spring!