Benchmarks for The Evaluation of Single Fixed-Time Artificial Insemination

By Charlie Francisco


Editor’s note: Sometimes a “good idea” takes time to fine-tune and get right. Single fixed-time artificial insemination (AI) is not new to animal agriculture. Animal health companies began to design pharmaceuticals to facilitate timed artificial insemination for the dairy industry over 40 years ago. Successful fixed-timed AI is accomplished through the strategic use of gonadotropins, prostaglandin, progestagens (CIDR), or GnRH. Using these pharmaceuticals, dairy cows are artificially inseminated using fixed-time AI protocols without regard to behavioral estrus. These products have been applied to the beef industry, which has expanded across the USA.
In 2013, JBS United Animal Health successfully launched OvuGel®, a FDA licensed gel formulation containing a GnRH-analogue. OvuGel® is the first product approved for synchronizing ovulation followed by a single fixed-time AI in weaned sows. We asked one of JBS’ experts how and why this technology could impact the industry. Fertility results from OvuGel®-treated sows are equivalent to those of untreated sows inseminated on each day in standing estrus 1-4.


When using single fixed-time AI, all sows within a single weaning group are treated the same. All subsequent matings are synchronized from the weaning date and time. In order to obtain optimum results after treatment, daily boar exposure and proper feed intake must not be restricted. The treatment is administered intravaginally to healthy sows 96 hours after weaning. Twenty-four hours later, all sows are inseminated with a single dose of semen without regard to estrus. Thus, there is no need for heat detection, which effectively decreases labor costs and increases throughput and utilization of inventory.


Gestation length within a group of sows after single fixed-time AI is less variable than after AI on each day sows are in estrus. All sows treated on the same day will ovulate 40-48 hours later. This breeding precision facilitates a synchronized farrowing for the majority of the breeding group, which provides an opportunity for careful attention to day one pig care and reduction in stillborn rates. An even tighter synchronized farrowing may be achieved by induction of parturition with prostaglandin F2 alpha.


In conventional breeding programs, only weaned sows exhibiting standing estrus are inseminated. Return to estrus post-weaning varies depending on health, season, and genetics. Usually, the percentage of sows that are actually mated within seven days after weaning cannot be accurately identified from records. Often, cull sows may or may not be included within the measure; therefore not all sows that are breeding eligible are identified.

The metric or benchmark to evaluate 30-day conception rate and farrowing rate for herds using OvuGel® and single fixed-time AI must be re-evaluated. The traditional breeding program ignores the sows that do not come into estrus within seven days after weaning, whereas the single fixed-time AI breeding program accounts for them in its calculation. For example, a group of farms may have very similar 30 day conception rates of 95%. However, this same group of farms may vary greatly in the number of weaned sows bred within seven days after weaning; perhaps from 80% to 95%. Farrowing rate of sows bred within seven days after weaning may range from 76% to 90%. Note that the traditional 30 day pregnancy rate was the same. Hence, although one may have a very high pregnancy rate or farrowing rate based on present day conventional calculations, there could be a significant number of open sows remaining in the weaning group.

This example illustrates a remarkable difference in farm efficiency and likely profitability and questions the value of traditional 30-day conception rates. What is the conventional conception rate measuring? Simply, “The ability of an AI technician to produce pregnancy in a reasonable proportion of sows which have been determined to be in estrus.” It may also be an indicator of semen quality. Clearly, conception rate is an indicator of the AI technician’s ability to find sows in heat and how skilled he/she is in breeding sows he/she finds in estrus. Conventional conception rate does not indicate the quality of the sow that was weaned, and therefore, nothing about the efficacy of subsequent farrowing protocols.

“Conventional conception rate does not indicate the quality of the sow that was weaned, and therefore, nothing about the efficacy of subsequent farrowing protocols.”

An alternative approach is implementation of the single fixed-time AI breeding program. As stated above, this breeding program uses the total number of weaned sows (minus culls) on Day 0 as a starting point and, as such, is the denominator in the calculation for conception and farrowing rate. This concept differs greatly from the traditional breeding program where the number of sows bred by Day 7 after weaning is the denominator. Sows that have not expressed estrus by Day 7 after weaning are ignored when considering the efficiency of sow herd utilization in the traditional breeding program. As described above, traditional conception and farrowing rates can be very misleading, (76% vs. 90%) when using this measure to assess sow utilization. By accounting for all breeding eligible weaned sows less the number of culls for the calculation, the industry would be more accurate in evaluating sow herd utilization and production efficiency. The challenge remains to find metrics that truly measure breeding technique and semen handling/quality.

Impact of single fixed-time ai on utilization rate reproductive performance on three commercial farms

For controlled or side-by-side trials, the number of allotted sows for each group is known. Both a conventional conception rate (no. pregnant/no. served) and a weaned sow conception rate can be calculated (no. pregnant/no. sows in wean group). The comparison of these benchmarks is shown in Table 1. Regrettably, in herds evaluating the performance of single fixed-time AI by using computer-generated production reports, only the conception rate is available. The number of sows not in estrus and thus not served [9 (100-91=9)] in table, cannot easily be determined from production records because voluntary culled sows are typically not accounted for. The number of sows bred within 7 days after weaning is the starting point and, as such, is the denominator in calculating conception rate and farrowing rate.

When using the single fixed-time AI program, all sows that are weaned and retained are eligible for mating. One hundred treated sows were retained for breeding and all were subjected to a single fixed-time AI. Conversely, 100 control sows were retained for breeding, but only 91 were subjected to the conventional breeding program. Note that the control sow farrowing rate was higher than the treated sow farrowing rate when based on number of sows inseminated that were in heat by 7 days after weaning (87.9% vs 83.0%). Whereas the control weaned sow farrowing rate was lower than the treated weaned sow farrowing rate when based on the total number of breeding eligible sows (80.0% vs. 83.0%).

Using single fixed-time AI, fertility is unchanged, resulting in the same number of pregnant sows or more. However, when using single fixed-time AI, some sows conceive that normally would not have been bred. They were mated regardless of estrus expression and these three extra sows (83 single fixed-time AI sows farrowed vs. 80 Control sows farrowed) would have been missed using traditional methods. Efficiency is calculated by using the number of animals in a breeding group, instead of using the number of animals that were inseminated by 7 days after weaning. This example demonstrates the effect of the fixed-time AI program on long-range improvement in breeding inventory utilization

“for every 100 weaned sows, approximately 3-4 more sows were pregnant using single fixed-time AI”

Weaned Sow Utilization (WSU) measures how efficiently a farm is getting weaned sows bred or farrowed. WSU is the percentage of weaned sows moved to breeding, which were bred within seven days and conceived. Pregnancy utilization is calculated by: % Mated by seven days after weaning x % Pregnant. Whereas, farrowing utilization is:
% Mated by seven days after weaning x % Pregnant x % Farrowed.

Unlike the conventional performance parameters, Conception and Farrowing Rates, WSU accounts for the total number of sows that were moved to the breeding barn at weaning with intention to rebreed. Again, a farm can have a high conception rate, but the WSU could be low if they are getting a low number of sows bred back within seven days after weaning. WSU not only measures the breeding team’s AI skills, it also takes into account how many sows return to estrus within seven days after weaning. This shows a more complete picture of the reproductive health of a farm.

impact of single fixed time ai on weaned sow utilization

Table 2 illustrates three farms that have converted all weaned sows to single fixed-time AI. The overall WSU improved by 3.5 percentage points. So, for every 100 weaned sows, approximately 3-4 more sows were pregnant using single fixed-time AI. Using an Excel worksheet, weekly weaned groups can be recorded and entered to calculate the WSU. This can be done to audit and troubleshoot or one may continually monitor for breeding performance efficiency.


Just as AI impacted genetic improvement, single fixed-time AI has significant implications to sustainable genetic improvement. Pigs per semen dose will be significantly greater after single-fixed time AI than after conventional AI on each day of estrus, thus contributing to continuous quality improvement. Similarly, by improving the accuracy of benchmarking metrics, the industry can further understand the role of genetic improvement within the sow population by using a more accurate measurement of sow utilization.

The long-range goals of single fixed-time AI are the same as conventional AI. Transition to conventional AI began over 25 years ago. Today, the impact on genetic improvement, inventory utilization, reduced piglet variation and greater labor savings can be substantially improved with single fixed-time AI. The benefits can be found for both breed-to-wean and wean-to-finish production. However, the metrics for evaluating breeding herd performance must be reconsidered and perhaps modified to accurately assess farm efficiency.

REFERENCES 1. Knox, R. V., S. M. Breen, J. Taibl, M. E. Swanson, and S. K. Webel. 2012. Determination of optimal dose and time of administration of intravaginal triptorelin gel for synchronizing ovulation in weaned sows. 2012 ADSAAMPA- ASAS-CSAS-WSASAS Joint Annual Meeting, 7/15/2012-7/19/2012, Phoenix, Arizona. 2. Taibl, J., S. Breen, S. Webel, and R. Knox. 2008. Induction of ovulation using a GnRH agonist for use with fixed time AI in weaned sows. Theriogenol. 70:1400. 3. Augspurger, N. R., M. E. Johnston, M. E. Swanson, and S. K. Webel. 2012. Single and double, fixed-time insemination of postpartum sows given intravaginal triptorelin gel. 2012 ADSA-AMPA-ASASCSAS- WSASAS Joint Annual Meeting, 7/15/2012-7/19/2012, Phoenix, Arizona. 4. Freedom of Information Summary, NADA 141-339. 2012.

Charlie Francisco, DVM, MS has joined JBS United Animal Health, Inc., and will serve as Director of Technical Services. Dr. Francisco has worked as a swine technical service veterinarian for the past 17 years in the veterinary pharmaceutical industry and more recently as Director of Swine Technical Service for Merck Animal Health. His primary focus in swine production medicine is swine breeding management and gilt development. Graduated from University of Illinois in 1989 – DVM, University of Illinois for a Residency in Production Medicine 1993-MS, University of Illinois – EVP 1998. Dr. Francisco is based out of his home office in Mahomet, IL. His contact information is: Charlie.Francisco@JBSUnited.com or (217) 898-5903