Crossbreeding is a favorite topic for beef producers. In fact, any discussion of breeds always leads to the question of whether one breed can “do it all.” Beef cattle research results are numerous with respect to crossbreeding benefits, breed combinations, breeding systems and heterosis values. Popularity of Angus cattle is readily apparent in today’s beef production, from cow herd performance to branded beef products. Even with the traditional research addressing crossbreeding and its benefits, an emphasis toward straightbred and high-percentage Angus breeding is increasing in commercial herds. The following summary contains reference to crossbreeding concepts, and it poses questions faced by cattle breeders with respect to the role of today’s Angus in cattle systems of the future.

What is crossbreeding?
Crossbreeding is the mating of individuals of different breed makeup. Improvements in efficiency can be dramatic if appropriate choices are made. Crossbreeding does not eliminate the need for superior purebred cattle since an efficient crossing system uses well-characterized, outstanding seedstock resources. Crossbreeding is one type of a larger class of mating systems called outbreeding. Outbreeding has the opposite effect of inbreeding and is defined as the mating of relatively unrelated individuals. Other forms of outbreeding include:
• Linecrossing — the mating of members of different families within a breed;
• Grading-up — mating the sires of a given breed to females of a particular breed in order to propagate the breed of interest; and
• Hybridization — the mating of individuals from different species.

What are the benefits?
The two primary benefits of crossbreeding are (1) heterosis and (2) breed complementarity. The second of these allows the cow-calf producer to combine desirable characteristics of the breeds involved in the cross. Breeds are matched based on their advantages and weaknesses, with consideration for production environments and marketing scenarios. Extensive work has been conducted at the U.S. Meat Animal Research Center (MARC), Clay Center, Neb., to characterize breed differences for beef cattle traits.
The first benefit of crossbreeding, heterosis, is a measure of the superiority of the crossbred individuals over the average of straightbreds involved in the cross. Heterosis values may be positive or negative. Reproductive traits generally show high levels of heterosis. Growth traits are intermediate, and carcass traits tend to have low heterosis values. This pattern is exactly the reverse of the general levels of heritability for these trait classes. Exceptions exist, and this should be considered a “rule of thumb” for categorizing traits. Heritability depends on additive types of gene action, while heterosis and inbreeding depression depend upon nonadditive gene action such as dominance and epistasis. Also, heterosis requires genetic differences among those individuals involved in the crosses. Hence, British crosses with Brahman and other Bos indicus types may result in more heterosis due to the greater genetic diversity among breeds.
Heterosis may be in the form of individual, maternal or paternal heterosis. As one might expect, individual heterosis in cattle is the superiority of the crossbred calf relative to the average of the purebred individuals. Maternal heterosis is the superiority of the crossbred cow over the average of the purebred cows. Paternal heterosis is the advantage of a crossbred bull over the average of the purebred males. Additional details on these concepts, as well as the genetic basis of heterosis, loss of heterosis and crossbreeding systems are found in publications named in the attached reference list.
The values in Table 1 (Kress and Nelsen, 1988) reflect the average percentages of individual, maternal and total heterosis for various traits reported in research results. Total heterosis percentages in the literature can be astounding. For example, implementation of a well-designed crossbreeding system has been estimated to increase pounds of calf weaned per cow exposed approximately 18% when compared with the average performance of straightbred cattle. An estimate for cow lifetime productivity may be as large as 25%. The impact of heterosis from a disciplined crossbreeding system is significant and large with respect to the crossbred cow and overall cow-herd productivity.



What about Crossbreeding systems and heterosis?
The typical systems include rotational and terminal mating approaches. Additional systems may include combinations of the two types, as well as composites.
Considerations for choosing a system include choice of breeds, production environment, number of breeds involved (complexity of the system), source of replacement females, marketing of calves, avoiding inbreeding, biological types, bulls for first-calf heifers, use of breed complementarity, number of breeding pastures (if natural-service sires), management, operation goals (short- and long-term), as well as other factors.
Planned crossbreeding systems are just that — well-planned. For example, various considerations (Kress and Nelsen, 1988) for simple crossbreeding systems include:

Two-breed rotation
• Two breeding pastures are required, or AI (artificial insemination).
• Individual and maternal heterosis realized (67% of maximum).
• The rotation generates replacement heifers.
• Replacements need to be identified by breed of sire.
• Use of breed complementarity is limited. Both breeds involved must be suited as a sire and dam breed (similar in size and milk production).
• Genetic improvement is dictated by the potential of the sires chosen from two breeds.
• Expected increase in calf production per cow exposed is approximately 16%.

Static terminal sire — three-breed cross
(buying crossbred F1 females)
• One breeding pasture is needed.
• Individual and maternal heterosis maximized (100%).
• Maximizes breed complementarity.
• Replacement females are purchased. (Terminal sire is used; all calves are marketed.)
• Genetic improvement is dictated by potential of terminal sires and of purchased females.
• Expected increase in calf production per cow exposed is approximately 28%.

The more breeds that are added to a crossbreeding system, the more difficult it is to manage and to maintain. Breeds should not be added to a system without a sound plan as to what bulls from the breeds contribute. If the goal is to maximize heterosis, backcrossing and thus subsequent loss of heterosis should be avoided.

What does crossbreeding the
“right way” demand?
Effective crossbreeding takes discipline. The publication Crossbreeding Beef Cattle for Western Range Environments (Kress and Nelsen, 1988) does a nice job of describing advantages and limitations of crossbreeding, as well as the various systems. A closing segment of this publication has noteworthy advice for commercial producers planning to implement a crossbreeding system. It states, “Crossbreeding is beneficial, but the benefits can be reduced by poor planning.” Suggestions include:
• Choose breeds carefully — matching genotype to environment and available management.
• Sires and replacement females should be chosen to “power” the system with superior genetics.
• Crossbreeding is not a substitute for poor management.
• Sire breeds for terminal sire systems should be chosen carefully — maximize positive complementarity and control negative complementarity (e.g., calving difficulty).
Committed producers are those who follow the plan through to completion, avoiding “bull bargains” at sale barns and curiosity with new breeds lacking expected progeny differences (EPDs). Sound choices based on research results and consideration for cow type and production environment are critical. These producers reap the benefits of crossbreeding to the greatest extent.

Are environment, milk production and cow size considerations?
Cow size is a critical component to evaluate in every herd. Larger cows have greater maintenance requirements because these females have more biologically active tissue to maintain. Cow size that cannot be supported by available feed resources requires management changes to maintain reproductive success. Stocking rate and/or supplementation may require adjustments to optimize rebreeding performance.
Standardized Performance Analysis (SPA) national results indicate that feed costs are generally the highest annual variable cost associated with the cow-calf production unit. The “specification cow” is extremely critical in the Gulf Coast region of the United States. In this area most notably, Bos indicus influence is maintained in the cow-calf operation through crossbreeding systems to enhance production efficiency.
These are just a few examples of how seedstock and commercial cow-calf producers must develop a step-by-step procedure for matching herd genetics to the natural, economic and managerial environments.

Where do Angus cattle fit in traditional crossbreeding systems?
Rotational systems are most effective with breeds that can perform as both a sire and dam breed. This is particularly important in the system’s ability to generate replacement heifers. Angus genetics are well-suited for rotational schemes, with the availability of genetics for calving ease, maternal performance, cow size, growth and carcass merit. This is a very strong point for Angus cattle and a two-breed rotational system. The Angus and Hereford breeds have been used extensively in this system.
In a three-breed terminal cross, Angus breeding is very effective as part of the F1 female. The F1 cow is not to be understated, as she is a highly efficient producer, capturing 100% of the maternal heterosis. In many cases these F1 females would be purchased. Buying replacements, as opposed to raising heifers on-farm, has been investigated extensively. Each operation must determine the breakeven point for buying vs. raising replacements. Additionally, it is imperative to state that when replacements are purchased, the health program (good or bad) of the supplier has also been purchased.
Structured recordkeeping is a crucial component for all cow-calf operators. The Angus Beef Record Service (BRS) offered by the American Angus Association is an excellent opportunity for commercial producers, regardless of breed emphasis, to track herd performance from conception to carcass. This record service has detailed reproduction and production performance summaries to use in herd productivity assessment, as well as potential decision making for future breeding plans. SPA production parameters at weaning are part of the Angus BRS summaries, including pounds of calf weaned per cow exposed.

Can Angus bulls be used as terminal sires and as maternal sires?
Variation in the Angus breed provides a tool for selecting bulls as terminal sires. The size and scope of the Angus genetic evaluation database offers “terminal sire” choices of high-accuracy bulls with genetic merit for growth (pre- and postweaning), quality grade and red-meat yield.
A sizable task for seedstock and commercial cow-calf operators is to balance quality and red-meat yield. Systematic crossbreeding can be used to combine favorable characteristics of breeds to balance carcass merit. However, the ability to identify sires within breeds whose progeny excel in both quality grade and red-meat yield remains challenging. Too often, sizable improvements in progeny marbling deposition are accompanied with excess external and seam fat, small ribeyes or both.
The Continental breeds traditionally have been touted as a necessity in terminal matings to achieve maximum red-meat yield. Yet, genetic correlations reported among carcass traits in Angus cattle (American Angus Association, Spring 2000 Sire Evaluation Report) support the use of Angus genetics to optimize carcass merit. Also, research results from Oklahoma State University (Schutte et al., 1999) demonstrated the availability of bulls in the Angus breed that can excel in quality grade and red-meat yield as simultaneously expressed in closely-trimmed boxed-beef value [$/hundredweight (cwt.) and $/head], while avoiding nonconformance characters that contribute to discounts. Using American Angus Association carcass data as adjusted by Iowa State University research for genetic evaluation, significant sire differences were detected in the Angus breed for closely-trimmed boxed-beef value.
Carcass merit differences were evaluated for the top and bottom 10% of sires based on carcass value ($/cwt.). The top 10% showed an improvement of $16.04/cwt. in carcass price in comparison with the bottom 10%. This improvement in carcass price ($/cwt.) resulted in a carcass-value advantage greater than $200/head. Progeny from the top 10% carcass-value sires had significantly (P<0.001) higher-quality carcasses with less fat, larger ribeye areas, heavier carcass weights and more desirable yield grades when compared with the bottom 10%. The improved value of the top 10% over the bottom 10% was also a direct effect of the minimal occurrence of progeny not conforming to boxed-beef fabrication specifications for one or more of the qualifying characteristics.
These examples illustrate the future potential of genetic values to influence the end product. Caution should be exercised regarding the potential effects of increased red-meat yield on reproductive performance of replacement heifers. Fortunately, the Angus database and Angus BRS open the door for a systems approach using cow size, growth and maternal performance optimums in the choices of Angus sires.
The availability of genetic tools for use in planned breeding programs continues to increase. Angus carcass evaluation EPDs are available as a tool for designing these breeding systems. The cattle for the future will not rely just on breed choices, but rather on precision seedstock selection for use in commercial programs.

Can the value of Angus cattle offset crossbreeding benefits?
Researchers have found significant differences in prices received for feeder calves (Schroeder et al., 1988; Sartwelle et al., 1996; Smith et al., 1998). Results indicate the value of Angus influence and black coat color in feeder-calf price. Smith et al. (1998) reported the extent to which characteristics of feeder cattle affected their sale price at auction in eastern Oklahoma. Characteristics included sex of calf, breed, horns, frame, muscle, fill, condition, group uniformity and health.
For example, steer calves with horns exhibited an average price discount of -$3.03/cwt. compared with polled steers. For heifers, this difference was -$1.94/cwt. For frame (using large frame size as the base), small-frame steers and heifers took the severest discounts (-$18.86 and -$20.99/cwt., respectively) compared to large-frame counterparts. The preference for larger-framed cattle was evident; however, concerns for heavy carcasses and reduced ability to grade U.S. Choice may enter in, if management to harvest is not appropriate.
For breed type, Angus cattle were used as the base to calculate breed discount and premium values. Black exotics ($2.66/cwt.) and other exotics ($1.17/cwt.) sold at a greater advantage relative to the Angus base. However, it is important to ote that “black exotic” and the perception of Angus confounds this premium advantage. The greatest discounts were received by dairy-type and Longhorn steers. Hereford calves were discounted (-$8.37/cwt. for steers and -$5.37/cwt. for heifers), as well as calves with greater than 1/4 Brahman breed type (-$5.91/cwt. steers; -$1.91/cwt. heifers). Mixed breed sale lots were discounted -$1.83/cwt. for steers and
-$0.49/cwt. for heifers.
Using Angus commercial records (1995-1999) provided by the American Angus Association, the average weaning weights for steers (n=17,080) and heifers (n=17,470) are 559 pounds (lb.) and 528 lb., respectively. Corresponding 205-day weights are 553 lb. and 515 lb. The average weaning weight from SPA data nationally is 530 lb. for steers and 498 lb. for heifers (McGrann, 1998). If commodity production is a certain producer’s focus, one cannot fault these Angus commercial weights. As for crossbreeding, if a conservative 10% heterosis increase in productivity was sacrificed by not crossbreeding, this translates to approximately 55 lb. of productivity at weaning not captured. However, effects of breed type, uniformity, retained ownership, as well as management considerations, can potentially offset the value of this weaning weight advantage. Quality grade also plays a role in assigning subsequent value to these cattle, as influenced by the U.S. Choice/Select spread for a given harvest period.
The replacement females are not to be overlooked for this scenario. The commercial Angus heifers have added value when retained in the cow herd. Exotic breed crosses generally tend to exhibit larger mature size, which can impact cost per breeding cow in poorly planned programs. Producers using Angus genetics have the potential to specify cow herd uniformity through use of EPDs for maternal performance and mature cow size.

Is more weaning weight better?
Some producers assume that increased weaning weight ensures increased profitability for the cow herd. The SPA data indicates that average weaning weight as well as pounds weaned per exposed female is lower for “low-cost” producers than “high-cost” producers (see Table 2). Commodity production for pounds of calf is not the driving force for profitability in these low-cost herds.



What do today’s branded beef programs suggest?
Particularly in the beef industry, the branded products are receiving heightened attention as a pathway to increase beef’s market share: “A branded product delivers a promise or guarantee to the consumer.” The “promise” may come in the form of taste, tenderness, product consistency, as well as juiciness, flavor, and/or satisfaction guaranteed or the product purchase is refunded.
The U.S. Department of Agriculture (USDA) provides a listing of certified and process-verified branded beef programs. These programs have carcass specifications and/or live animal requirements that must be met for branded product certification or process verification. The USDA beef and pork program listing focuses on fresh meat product and is available online at www.ams.usda.gov/lsg/certprog/industry.htm. Programs may choose to be listed and tracked with USDA, whereby their volume is recorded by an independent third party. It is not a requirement. Other branded programs exist that do not appear on the USDA summary. These are sometimes referred to as “source-verified” programs, although the extent to which verification exists varies by program.
The first and perhaps best-known of the branded beef programs is the Certified Angus Beef (CAB) Program (The CAB Program is owned and administered by Certified Angus Beef LLC, a wholly owned subsidiary of the American Angus Association). The 493 million pounds of Certified Angus Beef™ (CAB®) product sold in 1999 depicts a staggering growth in demand for this product. This growth in CAB product took place despite declining overall beef market share during that same period. Other branded beef programs have developed with similar specifications to that of CAB. The programs may not be identical in carcass specifications, but common threads for these programs exist. Specifications may include: cattle phenotype, Angus or Red Angus genotype, marbling, muscling, and hump height.
Breed. Of the 44 beef programs listed by USDA (May 17, 2000), 82% specify a breed or breed type. Also, it is not surprising that 70% are Angus or Red Angus breed-type-based specifications. Typically this means that the live requirements for cattle qualifying in a program would be related to coat color of the animal. This designation of coat color can be the initial sorting criterion for cattle potentially eligible for an Angus-breed-type branded program. Of course, the carcass specifications must also be met after this initial sort or designation.
Marbling. Branded programs may emphasize different targets. Most of those listed in the USDA summary target a quality grade benchmark of premium Choice (upper 2/3 of the Choice grade) or better. Of the 44 beef programs, 91% listed at least some marbling requirement. Fourteen programs (32%) were premium-Choice programs (Modest marbling score or better), and four programs (9%) targeted U.S. Prime (Slightly Abundant or better).
Premium-Choice and Prime programs are increasingly popular, but they provide a challenge for cattle production. The results of the 1995 National Beef Quality Audit indicated an actual quality grade consist of 1% Prime, 11% premium-Choice, 36% low-Choice, 47% Select and 5% Standard. Only 12% of the consist is available for premium beef programs. Results from the audit also suggested an ideal consist for producers to work towards: 7% Prime, 21% premium-Choice, 34% low-Choice, 38% Select and 0% Standard.
Muscling. Muscling is a typical specification required by most of the branded programs. Approximately 80% of the programs have a minimum muscling requirement. This specification is to avoid light-muscled carcasses of dairy character. Dairy cattle and high-percentage dairy-cross cattle have smaller, narrower and misshapen ribeyes.
Hump Height. Some 84% of the branded programs require a specification of less than 2 inches (in.) of hump height. This approach tends to reduce the percentage of Bos indicus influence in the carcasses. Brahman-influenced cattle have been reported to have more variation in tenderness, as measured by Warner-Bratzler shear force. A 25% increase in Brahman breed makeup has been shown to increase middle-meat shear force by 1.65 lb. (Crouse et al., 1989).

Crossbreeding systems are challenging. Can Angus emphasis help?
Ritchie et al. (1999) described the challenges of a crossbreeding system. These are summarized below.
• Difficult in small herds. Systematic crossbreeding is more easily accomplished in herds with 50 or more breeding females.
• Requires more pastures and breeds. Unless A.I. is used extensively and replacements are purchased, management is a strong consideration for the system of choice (breeding pastures, maintaining bulls of different breeds).
• Records and identification.
• Matching biological types. Mismatched breeds in a system can potentially lead to problems: (1) calving difficulty; (2) failure to efficiently run a large crossbred female when the rotation plan has her mated to a smaller breed of sire; (3) changes in biological type from generation to generation before breed stabilization has occurred in some rotational systems.
• Keeping the system going over time. Generating replacement heifers and keeping the program “systematic” and “well-planned” over time without losing heterosis can be a problem for some programs.

How can Angus cattle respond to these challenges?
Use of targeted sire selection through EPDs available in the Angus breed can be beneficial to commercial producers. This may include straightbred herds, but may assist as well those producers with high-percentage Angus breeding in their herds.
The average herd size nationally is less than 50 breeding cows. Opportunities exist for these commercial producers to capitalize on the use of EPDs in selecting Angus sires to target growth, maternal, calving ease, cow size, and carcass merit, without the need for numerous breeds. Consider the limitations faced by a producer with 40 cows, natural-service sires, one breeding pasture, limited labor and capital, and no resource for purchased replacements. Available genetic tools for sire selection can provide an innovative approach to target efficient production in this case. Rotating sire breed every four years, F1 bulls and composite lines of cattle are other options for selected programs, provided EPDs are available tools for making sire choices.
Costs of production are cited as being highest on average for herds with less than 50 cows and lowest for herds with 500-999 cows (Doye and Northcutt, 1997). Feed costs (purchased plus raised) contribute to almost half of the total cost of production for low-cost producers. High-cost producers’ feed costs and grazing costs exceed those of low-cost producers by 25% and 40%, respectively, per cow. An acceptable cow size is critical for low-cost producers to assist them in managing costs. A crossbreeding system must be carefully orchestrated in small herds in order to reap system-wide benefits. Recordkeeping through Angus BRS can be a valuable decision-making tool for commercial herds tracking their production performance.
Should small herds bother with planning for uniformity? It is definitely a consideration. One might argue the failure for premiums to substantiate this need, particularly in calves sold at weaning. However, Smith et al. (1998) reported up to a $2.35/cwt. feeder calf sale price difference in favor of lot uniformity, as surveyed in eastern Oklahoma auctions. Uniformity of size is controlled in part by the careful selection of herd sires. Along with appropriate management, EPDs are the tool to select bulls with similar growth values for weaning and yearling weight genetic merit.

Are the driving factors commodity- or consumer-targeted production?
Some contend that the small commercial operator is not a volume producer; therefore, pounds of calf produced should drive the system. Yet, increased efforts are being made among cattle organizations and Extension service teams to assist small herds in grouping calves for sale or retained ownership. It is my opinion that the commodity producers will not be the key players in the future, regardless of herd size. Consumer-targeted production has become increasingly more important, as evidenced by the growth in branded beef programs. In setting the pace for the industry, the commodity mind-set does not have a place in the long-term future of beef.
Approximately 13% of the fresh beef product today is creamed for branded premium beef programs. Examples of high-volume premium beef programs in addition to the CAB Program include Excel Sterling Silver®, Farmland Black Angus Beef, Excel AngusPride® and Wal-Mart Angus. Production volume by program is not publicly available. Estimates can be approximated relative to the CAB Program volume, with the other 43 USDA-certified/process-verified beef programs producing 50% of the volume of CAB in 1998. In 1999, about 67% of CAB Program volume was achieved by the other 43 programs. Growth in these programs continues to emphasize the need for targeted, consumer-focused production, regardless of the beef industry segment. Continued growth in branded beef is expected.
Cattle producers will have increased production challenges in the future. These “high tech” producers will enhance their understanding and application of genetic tools to improve production efficiency and consumer end-product acceptability. Partnerships among various industry segments will continue to be critical to share costs of these technologies and to target a consistent product. Vertical coordination, particularly in the beef industry, will continue to expand. This expansion will be further linked to branded programs. The “promises” from branded products will continue to grow. Consumers will expect tender beef to be the norm, with respect to their meat purchases and home-meal solutions. Research results in the genetics of tenderness should be forthcoming. Hopefully this will foster additional research for flavor and juiciness to address the overall eating satisfaction of beef. Consumer feedback on branded beef products and their desirability will become more readily accessible.

In today’s beef industry, is there a place for straightbred Angus herds?
• Straightbred and high-percentage Angus commercial herds are an option for producers with small operations and limited management opportunities. Larger cow-calf herds can benefit from this opportunity as well, provided that high-accuracy Angus sires are chosen to target various areas of the breeding program to capitalize on cow efficiency and carcass merit.
• In a well-planned crossbreeding system, with long-term goals from conception to consumer, heterosis and breed complementarity benefits will potentially meet or exceed the performance of straightbred herds.
• Angus cattle in crossbreeding systems contribute significantly to calving ease, maternal performance and carcass quality grade. Also, Angus genetics exist that exhibit optimum growth and red-meat yield.
• Commercial programs with high-percentage Angus breeding and predominantly straightbred herds, offer advantages that can favorably compensate for the lack of heterosis that would be gained through crossbreeding. This assumes that targeted Angus sires are used for a planned performance program.
• Growth of branded beef programs supports the increased use of targeted Angus genetics as part of commercial cattle production and consumer-focused beef. Futuristic approaches to beef production are moving away from the commodity mind-set.
• Angus BRS in the future will provide additional information to test beef cattle systems and their relationship to profitability, management and consumer focus.
• Angus breeders are positioned to provide a long-term commitment to the beef industry by developing and enhancing their specification seedstock through data collection, interpretation, research and application in commercial herds. As that supplier, the Angus breed must continue to bridge and foster relationships among commercial producers with a consumer-oriented focus.

References
American Angus Association. 2000. Spring 2000 Sire Evaluation Report. American Angus Association. Saint Joseph, MO.
Buchanan, D.S., A.C. Clutter, S.L. Northcutt, and D. Pomp. 1993. Animal Breeding: Principles and applications. Fourth edition. Oklahoma State University.
Buchanan, D.S., and S.L. Northcutt. 1996. The genetic principles of crossbreeding. Great Plains Beef Cattle Handbook.
Bullock D. 1999. Crossbreeding: The Lost Art? Managing heterosis in small herds. Proceedings of Beef Improvement Federation. Roanoke, VA.
Crouse, J.D., L.V. Cundiff, R.M. Koch, M. Koohmaraie, and S.C. Seideman. 1989. Comparisons of Bos indicus and Bos taurus inheritance for carcass beef characteristics and meat palatability. J. Anim. Sci. 67:2661.
Doye, D. and S.L. Northcutt. 1997. Cow/calf financial and production performance: What we are learning from SPA data. OSU Extension Facts. F-231.
George, M.H., J.D. Tatum, K.E. Belk, and G.C. Smith. 1999. An audit of retail beef loin steak tenderness conducted in eight U.S. cities. J. Anim. Sci. 77:1735.
Kress, D.D, and T.C. Nelsen. 1988. Crossbreeding Beef Cattle for Western Range Environments. University of Nevada-Reno and USDA (TB-88-1).
McGrann, J. 1998. Standardized Performance Analysis Report Card. Texas A&M University.
Ritchie, H., D. Banks, D. Buskirk, and J. Cowley. 1999. Crossbreeding systems for beef cattle. Michigan State University Extension Bulletin E-2701.
Sartwelle III, J.D. et al. 1996. Cooperative Extension Service, Kansas State University. MF-2142 (revised).
Schroeder, T. et al. 1988. Kansas Agricultural Experiment Station. Report of Progress 547.
Schutte, B.R., S.L. Dolezal, H.G. Dolezal, and D.S. Buchanan. 1999. Characterization of boxed beef value in Angus field data. OSU Anim. Sci. Res. Rep. pp. 32-40.
Smith et al. 1998. Effect of selected characteristics on the sale price of feeder cattle in eastern Oklahoma. Oklahoma Cooperative Extension Service. Oklahoma State University. E-955.
Suther, S. 1999. Certified Angus Beef Program press release packet. Certified Angus Beef Program.
Thrift, F.A. 1992. Animal Breeding: Mating systems applicable to genetic improvement of livestock. Department of Animal Sciences. University of Kentucky, Lexington.
USDA. 1999. USDA Certified and Process Verified Programs. USDA Agricultural Marketing Service, Washington, D.C. www.ams.usda.gov/lsg/certprog/industry.htm