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Understanding Expected Progeny Differences for Genetic Improvement in Commercial Beef Herds - AS1770

The beef seedstock business is large, and commercial beef producers have many opportunities to purchase bulls that meet the criteria established in their breeding plans. Breed selection and type vary considerably, and this diversity helps keep a strong genetic base in the beef business. Current bull buyer selection tools include visual traits evaluated by the buyer, as well as performance and genetic information.
Carl Dahlen, NDSU Beef Cattle Specialist
Rick Schmidt,Extension Agent, Oliver County
Lauren Hulsman Hanna,Assistant Professor,Animal Sciences Department
Kris Ringwall,Dickinson Research Extension Center Director


8 Pages

Available in Print

Many of our publications are available in print from the NDSU Distribution Center for a minimum charge of $2.50 to cover shipping and handling. However, many of these publications are free from county Extension offices. Call (701) 231-7882 or e-mail for information on availability, cost and ordering.


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Expected Progeny Differences for Profitability and Efficiency

NDSU Extension Agents encourage the use of Expected Progeny Differences (EPDs) to maximize profitability and efficiency.

Cattle saleA picture is worth a thousand words, unless those words ring false. Many times we find ourselves drawn to pictures, only skimming the text to follow. Most times this is not a problem, however, when it comes to the purchasing of bulls, it is always beneficial to look beyond the picture.

The cattle industry continues to change on a daily basis, tools and resources seem to abound and it can be difficult to sort through the piles of information that present themselves. For the past 30 years, Expected Progeny Differences (EPDs) have been a staple tool within the cattle industry. Unfortunately, many producers shy away from using this scientific tool.

Extension Agent Craig Askim acknowledges that producers understand that pounds mean dollars. “What producers miss sometimes is that while a 500 lbs weaning may be the best they have had in years, using EPDs could potentially get them to 700 lbs. EPDs will help producers see beyond their current situation and into their genetic potential.”

EPDs can be quite intimidating and confusing for even the advanced producer. EPDs reflect numbers that potentially predict the genetic quality of the offspring from that particular bull. However, when producers are able to fully understand the components of an EPD, they will be surprised at their usefulness in helping narrow the field when selecting the next herd sire for their operation.Cattle

Expected Progeny Differences consist of a set of prediction numbers that are based on the averages of that particular breed. Information such as Birth Weight (BW), Weaning Weight (WW) and Calving Ease (CE) can all be found on a bull’s EPD. Each bred has their own predetermined set of averages that are only comparable to other bulls of that breed. It is important to understand the base averages of each breed before comparing bulls of different breeds.

NDSU’s Extension Service Livestock Management Team is currently working on the creation and organization of an EPD Awareness and Evaluation program that will educate producers on the importance of EPDs and more importantly the correct usage of EPDs and how they can increase your profitability and sustainability in your herd. “Using EPDs are a great way to help outline yours goals and objectives.” states NDSU Extension Agent Cole Rupprecht of Cass County.

A local producer recently stated that “I have pretty much had it with articles that say how important EPDs are. If we don’t know how to use them and what they actually represent, there is no use knowing how important they would be for my operation.”

Agents working on the program have the understanding that it will take practice to perfect the ability to correctly use an EPD. The program will strive to provide situations and hands on activity for producers to increase their skill. The goal will be for producers to leave with a deeper understand of the generic merit of their own herd, along with the recognition of their genetic potential.

To fully understand what Expected Progeny Differences can do for you take a minute contact your local Extension Office. Agents will be able to help you evaluate your herd on an individual basis and further your knowledge of EPDs and the role using them will play in your herd’s genetic potential.

NDSU Extension Livestock Genetics Team
Craig Askim, (701) 873-5195
Samantha Lahman, (701) 265-8411

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The First 21 Days of Calving Season

A review of the advantages for calves born in the first 21 days of the calving season.

Several studies have quantified the different advantages that calves born during the first 21 days of the calving season have over those that are born later. Each day a calf is on the ground, it has the opportunity to gain weight, and the relationship between birth date and actual weaning weight is obvious: Older calves are typically heavier at weaning compared with younger calves. However, these effects extend well beyond the time of weaning.

Cow and Feeding CalfIn calves placed in feedlots, the greater feedlot entry weights (a function of greater weaning weights) are followed by heavier final carcass weights, improvements in carcass quality grade and the proportion of carcasses qualifying for premium beef programs for calves born during the first 21 days of the calving season compared with those born later. In addition, a greater proportion of replacement heifers born during the first 21 days of the calving season were cycling at the start of their first breeding season, and this subsequently led to greater overall pregnancy rates compared with heifers born later in the calving season.

We also begin to see impacts of early calving on the cows themselves. The pattern of late-calving cows becoming perpetually late calving and subsequently not becoming pregnant is familiar to all of us. Early calving cows are more likely to become pregnant early in the next breeding season and a recent report (Kill et al., 2012) began to quantify the impacts of replacement heifers calving within the first 21 days of the calving season on longevity in the cow herd.

The average time early calving heifers remained in the herd was 5.1 years compared with only 3.9 years for heifers that calves after the first 21 days of the calving season in 2012a group of 2,195 South Dakota producer-owned cattle. In a group of 16,549 cattle managed at the U.S. Department of Agriculture’s Meat Animal Research Center, heifers calving in the first 21 days, second 21 days and later had an average longevity of 8.2, 7.6 and 7.2 years, respectively. In both cases, data were confined to cattle culled for nonpregnancy, and other types of culls (conformation, temperament, etc.) were removed for the analysis. Taken together, this work showed that early calving heifers had at least a one-calf lifetime advantage compared with late-calving heifers.

This one-calf lifetime advantage also was complemented by extra weaning weight at the end of the breeding season that accumulated to the weight of an additional calf during the lifetime of the cow. Thus heifers that calved during the first 21 days of the calving season had the equivalent of a two-calf lifetime advantage over those heifers that calved after the first 21 days of the calving season. The moral of this story should be to focus on keeping heifers that become pregnant during the first 21 days of the breeding season.

With this in mind, producers may want to consider their heifer development and management strategies and related costs a few different ways. We are all very cognizant of the costs associated with developing heifers through their first breeding season. Producers may not wish to retain any more heifers on breeding pastures than they wish to keep for themselves to control costs.

However, an alternative method of stocking replacement heifer breeding pastures would be to stock enough heifers so that the number of replacements needed would be met solely by those heifers becoming pregnant during the first 21 days of the breeding season. To achieve this stocking rate, the number of heifers on breeding pastures would need to increase according to the proportion we anticipate becoming pregnant early. Data from the North Dakota Beef Cattle Improvement Association’s Cow Herd Appraisal and Performance Software (CHAPS) revealed that the proportion of females becoming pregnant during the first 21 days of the breeding season ranged from 58 to 64 percent during the past 10 years. Therefore, we would conservatively estimate that 60 percent of the heifers would become pregnant during the first 21 days.

To calculate the stocking rates of breeding pastures in this scenario, we would divide the number of replacements we are targeting to retain by 60 percent (0.60). For example, if a producer wishes to retain and calve out 50 replacement heifers, 84 heifers would be stocked onto breeding pastures (50 ÷ 0.60 = 84 total heifers). The divisor used is herd-specific, and producers knowing the proportion of heifers becoming pregnant early in their herds should anticipate accordingly. Perhaps the benchmark of 65 percent of the cows becoming pregnant within the first 21 days is achieved regularly and only 77 heifers would need to be kept.

The number of heifers mentioned above is obviously a much larger number of heifers than normally would be run on many operations. Several items are critical to the success of developing a successful system of retaining only those females pregnant within the first 21 days of the breeding season:

  • Enough high-quality heifers and bull power to stock breeding pastures at suggested rates - If sufficient numbers of high-quality replacements are not available but a second-tier group of heifers is available, then producers are faced with another question: What is better for the long-term profitability of the herd - a better-quality heifer that likely will not last in the herd, or a slightly lower-quality heifer that likely will last in the herd? This can be answered only by the herd manager.
  • Enough winter feed supply and grazing pasture, or money to secure each, to develop extra heifers - Aside from that exception of producers who normally retain nonreplacement heifers as yearling stocker cattle, grazing plans and stored feed supplies would need to be adjusted to facilitate the greater number of breeding heifers maintained.
  • A method of identifying heifers that are pregnant within the first 21 days of the breeding season - Accuracy and timing of pregnancy diagnosis are critical when building a system that relies on knowing when conception occurred. The earlier pregnancy determination can be conducted relative to breeding, the more accurate it will be. In addition, the timing of pregnancy determination is critical to ensure that all pregnant heifers are detected and appropriately classified into groups according to estimated conception dates (for more details, see the August 2011 article in The Ranch Hand titled “Consider Early Pregnancy Checking”).
  • A solid marketing plan for nonpregnant heifers and for heifers that became pregnant after the 21-day breeding target - Remember that we started with a high-quality group of replacements, and because of the diversity in the beef industry, the heifers that became pregnant outside of one producer’s target may be exactly what another producer is looking for. If natural-service bulls are used, then a market for a group of bred heifers needs to be secured. Additionally, a favorable market for nonpregnant heifers should be identified. Quite likely, the open-heifer markets will be complemented by the timing of pregnancy determination (see previous item) because nonpregnant heifers identified early could be sold as grass calves in the late-summer yearling markets.

An additional production system utilized by some beef operations is to breed each heifer a single time via artificial insemination and not run any cleanup bulls. Pregnant heifers are kept and open heifers are sold as stockers at the end of summer or retained through the feedlot phase. In either case, both systems identify the heifers that become pregnant early in the breeding season, and both systems take advantage of the additional longevity and accumulated weaning weight that accompany these early calving heifers.

Given the lifelong benefits of heifers calving early in the calving season, producers may want to implement a system that focuses on retaining only these heifers. Before making this decision, several items need to be considered and a thorough plan developed. In addition, producers should evaluate nutrition and management decisions that offer heifers the greatest likelihood of early pregnancy.

However a question remains: Is early calving per se what leads to the benefits highlighted in the above paragraphs or is it something inherent in heifers that naturally calve early that drives the observed advantages? Whether heifers that become pregnant early only as a result of additional management experience the same benefits of longevity and calf performance as those heifers that become pregnant early without intervention is unknown at this time. Either way, I hope that you have a high proportion of heifers calving within the first 21 days of the calving season that go on to wean large, healthy calves and continue to stay in the herd for many years to come!

Carl Dahlen, NDSU Extension Beef Cattle Specialist

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What Does the Future Hold? Cattle Breeding Techniques

New breeding techniques continue to progess. Here is a review of the latest techniques and those that may be coming.

As we make progress in the field of animal breeding and selection, many “new” technologies surface. Visual appraisal was complemented with performance records, expected progeny differences, ultrasound evaluation of carcass traits and, in recent times, genetic marker evaluation of economically important traits.

While no single method along the continuum seems very far from the next, when one extreme is compared with the other, the progression of tools is quite remarkable. But what else does the future have in store for our industry?

Several researchers have evaluated a process called male germ cell transplantation. The concept of their work is that transferring cells (specifically spermatogonial stem cells) from the testis of a donor male into the testis of a recipient male could result in the recipient producing the donor male’s sperm. The donor sperm would continue to reproduce in the recipient male, and subsequent breeding of the recipient male to a female would result in calves that are the son or daughter of the donor male.

White Calf with DandelionsThe steps of the technique include isolating the spermatogonial stem cells from the donor animal, preparing the recipient animal, using ultrasound guidance to transfer donor cells into the testicles of the recipient, allowing the donor cells to  proliferate in the recipient, and then mating the recipient to females to produce offspring from the donor.

This technique has been proven on a research level but has experienced several issues:

  • Immature bulls have greater concentrations of spermatogonial stem cells compared with mature bulls. This highlights a potential limitation to using mature bulls that are of high accuracy as donors.
  • If high-accuracy sires are to be utilized, the harvest of testicular tissue may harm their own reproductive abilities. In this instance,stem cells would be collected and the donor bull may not be capable of producing additional semen. This would be a short-term issue because the goal would be to develop a perpetual semen supply via recipient bulls.
  • Recipient bulls either need to be immature or go through chemotherapy to eliminate their own spermatogonial stem cells.Once transferred, semen from both the donor and the recipient will be produced in the recipient. In sheep and goats, only 7 to 10 percent of offspring from recipient male breedings are from the donor male.

These issues and others certainly would need to be overcome for the technique to have large-scale applicability. However, if the technique is optimized and available commercially, the face of cattle breeding could change dramatically:

  • Decisions about the type of breeding system implemented would include a cost/benefit analysis among natural service bulls, artificial insemination and recipient bulls producing semen from genetically superior donors.
  • Production systems that do not allow gathering of cattle for artificial insemination (limitations in facilities, labor or simply a function of expansive grazing) would be able to have the highest-quality genetics available via recipient bulls.
  • Climates that are inhospitable to the point where bos taurus bulls could not survive would be able to raise crossbred calves by using bos indicus recipient bulls carrying bos taurus semen.

Whether the process ever will become mainstream is something we can’t  necessarily predict. Transferring embryos from genetically superior donor cows to recipient females is certainly something that was accepted in the cattle industry. However, cost of technology often limits its use. In addition, the term “stem cell” brings in controversy that may make cattlemen shy away from using recipient bulls.

Regardless of the actual future application of the process, just remember this picture: recipient herd sires on your operation carrying semen from virtually any bull in the world. Only the future will tell what happens with our industry, but until then, it doesn’t hurt to imagine the possibilities.

For more detail, see:
Honoramooz and Yang. 2011. Recent advances in application of male
germ cell transplantation in farm animals. Ver. Med. International. Article
Hill and Dobrinski. 2006. Male germ cell transplantation in livestock
Reprod. Fertil. and Devel. 18: 13-18.

- Carl Dahlen, NDSU Extension Beef Cattle Specialist

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Estrus Synchronization for Natural-service Breeding in Beef Cattle - AS1712

Estrus Synchronization
Estrus Synchronization
Breeding systems that utilize natural-service bulls to breed estrus-synchronized females may offer opportunities to get females pregnant earlier in the breeding season, have calves born earlier in the calving season and possibly increase weaning weight of calves born to synchronized females.

Carl R. Dahlen, NDSU Extension Beef Cattle Specialist

4 Pages

Available in Print

Many of our publications are available in print from the NDSU Distribution Center for a minimum charge of $2.50 to cover shipping and handling. However, many of these publications are free from county Extension offices. Call (701) 231-7882 or e-mail for information on availability, cost and ordering.

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Schedule Bull Breeding Soundness Exams Prior to Turnout

Carl Dahlen, NDSU Extension Beef Cattle Specialist

Not all bulls are able to breed cows successfully, and not all bulls that breed cows have semen that can result in successful fertilization and pregnancy. If a bull can’t fertilize cows and you turn him out to breed, you likely will have a lot of nonpregnant cows at the end of the year. 

Breeding soundness exams can uncover potential problems with young bulls that were just purchased and older bulls that already have sired calf crops. However, less than 20 percent of U.S. producers perform breeding soundness exams on their bulls prior to spring turnout. 

Breeding soundness exams include examination of the bulls’ physical structure, reproductive organs and semen.

Physical Structure

The physical examination is important because bulls with proper structure are more likely to hold up under the rigors of the breeding season than bulls with structural problems. Structural problems of the feet and legs or movement in general are a big issue because bulls are asked to cover a lot of ground and need to be free of physical problems to breed cows successfully.

Bulls will lose body condition during a breeding season, so they must enter the season with adequate condition.

Seeing the mounting behavior of cows in heat helps the bull identify who is ready to breed from across the pasture so bulls must have good vision.

Reproductive Organs

The penis, testicles, prostate and other reproductive organs are evaluated to make sure they are free of injuries or defects that would prohibit a bull to breed cows successfully.

Scrotal circumference is heavily scrutinized in young bulls because it is an indicator of semen volume. As young bulls grow, the standards for adequate scrotal circumference also increase. For example, a bull that is less than 15 months old should have a circumference of at least 30 centimeters (cm), whereas a bull more than 24 months old should have a scrotal circumference of at least 34 cm.

Bulls with an inadequate scrotal circumference often are taken out of production sales or sold at discounted rates, with their inadequate scrotal circumference mentioned at sale time.


A sample of semen is evaluated for motility, morphology and concentration.

Motility is the movement of sperm, and, ideally, a sample will have a rapid swirling movement. If sperm are not moving in a synchronized manner (think synchronized swimming), they may not be able to swim successfully through the female reproductive tract to the site of fertilization.

Morphology is an evaluation of the structure of the sperm. Ideally, the sperm will have heads and tails of proper shape. A high proportion of sperm that has incorrect structure will not result in successful fertilization.

Just because a bull sired calves last year does not mean he can do it again this year. Injuries during the nonbreeding months, as well as effects of extreme cold weather and frostbite, can render once-fertile bulls infertile. The process of making sperm, spermatogenesis, takes 60 days, so frostbite or other injuries that occur in March may be lingering in May.

Perform breeding soundness exams close to the time of breeding to ensure recovery from winter injuries but enough time in advance of turnout to find new bulls if the exam finds fertility problems.

Considerations beyond a breeding soundness exam

  • Stocking rate (number of cows a bull is required to breed): The nationwide average stocking rate is 25 cows per mature bull or 15 cows per yearling bull. Stocking rates of up to 50 cows per bull are used in some systems, but high stocking rates may lead to cows not becoming pregnant on their first heat of the breeding season and subsequently calving late the following year.
  • Libido (willingness to breed): Can be determined only when bulls are on pastures or in pens with females in heat. Bulls may have all of the qualifications to pass the breeding soundness exam, but if they aren’t actively breeding cows, producers must find a different option.

Watch breeding activity closely because catching and correcting problems during the breeding season is much more profitable than waiting for open cows to calve.

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Cold Exposure and Bull Fertility

Revised January 2009

PDF version

Gregory Lardy, NDSU Animal & Range Science

The extreme combination of cold temperatures and blizzard conditions during winter months is always a concern to cow-calf producers because of the added difficulty in feeding and caring for the cattle herd. First priority for most cattle producers is the well-being of the cow herd. Herdbulls, which are generally kept separate from the cowherd, may experience equal hardship if proper nutrition and shelter are neglected. The future reproductive success of the herd will suffer if herdbulls are not prepared for or protected from winter weather. Like the cowherd, herdbulls need to be maintained in a body condition score of 5 to 6 in order to be in ideal breeding condition. Low temperatures and windy conditions can easily increase feed requirements 25 to 30 percent above normal maintenance requirements. Also, lack of wind protection and lack of bedding will increase the chance of frost damage to the scrotum and testicles. During normal winter conditions frostbite is not a common problem with breeding bulls, but prolonged exposure to extreme cold and wind increases the incidence of frostbite and is a problem that must be considered when planning for the breeding season.

Evidence of frostbite to the scrotum is usually apparent a few days after freezing in the form of noticeable inflammation and swelling. The heat generated from the inflammation directly affects the sperm that are maturing and stored in the epididymis, which surrounds the testicle at the lower end of the scrotum. The resulting damage may cause temporary or, in more severe cases, permanent sterility in the bull. A scab may appear on the lower portion of the scrotum as healing occurs. However, the absence of a scab does not indicate that frostbite injury has not occurred. Severe frost damage to the testicle and epididymis may cause tissue adhesions, affecting mobility and circulation within the scrotum.

Evaluation of possible frostbite damage is best accomplished by a trained veterinarian performing a breeding soundness examination 45 to 60 days after the injury occurred. A semen evaluation performed earlier than this period will most likely indicate poor semen quality and could result in unnecessarily culling a bull that may produce satisfactory semen after healing has occurred. An examination normally includes a physical evaluation of the entire reproductive tract including the testicles and epididymis, as well as a microscopic semen evaluation recording sperm motility and morphology. The following table illustrates the importance of having a breeding soundness exam completed before the breeding season.

Effect of severity of frostbite on semen quality in bulls


Severity of Frostbite

Soundness Score




Satisfactory (%)




Questionable (%)




Unsatisfactory (%)




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