Maximize pregnancy rates when using artificial insemination
April 24, 2015
Managing factors that producers can influence is imperative when maximizing pregnancy rates.
Artificial insemination (AI) offers cattle producers the opportunity to use semen from high-accuracy, genetically superior sires at a fraction of the cost of purchasing a herd bull with similar genetics.
"In addition, using estrus synchronization and AI can increase the number of calves born earlier in the calving season and increase weaning weights of calves," North Dakota State University Extension Service beef cattle specialist Carl Dahlen says.
A large portion of the economic advantages of implementing AI comes from the number of calves born in a herd from AI sires. The benefits are twofold: an immediate increase in sale value and the long-term benefits of infusing superior genetics into a herd.
As producers prepare for the upcoming breeding season, they can take several steps now to maximize AI pregnancy rates this spring:
-Evaluate the plane of nutrition – Cow body condition score (BCS) serves as an indicator of overall nutritional status. Ideally, cows should 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.
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-Check your records – Calving records can tell you 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 still may be able to get a portion of these females pregnant, but expect lower overall pregnancy rates with AI if they are included in your breeding group.
-Assign reproductive tract scores to heifers – In groups of heifers that have an unknown history, were bought from multiple sources and comingled, or 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, RTS scores can be used to eliminate heifers with poor breeding potential and identify any freemartins, or pregnant, heifers. For optimal fertility with AI 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 can 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 AI dramatically.
-Identify high-fertility bulls – Fertility differences exist among AI 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 AI scenario you plan to implement (fixed-time AI, 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 and 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 performing heat detection 30 minutes per day morning and evening likely will result in missed heats, so consider more frequent and longer heat detection periods.
-Strive for complete compliance with synchronization protocols – Successful synchronization requires each task at each working event be completed. Impacts of noncompliance (missed cattle, improper injections, CIDRs left in, etc.) are accumulative. 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 (.90 x .90 x .90 = 72.9 percent).
-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 AI guns and insemination all need to be done correctly. Producers need to be proficient in AI or should consider hiring an AI technician.
-Work with the weather – Although we cannot control it, we need to understand the impacts that 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) is when the cattle's body temperature is the coolest. If cattle working is required during peak periods of sunlight and heat, provide shade and water when possible, and ample space for cattle to spread out in staging areas. Also ensure cattle spend as little time as possible in closely confined portions of working facilities. In all cases, protect semen and other equipment from the damaging effects of sunlight, wind and precipitation.
-Plan post-AI movement and nutrition carefully – Whenever possible, transport cattle from day one to four after AI or delay the shipment until 45 days after AI to avoid transport-induced pregnancy losses. For drylot-developed females, adapt to summer grass for a period prior to breeding or consider supplementing on pasture to reduce losses associated with rapid diet and environmental changes.
"Many factors can contribute to the success of an AI breeding program," Dahlen says. "Concentrating on managing factors that you can influence is imperative to maximize pregnancy rates and the number of AI calves born in an operation."