Take steps to maximize pregnancy rates when using A.I.

Carl Dahlen

A large portion of the economic advantages resulting from implementing A.I. comes from the number of calves born in a herd from A.I. sires. The benefits are twofold: an immediate increase in sale value and long-term benefits of infusing superior genetics into a herd.

As producers are preparing for the upcoming breeding season, there are several steps that can be taken now to maximizing A.I. pregnancy rates this spring:

Evaluate plane of nutrition: Cow body condition score (BCS) serves as an indicator of overall nutritional status. Cows should ideally be at a score of 5 to 6 on a 9-point scale. However, absolute BCS is only part of the story.

Making sure cows are on an increasing plane of nutrition leading up to the breeding season will help maximize pregnancy rates.
Check your records: Calving records can tell us a lot about the likelihood of success when breeding specific females. Identify cows less than 45 days postpartum at breeding and cows that had very difficult births.

You may still be able to get a portion of these females pregnant, but expect lower overall pregnancy rates to A.I. if they are included in your breeding group.
Assign reproductive tract scores to heifers: In groups of heifers whose history is unknown, groups that were commingled and bought from multiple sources or groups that you just haven’t had time to watch closely, consider having a veterinarian assign reproductive tract scores (RTS) to the heifers.

Based on the size of the uterus and ovarian structures present, RTS scores increase can be used to eliminate heifers with poor breeding potential and identify any freemartin heifers. For optimal fertility with A.I. breeding, 50 percent of all heifers should have an RTS of 4 or 5 about 45 days prior to breeding.
Follow pre-breeding vaccine labels: Pre-breeding vaccinations are given to help protect cattle from several types of viruses and bacteria that can cause reproductive failure. Be sure to follow label recommendations when giving pre-breeding vaccines.

Working events in many estrus synchronization protocols coincide with times when vaccine administration would be off-label, and vaccinating at these times could reduce pregnancy rates with A.I. dramatically.
Identify high-fertility bulls: Fertility differences exist among A.I. sires, so be sure to review current estimates of sire fertility published by semen companies or talk with your semen supplier about which bulls consistently have generated superior fertility in the A.I. scenario you plan to implement (fixed-time A.I., heat detection, etc.).
Work cattle calmly: Each person working cattle always should practice calm, low-stress handling techniques through adequate facilities, or stress may lead to poor results.

Moving cattle calmly through facilities several times in advance of the breeding season can reduce the stress of subsequent handling events, improve cattle temperament and may increase pregnancy rates.
Be diligent with heat detection: Producers wishing to use protocols that include heat detection must identify cows that are in heat. Not catching cows that come into heat will lead to disappointing results.

Old thumb rules of 30 minutes per day morning and evening will likely result in missed heats, so consider more frequent and longer heat detection periods.
Strive for complete compliance to synchronization protocols: Each task at each working event is required for successful synchronization, and impacts of noncompliance (missed cattle, improper injections, CIDRs left in, etc.) are additive.

If every task is completed correctly 90 percent of the time, and a protocol requires three working events, the end result would be that 72.9 percent of females were synchronized correctly (0.9 × 0.9 × 0.9 = 72.9 percent). Strive for complete compliance when executing tasks to limit negative additive effects.
Handle semen and inseminate with proper technique: Proper semen handling begins when the semen arrives on the ranch. Transfer semen from dry shippers to storage tanks as soon as possible, and make sure the tanks have plenty of nitrogen and are kept in a safe place. Thawing semen, loading A.I. guns and insemination all need to be done correctly.

Producers wishing to A.I. their cows need to be proficient at A.I. or should consider hiring an A.I. technician.
Work with the weather: Although we cannot control it, we need to understand the impacts weather can have. For summer breeding seasons with heat in the forecast, be sure to schedule working and breeding activities for the coolest period of the day when possible.

Early morning (first light) will be the time of day when the body temperature of cattle is the coolest. If cattle working is required during peak periods of sunlight and heat, provide shade and water when possible, provide ample space for cattle to spread out in staging areas, and ensure cattle spend as little time as possible in closely confined portions of working facilities.
Plan post-A.I. movement and nutrition carefully: Whenever possible, transport cattle from day one to four after A.I. or delay shipment until 45 days after A.I. to avoid transport-induced pregnancy losses.

For drylot-developed females, either adapt to summer grass for a period prior to breeding or consider supplementing on pasture to reduce losses associated with rapid diet and environment changes.

Many factors can contribute to the success of an A.I. breeding program. Concentrating on managing factors we can influence is imperative to maximize pregnancy rates and the number of A.I. calves born in an operation.

Best of luck this breeding season.