When deciding what synchronization program to use in your herd, several factors must be considered.
Do you have the time to detect an animal in heat, or do you want timed breeding?
Cost is a consideration, because timed artificial insemination programs require more financial commitment and more passes through the chute.
There are three synchronization programs that I find the most successful. There are numerous options available and your veterinarian or semen sales representative may have recommendations. Also, talk to neighbours to see which programs have worked for them.
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The keys are to avoid complicated systems and write the protocol down so nothing is left to chance. Success depends on details.
With any synchronization program, cows and heifers must be in good health and have a sound nutritional program. All the factors that lead to a high conception rate with natural breeding are the same ones that must be incorporated into a synchronization program. Synchronization is not a substitute for poor management.
Heifers must be at the two-thirds mature weight to breed. Adequate energy and trace minerals must be in the ration. A good body condition score of 2.5-3.5 is necessary. The cattle should be vaccinated for reproductive diseases in the area such as BVD and IBR. Recently calved cows should be gaining weight on a rising level of nutrition and be at least 60 days postpartum. If the semen is of high quality, the only thing left is to fine tune the synchronization programs.
If labour is not an issue and the skill level for heat detection is high, the original program of two shots of prostaglandin is still effective.
The two shots are given 10 days apart and cattle are observed closely for heats in the two to five days after the second shot, then bred accordingly.
Be careful because the two commonly used prostaglandins on the market have different dosages. Lutalyse, the natural one, is five cc and estrumate, the synthetic one, is a two cc dosage.
Always give these products with a long needle because this low dosage product must go deep into the muscle. Use the neck muscles preferably for all these injected products.
The producer can also observe and breed off heats picked up after the first shot of prostaglandin.
If the cows cycled well before, about 70 percent of them will cycle in the first several days after the first shot. Those that aren’t bred after the 10 days are given the second shot. This cuts cost but increases labour because you are breeding over a longer time.
An excellent program but only for heifers is the MGA (megesterol acetate) program. MGA is a progesterone compound primarily used in feedlots to keep heifers from cycling. Heifers are fed 0.5 mg/hd/day for 14 days. Most feed mills will have this mixed in a small amount of grain or in pellet form, making it easy to administer the proper amount. This is fed for 14 days exactly, then stopped. With the progesterone source removed, almost all the heifers will come into heat in two to six days.
A big word of caution here is that this is not a fertile heat. We then go in with a prostaglandin shot (remember the dosage difference) 17 days after the removal of the MGA. The heifers will be in standing heat two to five days after the injection and are bred accordingly. This program does not work on cows even when a higher dosage of MGA is used, so do not under any circumstances use this program on cows. The results are too inconsistent.
The last program involves the use of CIDRs and fixed timed AI, where all cattle on the program are bred at a specific time. The advantage is more efficient use of labour and management. If the producer hires a technician, the whole group gets AI together.
The CIDR is a vaginal implant, which releases a controlled amount of progesterone daily. There are probably 15 different programs using CIDR in the industry today.
All three programs have merit so discuss them with a veterinarian. The goal is to get as high a conception rate as possible in a short time. Conception rates with all these programs depend on attention to detail but should be close to those achieved by breeding off natural heats.
Roy Lewis is a veterinarian practising in Westlock, Alta.
