Robert R. Schalles & Keith O. Zoellner, Using EPDs in a commercial herd, Kansas State University, September 1993

Schalles, Robert R.

Zoellner, Keith O.

K-State Research Exchange

Using EPDsin aCommercial HerdR. R. Schalles and K. O. ZoellnerDepartment of Animal Sciences and IndustryKansas State UniversityManhattan, KS 66506Outdated Publication, for historical use. CAUTION: Recommendations in this publication may be obsolete.Today, beef cattle producers have the best toolsfor specification production ever available. Thebiggest problem that cattlemen have is definingthe specifications. Many traits are important whenconsidering the production system fromconception to consumption. Genetics plays animportant role in some of these traits whilemanagement is more important in others.All cattlemen, purebred and commercial, needto be conscious of the ultimate product of theproduction system—quality beef at a reasonableprice. It all starts at conception of the calf.Reproduction failures are primarily due tomanagement failures, most often inadequatenutrition. However, the nutrition requirements ofa cow are determined by growth rate when she isyoung, body size that must be maintained, milkproduction level, the need to regain fat if she isthin, and the effective temperature she must live2in, among other factors. These factors, alongwith the constraints put on the ultimate product,dictate production goals.In an environment where nutritional resourcesare adequate, as is the case in many areas of theU.S., production levels can be quite high.However, as production levels increase, the levelof nutrition must also increase to meet therequirements. Therefore, producers shouldattempt to match their beef cow’s genetic potentialfor milk and growth with their environment.However, producers should keep in mind thatpurchased feed is a resource that is alwaysavailable and should be considered when it iseconomically feasible.With these facts in mind, the producer needs todetermine the production goals for his individualoperation. What is the optimum level ofproduction for each trait?Outdated Publication, for historical use. CAUTION: Recommendations in this publication may be obsolete.Direct Calving EaseDirect calving ease (the calf's ability to be born) is negativelycorrelated with birth weight, weaning weight, yearling weightand mature size. Since heavier weaning and yearling weightsare generally more profitable, each producer needs to determinethe lowest level of direct calving ease that he can tolerate.Currently, only the Gelbvieh and Simmental breed associationsproduce EPDs for this trait. The Simmental breed presents thisinformation as an EPD in terms of percent of unassisted birthsfrom Simmental cows. The Gelbvieh presents the sameinformation in terms of a ratio with 100 being the base anddeviations above and below. Only first calf two-year-olds areevaluated since very few older cows have dystocia. However,this evaluation is extended to what would be expected in maturecows. A producer who has small mature size cows will probablywant a higher level of direct calving ease than one with largercows.Birth WeightBirth weight is negatively related to direct calving ease butpositively related to weights later in life. A producer who desiresheavy weaning and yearling weights would want as heavy a birthweight as possible without causing dystocia problems. The EPDfor birth weight is presented in pounds of calf as a deviation fromthe average in the year each breed has selected as their base year.Each cow herd will have a certain threshold where heavy birthweights will cause trouble and the producer must determine thislevel.Weaning Weight and Yearling WeightWeaning weight and yearling weight EPDs are presented inpounds of calf and heavyweights are often desired. However, theweight must match the level of nutrition available to both the cowand calf. Cattle with extremely large weaning or yearling weightEPDs will not express their genetic potential for growth withinadequate feed. The nutrition level of the herd needs to beevaluated when determining the optimum EPD levels for thatherd. Another factor that needs to reconsidered is the age at whichcalves are marketed. If the producer sells calves at weaning, theweaning weight EPD becomes more important than the yearlingweight EPD. However, if the producer retains ownership of hiscalves through the feedlot to the packer, yearling weight EPDsbecome more important.Maternal Calving EaseMaternal calving ease EPD (the cows ability to have a calf) arepresented by the Simmental and Gelbvieh breeds and expressedin the same unit as direct calving ease. Maternal calving ease ispositively related to cow size and pelvic area. Larger cows with abig pelvic area can have a given size calf with less trouble than asmall cow. Generally, a large maternal calving ease EPD isdesirable, however mature cow size must be kept in mind whenselecting the extremes.MilkMilk EPD is presented in terms of calf weaning weight that iscaused by milk. Calves with higher weaning weight EPDs canutilize more milk than those with less genetic ability for growth.Producers need to remember that more milk takes more cow feed!Cows with the genetic ability for high milk production but whodon’t have sufficient nutrition for that level of milk productionwill use stored body fat and become too thin to rebreed. Thisresults in open cows, not because of poor reproduction butbecause the genetic ability for milk production is too high for thenutrition level provided. This has been a particular problem withcrossbred Simmental and Gelbvieh cows when fed at the samelevel as British breed cows. Research has shown that Simmentaland Gelbvieh cows give considerable more milk than most otherbeef breeds. The optimum milk EPD for these breeds in manycommercial herds may be negative unless adequate nutritionis provided.Maternal Weaning WeightMaternal weaning weight EPD is a combination of the weaningweight and milk EPDs. It provides a convenient index to indicatethe expected pounds of weaning weight due to both sources. ThisEPD maybe more important to commercial producers than eitherweaning weight or milk EPD separately.Scrotal CircumferenceYearling scrotal circumference of bulls is an important trait forseveral reasons. The Hereford breed presents EPD for this trait incentimeters. Bulls with larger yearling scrotal circumference tendto produce more volume of semen than those with smaller scrotalcircumferences. The Society of Theriogenology has established aminimum yearling scrotal circumference of 30 centimeters forsatisfactory breeding. However, perhaps even more important isthe relationship of yearling scrotal circumference to rate ofmaturity. Bulls with larger yearling scrotal circumferences producedaughters that reach puberty earlier and obtain a larger percent oftheir mature size at an earlier age. This could be an advantage toboth replacement heifers and finishing cattle in the feedlot. Scrotalcircumference is a highly heritable trait and, therefore, selectioncan result in rapid change. However, there is an optimum levelwith this trait also. There is little advantage of heifers reachingpuberty before they are weaned and there may be a severedisadvantage if the heifer becomes pregnant while nursing herdam. The Simmental, Gelbvieh and Angus tend to be earlymaturing breeds.Frame ScoreFrame score is a trait that has received considerable attentionduring the past 40 years, from very small to very large. TheHereford breed presents EPD for yearling height in inches. Whenthe desired carcass weight and mature cow size are taken intoconsideration, most research indicates that a frame score of at least5 and less than 8 are usable in commercial production systems.3Outdated Publication, for historical use. CAUTION: Recommendations in this publication may be obsolete.Frame score is a highly heritable trait and the individuals ownframe score is a reasonably good indicator of its genetics for this trait.Gestation LengthGestation length has a .26 correlation with dystocia score,probably caused by the fetus growth rate during the last few weeksof gestation. The Gelbvieh breed presents an EPD for this trait,based on animals with known breeding and calving date. Selectionfor shorter gestation length will allow a longer postpartum intervalbetween calving and rebreeding as well as some reduction ofdystocia.Carcass TraitsSeveral breeds are actively accumulating carcass data toproduce EPDs. The Angus breed, for example, presents EPDs forcarcass weight, marbling and ribeye area. Most breeds have onlylimited data available, however this will probably change in thenear future. Several breeds have active programs to collect carcassdata and the new NCA Carcass Data Collection Service shouldhelp in these efforts.Other TraitsMany other traits have varying degrees of importance incommercial production, including structure soundness of feet,legs, udder, etc., horned-polled, disposition and others. Some AIfirms and individual ranches have developed physical traitevaluation programs for many of the structural traits, however atthis time only progeny averages for specific bulls are available.Most of these traits also have an optimum level for satisfactoryproduction rather than desiring the maximum or minimum levels.In addition, some producers may desire certain characteristics thathave little or no influence on efficient production of desirablebeef.Breed SelectionAfter a commercial producer has established his goal forproduction it is time to select the bulls. The first choice is to selectthe breed or breeds. There are over 70 breeds of cattle from whichto select. A major consideration should be which breeds providethe information needed to make a wise choice. EPDs should be anecessity and reduces the number of breeds considerably. Theaccuracies of the EPDs on young bulls that commercial producersusually buy are going to be low. However, EPDs are still a muchmore accurate evaluation of an animal than the individuals ownperformance. This is because the individuals own performancefor that trait is taken into consideration as well as the individualsperformance in correlated traits and the performance of relatives.The average of progeny from a group of bulls will be very closeto the average of the EPDs of that group.The strengths and weakness of the breeds should be considered.Table 1. is based on research at the USDA Meat Animal ResearchCenter, Clay Center, NE, and compares the average animals bornin 1991 adjusted to the average EPD for the breed.Table 1. Comparison of Average Weights by BreedsAdjusted to 1991 Birth Year Average EPD.Birth Wean. Year. MaternalBreed Wt. Wt. Wt. Milk   Wean. Wt.Angus 77.6Brahman 87.8Charolais 86.0Gelbvieh 87.3Hereford 81.4Limousin 83.1Maine Anjou 87.8P. Hereford 80.3Pinzgauer 82.4Salers 80.9Shorthorn 83.5Simmental 86.0* EPDs are not available441447458465442450458450440464461471810744819822800798826806783830832860-8.0 48026.0 517-3.0 49422.0 523-16.0 473-13.0 480-40.1 453-1.0 4876.0 5058.0 50620.0 523As an example, the average Simmental born in 1991 would beexpected to produce daughters with milking ability for 28.0 lbsmore calf weight at weaning than the average Angus born in 1991(20.0 + 8.0). The average Angus born in 1991 would be expectedto produce calves that are 8.4 lbs lighter (86.0 - 77.6) at birth thanthe average Simmental. The average Gelbvieh would be expectedto produce calves 3 lbs heavier (822 - 819) at yearling than theaverage Charolais born in 1991.Because of the genetic trend within most breeds and theselected base year which is set to zero, the average of calves bornin the current year will usually not be zero. Almost all breeds haveincreased in size (birth, weaning and yearling weights) over thelast 20 years. Several breeds have also increased the average levelof milk production. Therefore, depending on where the base is set,the average EPD of calves born in a particular year will not be zero.Table 2. gives the average EPD of calves born in 1991 for severalbreeds.Table 2. Average EPD of Calves born in 1991 by BreedBirth Wean. Year. MaternalBreed Wt. Wt. Wt. Milk   Wean. Wt.AngusBrahmanCharolaisGelbviehHerefordLimousinMaine AnjouP. HerefordPinzgauerSalersShorthornSimmental3.2 22.2. 5 4.2.9     2.5.3     4.42 . 2 25.3.6         3.6.5         4.33.3 21.0-1.1 -.5.7     6.61.8 11.1.5     5.838.27.53.68.240.37.47.333.8-1.010.818.310.07.7 18.82.7     4.9-1.8 -.62.0     4.26.9 19.5.1 1.9.6 11.1-.3 -.53.2     6.52.0     7.5-.2     2.74Outdated Publication, for historical use. CAUTION: Recommendations in this publication may be obsolete.Across breed EPDs can be calculated by taking the differencebetween each breed and the breed chosen as the base from Table1., and subtracting the average difference between EPDs of eachbreed and the chosen base breed from Table 2. (see appendix I).Bull Selection Within a BreedAfter a commercial producer has determined the goals for hisproduction system, more than one breed can be selected to use ina cross breeding system. As an example, consider that you havebeen using Angus bulls with the average EPDs shown in Table 3.Perhaps you want to use either Simmental or Gelbvieh bulls thatwould increase milk, yearling weight and maternal calving easewith little change in birth weight.Table 3. An Example of Comparing Bulls for a CrossbreedingProgramCurrent New NewTrait Angus Bulls  Gelbvieh SimmentalAverage Bulls BullsDirect Calving Ease(H) 98 to 102 -2 to 2Birth weight 4 -9 to -4 -7 to -2Weaning weight 30 8 to 18 4 to 14Yearling weight 40 38 to 53 2 to 17Maternal Calving Ease(H) 100 to 105 3 to 9Milk 10 -6 to +4 -6 to 4Maternal Weaning Weight      25 -8 to 2 -9 to 1* Calving ease EPDs are not available for the Angus breed.When the average differences between breeds (Table 1.) andthe differences in the base to which they are set (Table 2.) are takeninto consideration, the new Simmental or Gelbvieh bulls wouldcause an increase milk production from their daughters to producefrom 20 to 30 lbs. heavier calves at weaning. The yearling weightof the calves sired by the new bulls should be increased by 40 to55 lbs., yet birth weight would increase no more than 5 lbs.Maternal calving ease is not available for Angus, but the range, 3to 9 percent more unassisted calves in Simmental and 100 to 105in Gelbvieh, encompass the average of calves born in these breedsin 1991. When comparing the desired EPD of the new Simmentalor Gelbvieh bulls to the average animal born in 1991, the negativebirth weight EPD is slightly below the average animal born in1991 in both breeds and weaning weight EPD is slightly above.The maternal weaning weight encompass the averages, howeverthe yearling weight EPD is above the average born in 1991 forboth breeds. The milk EPD is below the average in both breeds.If the bulls were to be used on heifers the cattlemen may wantto sacrifice some growth for greater direct calving ease andsmaller birth weight EPDs. Bulls with low birth, weaning andyearling weight EPDs of any breed, selected to breed heifers forcalving ease, should be considered as terminal sires and noreplacement heifers kept, since the calves will probably lack thedesired growth. After the desired EPD ranges are determined,then the price of the bulls to obtain the set level of genetics fromdifferent breeds needs to be considered in an effort to make aneconomic decision.The Future is NowToday’s commercial cattlemen have the best tools everavailable to make selection decisions. The biggest job eachindividual producer has is to determine the optimum productionlevel to produce the desired product at a reasonable price. Manydifferent breeds could be incorporated into a systematiccrossbreeding program, however, it is best to keep it simple byusing only two or three breeds, or using an F 1 bull, if EPDs areavailable. The strength and weakness of each breed need to beconsidered, and then determine the EPD ranges needed for eachbreed for the specific herd. There is a lot of diversity bothbetween and within breeds. When the genetic levels have beendetermined it is extremely important to match the management(especially nutrition) to the genetics for profitable production ofthat desired product.5Outdated Publication, for historical use. CAUTION: Recommendations in this publication may be obsolete.Robert R. SchallesProfessorAnimal BreedingKeith O. ZoellnerExtension SpecialistBeefCooperative Extension ServiceKansas State UniversityManhattan, KansasMF-1082 September 1993Issued in furtherance of Cooperative Extension Work, acts of May 8 and June 30, 1914, as amended. Kansas StateUniversity, County Extension Councils, and United States Department of Agriculture Cooperating, Richard D.Wootton, Associate Director. All educational programs and materials available without discrimination on the basis ofrace, color, national origin, sex, age, or disability.File Code: Animal Science: Beef 9-93—8MOutdated Publication, for historical use. CAUTION: Recommendations in this publication may be obsolete.

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