Artificial insemination (AI) has been a standard breeding practice in purebred cattle herds for many years. There are also viable reasons to use AI in a commercial herd as well. Some of these reasons include:
- The use of genetics not usually available on a local basis.
- The production of replacement heifers with superior genetics.
- Coupled with estrus synchronization, consolidation of the calving season.
- The need for fewer bulls in the breeding season.
- Higher growth performance and calf value.
- The production of calves for specialty markets such as club calves.
Bull studs have a wide variety of bulls available for AI use. Most breeding and herd improvement objectives can be matched with bulls that are available. This can include traits ranging from weaning weight, milk production, carcass traits, docility, and others. These bulls can also provide outcross or crossbred genetics that may not be available locally.
A major reason to use AI in the commercial herd is the production of replacement heifers. Generally, a within-herd selection program for replacements will be relegated to the progeny of just a few cows in order to make any maternal improvement in the herd. Heifers selected from across the herd will retain little more than average performance. With AI use sires can be selected specifically for maternal traits such as milk production, calving ease, birth weight, docility, and others to provide maternal improvement. The use of EPDs and other selection tools also provides the advantage of simultaneously improving growth, carcass traits, and other factors with careful sire selection.
Crossbreeding programs can utilize AI to capture additional heterosis or in the production of replacement females in a terminal sire program. For example, two breeding herds would normally be needed for a crossbreeding program with a 2-breed crossbred cow (one herd to produce these replacements) and a second herd bred to terminal sires. The use of an AI program could eliminate the herd used to produce replacements. Reciprocally, the use of AI for a terminal sire would replace this breeding herd, while replacements could be generated by live matings. Traits of economic and herd importance could then be more effectively targeted.
Numerous estrus synchronization (ES) protocols are now available. These programs have been refined and provide the potential for being highly successful to reduce the labor of estrus detection and consolidation of AI activity. The reader should review the protocols in general use presented by the Iowa Beef Center website. An advantage for the commercial herd is that the calving season may be more concentrated, reduce observation at calving time, and provide a more uniformly-aged calf crop to assist in weaning and marketing management. The use of AI and ES is not without additional cost. Table 1 provides an outline of possible costs for AI and ES. The costs and returns in the table are based on actual costs incurred in the Pennsylvania Heifer Development program, and the returns are an average from several years of AI and ES programs here in Penn State herds. Recall there is variability in the rate of estrus and the pregnancy rate across farms. Nutrition, health, general management, semen management, and technician proficiency will significantly affect the results of an AI program. In general, the results in Table 1 show it will cost about $100 in many cases to produce an AI calf. Simply from a production standpoint, about 50-60 lbs. of additional weaning weight for steer calves or as little as 10 extra pounds of weaning weight per year for the life of a replacement heifer from the AI sire will cover the cost. Any additional advantages from crossbreeding heterosis, calving ease, or milk production are also captured.
Estrous synchronization itself can also enable you to potentially have higher returns on your investment. Not only is there an performance advantage found in AI sired offspring, but with more calves being older at weaning will also allow for more revenue at marketing (Steichen et al., 2013). This allows you to capture a double benefit of incorporating AI and ES programs in your operation. In addition, calves should be more uniform in weight allowing for marketing advantage. It is well documented (Barham and Troxel, 2007; Alkire et al., 2012; Troxel et al., 2013) that larger groups at auction bring additional premiums. A larger number of older calves that have a performance advantage will have group marketing power.
Timed AI (TAI) is a procedure when synchronization is coupled with breeding with no observation of the cattle for signs of estrus. Cattle are simply run through the chute at the appointed time and bred. The refinement of ES protocols has made this process available. Our experience here with the Pennsylvania Heifer Development program over 2 years was we could consistently achieve 66% pregnancy rates to TAI. Other reports have shown there is the normal variability across farms (40% to 80% pregnancy rates). Provided the ES protocol has been administered correctly, an advantage for TAI is getting some cows and heifers bred than show no signs of estrus from observation.
Any cows or heifers that get bred by AI do not require a bull. Bulls are generally one of cheapest and best investments in a commercial cow herd, but an effective AI program can easily reduce bull needs in half offsetting the investment of AI. For the 30-cow herd, this means even a yearling bull may be all that is needed to clean up breeding.
Sexed semen is now widely available for AI programs. This technology provides a significant advantage for the production of replacement heifers or for the production of club calves. However, sexed semen is more costly, so the expertise and effective administration of AI and ES programs are magnified. In addition, J. B. Hall (2013) reported several studies with use of sexed semen in beef heifers and cows indicated pregnancy rates are 10% to 20% lower with sexed semen compared to conventional semen (Seidel et al, 1999; Seidel et al., 2000; DeJarnette et al., 2009). In general, Hall indicated the major AI studs report 10% to 15% reduction in pregnancy rates to sexed semen compared to conventional semen. The high cost of sorting the semen by sex, the loss of 50% of an ejaculate when sorting, and a significantly lower number of viable sperm in a straw of semen result in higher cost and lower returns.
Effective health and nutritional management will be the keys to any breeding program, and these features will be even more important in an AI and ES program. However, there are several advantages available to the commercial herd for using AI.
Table 1: Example cost associated with Artificial Insemination (AI) and Estrous Synchronization (ES) implementation in beef cattle operations.
|Number AI matings1||Handling Trips||Bull cost2||Semen cost3||Technician cost4||CIDR cost||GnRH Cost||PG cost5||Labor cost6||AI Calves7||Cost/ AI calf|
|Select Synch + CIDR||32||3||0||640||320||420||210||175||204||19||103.63|
|Select Synch + CIDR+TAI||35||3||0||700||350||420||228||175||210||21||99.19|
|6-day PG + CIDR||30||4||0||600||300||420||210||350||270||18||119.44|
|7-day CIDR + PG||32||3||0||640||320||420||0||175||204||19||92.58|
1 Number of AI matings = number of cows exhibiting estrus to synchronization from 35 total cows.
2 Bull cost = cost of bull per cow; $3,500 initial price; used for four years.
3 Semen cost = $20 per unit (cost of semen, shipment and storage); CIDR cost = $12 each; GnRH cost = $6/dose.
4 Technician coat = $10 per AI service.
5 Prostaglandin cost = $5/dose.
6 Labor cost = $2 per cow each time in the chute.
7 AI calves = number of calves born to AI mating; fixed at 60% of AI mating's of the herd.
Prepared by Dr. John Comerford, retired professor. Revised by Ben Williamson.