Content ID

330403

Synchronization streamlines artificial insemination

Choose a plan to time estrus with breeding.

Realizing the potential genetic benefits of artificial insemination (AI) in cattle has historically required a prolonged period of labor-intensive heat detection. However, using hormones to synchronize heat in cattle lets producers sidestep most of the labor and instead breed females on a set schedule.

Protocol Options

Several protocols for synchronizing heat in beef cattle are recommended by the Beef Reproduction Task Force (BRTF), a group of university reproduction specialists. Protocols for cows and heifers differ because of the differences in physiological responses between the two groups.

The protocols vary in cost, animal-handling needs, and heat-detection periods. Most products used for synchronization require a veterinarian’s prescription.

“The cost of the synchronization products ranges from a few dollars to close to $20 a head, depending on the protocol,” says Sandy Johnson, a reproductive physiologist and Extension beef specialist at Kansas State University. “The cost varies with source and quantity purchased.”

For instance, the most basic synchronization protocol for heifers requires a 12-day period of heat detection, with a prostaglandin (PG) injection on day five for those heifers not heat detected and bred in the first five days. Heifers are bred as they come into heat.

In a second protocol, the heat-detecting period is reduced to seven days by adding a controlled intravaginal drug release (CIDR) device, which is inserted into the animal’s vagina. The CIDR releases the hormone progesterone. Removing the insert and injecting PG on day seven initiates estrus for a subsequent seven-day period of heat detecting and AI.

The most cost-effective and oldest AI protocol for heifers involves feeding melengestrol acetate (MGA) for two weeks in the ration; 19 days after the end of the feeding period comes a PG injection. 

“The most common approach with this protocol is to heat-detect for a few days and then inseminate any females not previously observed in heat at 72 to 84 hours after PG,” Johnson says. An injection of gonadotropin-releasing hormone (GnRH) is also administered at breeding.

A potential drawback to the MGA system is the variability that can occur in individual feed intake; some heifers may not consume sufficient amounts. Using a CIDR insert in place of the MGA removes the uncertainty of feed intake.

Synchronization protocols eliminating heat detection and centering instead on fixed-time AI “have a lot of appeal,” Johnson says. “It’s easier to schedule a set time for people to help.”

Three fixed-time AI protocols require the insertion and removal of a CIDR and the administration of one or two injections of PG before breeding, which occurs at a set time after the PG treatment. An injection of GnRH is administered at time of breeding.

“Within the group of recommended synchronization protocols, conception rates are similar and comparable to natural service,” Johnson says. “In large data sets, conception rates resulting from AI are equal to those from natural service.

“Pregnancy rates from any kind of an AI program will be dictated by a number of factors, including, but not limited to, cow condition, your ability to implement the synchronization system correctly, the accuracy in the timing of insemination, and the fertility of the bull that you select,” she adds.

Visit the BRTF website (beefrepro.org) for more information about synchronization protocols. The site also offers an Estrus Synchronization Planner and an AI Cowculator to help you determine the economic feasibility of AI for your herd.

Read more about
Loading...

Talk in Marketing