List Seven Points That Should Be Considered When Selecting a Beef Breed

May 27, 2022 Post a Comment

EPD Basics and Definitions

Matthew Spangler

University of Nebraska, Lincoln

mspangler2@unl.edu

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Summary:

EPDs represent the genetic component of an animal's phenotype that is expected to be passed on to the next generation. Studies take shown that using EPDs are seven to nine times more effective than selecting based on actual phenotypes. While well-nigh producers recollect of increasing the economic efficiency of their functioning past changing management systems (i.e., grazing schemes, calving dates, etc.) or utilizing different nutritional programs, the importance of correct genetic selection is all too often overlooked. If selection is based on nongenetic factors, as is the case when selecting on actual or adjusted measurements instead of EPDs or economic indexes, and so an inefficiency is automatically built into the cow/calf enterprise. Information technology is critical to empathize how to interpret EPDs and to know breed averages, and exist able to apply percentile ranks in gild to place potential sires that fit the desired breeding objective.

Introduction

Expected Progeny Differences (EPDs) let for the comparison of animals within a breed for their genetic potential every bit parents for a given trait. EPDs have existed in the beef industry for decades and their use has produced intended genetic change in many traits. Yet, some producers are still reluctant to rely on EPDs when making option decisions; presumably considering of a general lack of understanding of how EPDs are derived and their interpretation.

Nuts of an EPD

Too often seedstock producers and bull buyers get caught upwardly in the actual weights, ultrasound information, etc., when selecting sires. EPDs provide a mensurate by which animals inside a breed can be compared to one some other for their genetic potential as parents for specific traits. EPDs comprise multiple sources of data, including full full-blooded, an animal's own record, genomic data, and progeny information. As additional sources of information become available, the accurateness of the EPD value increases. Prior to a National Cattle Evaluation (NCE), animals are given interim EPDs. During a genetic evaluation, all pedigree data would exist included.

Pedigree estimate:

Sire EPD = 0.20	Dam EPD = 0.ten
Progeny EPD = (0.xx + 0.10)/two = 0.15

Pedigree guess + animal record:

EPD _I = (0.5*EPD _Southward ) + (0.5*EPD _D ) + (0.5 *Mendelian Sampling Outcome)

Where EPD_I is the EPD for some private I, EPD_S is the EPD for the sire of animal I, EPD_D is the EPD for the dam of animal I. The phenomena of Mendelian sampling arises due to the fact that each parent passes a sample one-half of its alleles to its offspring and every allele has an equal likelihood of being passed on. This upshot tin can be quantified using contemporary group deviations and is a measure of how much ameliorate or worse an animal is compared to the boilerplate of his parents. One could envision a scenario in which an creature could receive just the most desirable alleles from both parents, resulting in a favorably big Mendelian sampling effect or the exact opposite, which could issue in an unfavorably large sampling result. Perhaps the best example is a set of flush mates. Although all of them accept the same pedigree judge, they differconsiderably in terms of functioning and consequently their EPDs, once they take a tape, differ due to Mendelian sampling. Current methodology behind the estimation of Mendelian sampling effects tin be found in the Beefiness Improvement Federation Guidelines at http://beefimprovement.org/content/uploads/2015/08/REVISED-MasterEd-BIF-GuidelinesFinal-08-2015.pdf.

When using EPDs, it is important to sympathize that the role of EPDs is to provide a measure out of comparing within a breed. To compare animals across breeds, estimates from the U.South. Meat Animal Enquiry Center (MARC) tin can aid in determining differences between EPDs of different breeds (Table I). These across breed aligning factors, adjusted to an Angus basis, are updated annually and can be found at http://beefimprovement.org/library-2/convention-proceedings. In that location are beyond-breed genetic evaluations in beingness (e.g., International Genetic Solutions; IGS) in beef cattle but producers should continue to employ the USMARC derived adjustment factors if available to correctly conform for breed effects.

EPDs Compared to Raw Data and Ratios

Many producers mistakenly identify more emphasis on raw measurements than EPDs. Raw measurements include the confounded effects of genetics and environment, and consequently, the genetic ability of the animal is unknown. Beneath is a very simplistic equation describing the phenotype of an animal.

Where P is the phenotype, G is the genetic effect, and E is the ecology consequence.

The phenotype is what is seen, or measured, such as the actual browse information for REA or International monetary fund. Both genetics and the surround influence these values, and considering we are interested in identifyinganimals based on their potential every bit parents, the environment should not exist included in the tool used to select animals. Furthermore, actual scan figures are non comparable from beast to animal since they take not been adjusted nor do they provide any clue as to how much better or worse an animal is compared to others. A gimmicky group ratio does allow for comparison of animals and provides an idea of how much better or worse a particular animal's adjusted tape is compared to others within the same contemporary group. The problem is that a ratio is not useful in comparing animals beyond herds or exterior of the defined contemporary group.

The genetic and environmental components of phenotype can be further divided into additive (A), authorization (D), and epistatic (I) genetic furnishings and both permanent (P) and temporary (T) environmental effects.

P = 1000 _A + G _D + Grand _I + East _P + Due east _T

Generally speaking, we only go concerned with permanent ecology effects when we recall nigh the environmental influence a dam has on her offspring (e.thousand., a young dam develops mastitis and loses function in one quarter, resulting in reduced weaning weights of subsequent offspring). Contemporary groups account for some of the temporary environmental effects. In genetic evaluations we are able to predict the additive genetic component, which is presented as an EPD. This is used in determining the heritability (h2), which is simply the fraction of the variance in phenotype (σ2P) that is explained or acquired past variation in additive values (σ2A). The heritability can be idea of as the average phenotypic differences or superiority that is likely to be passed on genetically to the next generation.

The objective of buying a bull is to purchase an animal that will enhance the genetics of his offspring. Choice based on a raw phenotypes such every bit actual weights or ultrasound scan values places selection pressure not but on the genetic potential of an beast but also on environmental influences (herd, year, season, direction, etc.). If y'all wait at two drastically different management scenarios: 1) fodder tested bulls, and ii) high concentrate fed bulls, information technology would be expected that the high concentrate bulls would have greater intramuscular fat pct (IMF) figures. The question remains, are the more desirable IMF browse figures due to genetics or the fact that they received more feed? We know that the environmental benefits volition not exist passed from parent to offspring, simply the genetics. Consequently, selection based on EPDs will help sort the wheat from the chaff in that EPDs eliminate ecology differences and quantify genetic differences.

EPD Definitions

	Balderdash A	Bull B
Calving ease directly	ten	6
Birth weight	2.0	three.five
Weaning weight straight	20	22
Yearling weight	40	52
Yearling elevation	0.three	0.vi
Milk	three	-2
Maternal weaning weight	13	9
Gestation length	-0.1	one.one
Calving ease maternal	4	6
Mature daughter height	0.5	1.0
Mature daughter weight	0	30
Scrotal circumference	0.1	-0.45
Heifer pregnancy	6	9
Udder	0.4	-0.ane
Teat	0.five	0
Carcass weight	ii.0	20
Percent retail cuts	0	0.two
Marbling	0	-0.3
Imf	3.0	1.0
Rib-eye area	0.06	1.vi
Fatty thickness	-0.01	-0.09
Rump fat thickness	-0.03	-0.10
Tenderness	-0.01	0.1
Days to finish	xv	x
Residual average daily gain	-0.1	0.05
Residual feed intake	-0.05	0.10
Dry matter intake	0.2	0.iv
Stayability	ten	6
Maintenance free energy	0	10
Docility	6	ii

Calving ease direct — Bull A should take four percent more unassisted births from first-dogie heifers than Bull B. While birth weight is an indicator of calving ease, it does not tell the whole story. Calving ease is an economically relevant trait. Producers should not use both birth weight and calving ease EPDs together since the birth weight EPD is already used in the adding of calving ease.

Birth weight — Balderdash B'south calves would be on average 1.5 pounds heavier at nascence. Keep in mind that when crossing breeds, heterosis or hybrid vigor tin increment birth weights over a straightbred average. When selecting bulls to apply on heifers, the economically relevant trait is calving ease and producers should focus on calving ease EPD rather than nascency weight EPD.

Weaning weight direct — Calves from Bull B should average 2 pounds more on adjusted weaning weights because of boosted growth. Considering of the low accurateness associated with yearling bulls, the amount of emphasis placed on such a pocket-size departure should be limited. These EPDs are nearly the same even if the accuracies were high.

Yearling weight — Bull B'south calves should average 12 pounds heavier at one twelvemonth of age.

Yearling top — Bull B's calves should be 0.3 inches taller on average at a year of age compared to the offspring of Bull A. Height measurements are taken at the hip. Top (the actual measurement and not the EPD), forth with age, is used to calculate frame score.

Milk — Daughters from Bull A should produce calves that are 5 pounds (the difference betwixt +3 and -2) heavier at weaning. This is not a measure of pounds of milk simply rather weaning weight due to milk product. This five pounds, unlike the weaning weight figure attributed to growth from the balderdash, is the issue of differences in the daughters' milk product and mothering ability. Excessively loftier milk levels in low input environments should be discriminated against due to increased nutrient requirements of cows.

Total maternal (maternal weaning weight) — Daughters from Bull A will produce calves that are iv pounds heavier at weaning on boilerplate because of their combined genetics for growth and milk. This is a calculated figure of one-half the bull's weaning weight straight EPD plus his milk EPD. For example, Bull A has a maternal weaning weight value of xiii, which is equal to one-half of his weaning weight straight EPD (20/2=10) plus his milk EPD (iii).

Gestation length — Calves from Balderdash A should take a one-day shorter gestation.

Calving ease maternal — Bull B's daughters should calve as starting time-calf heifers with 2 percent more than unassisted births (half dozen-4) than the daughters of Bull A.

Mature height — Bull B'south daughters should be .5 inches taller at maturity.

Mature weight — Bull B'south daughters should exist xxx pounds heavier when mature.

Scrotal circumference — Bull calves from Bull A should have 0.55 centimeters larger adjusted scrotal circumferences. Scrotal circumference is an indicator of the age of maturity of a balderdash's daughters. Bulls with larger scrotal circumference should have daughters that attain puberty before. It is also an indicator of the chapters for sperm production of a bull.

Heifer pregnancy — Daughters of Bull B are three per centum more probable to become pregnant as heifers.

Udder score — Daughters of Bull A are expected to accept udders that score 0.5 points higher on average compared to daughters of Bull B. A higher udder score is indicative of a tighter udder interruption (more desirable).

Teat score — Daughters of Bull A are expected to accept teats that score 0.5 points higher on average compared to daughters of Bull B. A higher teat score is indicative of smaller (length and circumference) teats.

Carcass weight — Bull B should produce calves that accept 18 pounds more adjusted carcass weight.

Percent retail production — The calves from Bull B should yield 0.2 percent more closely trimmed, boneless retail cuts from the circular, loin, rib, and chuck. Some breeds may report a Yield Grade (YG) EPD. The same factors (back fat, ribeye surface area, and carcass weight) would be included, just a lower YG is more desirable as opposed to per centum retail production where a higher value is more desirable. In either pct retail product or YG, fat thickness contributes the most to these ii calculations. Consequently, selecting for decreased YG or increased percent retail product will lead to bacteria animals so circumspection should be used to avoid extremely lean replacement females.

Marbling — Calves from Bull A should have a 0.three higher marbling score. Marbling scores range from ane.0, which is devoid of marbling and a utility quality grade to ten.ix, which is abundant marbling and a prime number + quality form. For example, if calves sired by Bull B had a marbling score of 5.0, then nosotros would expect calves sired by Bull A to have a marbling score of 5.3. Ultrasound EPDs were calculated for a number of breeds for traits of rib-centre area, fatty, and intramuscular fat (Imf), which is correlated to marbling, simply now the majority of breeds use these ultrasound measurements in the calculation of carcass EPDs. So, instead of seeing both an IMF EPD and a marbling EPD you just see the marbling EPD, but it has ultrasound measurements included in the calculation.

International monetary fund — Calves from Balderdash A should produce calves with 2% more than intramuscular fat than calves sired by Bull B. Intramuscular fat pct (International monetary fund) is measured by ultrasound and is a proxy for carcass marbling. About breeds incorporate this measurement into their corresponding carcass marbling EPD equally an indicator trait.

Rib-eye area — At a given end bespeak, calves from Bull B should have rib-eye areas that are ane.54 square inches larger than Bull A's calves.

Fat thickness — At a given end point,calves from Bull A should be 0.08 inches fatter when measured at the 12th rib. This would be less desirable on a carcass animal, merely extremely lean females going back into a cowherd may besides be undesirable.

Rump fat thickness — At a given stop point, calves from Bull A should be 0.07 inches fatter when measured between the hooks and pins. This measurement is taken solely via ultrasound.

Tenderness — Calves sired by Bull A should produce meat that is more tender than that of calves sired by Bull B past 0.2 pounds of shear force. Tenderness is measured by Warner Bratzler Shear Force (WBSF) that is reported in the pounds of force required to cutting through a ane-inch thick piece of meat. A lower value is more desirable.

Days to stop — Calves sired by Bull B should spend five fewer days on feed to reach a constant fat endpoint.

Residue average daily proceeds — Calves sired by Bull B should gain 0.15 pounds per day more those sired by bull A when fed the aforementioned amount of feed during the post-weaning phase.

Residual feed intake — Calves sired by Bull A should consume 0.15 pounds less feed per 24-hour interval than those sired by bull B given the same levels of proceeds during the post-weaning stage. Note that selection based on residual boilerplate daily gain and residual feed intake may non atomic number 82 to the same bull selection decisions.

Dry matter intake — Calves sired by Bull B are expected to consume 0.2 pounds more feed per mean solar day on a dry out matter ground compared to those sired by Balderdash A.

Stayability — A measure of reproductive longevity. Daughters of Bull A are four percent more than probable to stay productive in the herd to age 6.

Maintenance free energy — The Crimson Angus Association of America calculates a Maintenance Energy (ME) Expected Progeny Difference (EPD) that indicates differences in the Mcal/month needed for maintenance due to mature size (corrected for torso condition score) and milking ability (The Rancher'due south Guide to EPDs is bachelor at www.redangus.org). A much simpler manner to think of it is that a bull with a ME EPD of +10 compared to ane that is +0 volition produce daughters that will require approximately eleven more pounds of boilerplate quality fodder permonth (assuming average quality provender = .86Mcal/lb).

Docility — Bull A should sire four percent more calves that take a temperament in the most docile score than Balderdash B. The bodily measurement of docility is recorded either at weaning or yearling (depending on the brood association) and is categorized as the animals' behavior every bit they enter, are restrained in, and leave the chute.

Beef Improvement Federation (BIF) temperament scoring system

1. Docile — Mild disposition; gentle and hands handled. Stands and moves slowly during processing, undisturbed, settled, and somewhat deadening and does not pull on the headgate when in the chute; exits the chute calmly.

ii. Restless — Quieter than average only slightly restless, might exist stubborn during processing, might try to dorsum from the chute, pulls back on the headgate, some tail flicking, exits the chute promptly.

iii. Nervous — Typical temperament is manageable merely nervous and impatient with a moderate corporeality of struggling, motility, and tail flicking equally well as repeated pushing and pulling on the headgate; exits the chute briskly.

4. Flighty — Wild, jumpy, and out-of-control, quivers and struggles violently, might bellow and froth at the rima oris, continuous tail flicking, defecates and urinates during processing, frantically runs the argue line and might bound when penned individually, exhibits long flight distance, and exits the chute nervously.

5. Aggressive — Similar to Score 4 just with added aggressive behavior, fearful, extreme agitation, continuous movement that might include jumping and bellowing while in the chute, exits the chute frantically and might exhibit attack behavior when handled lone.

6. Very Aggressive — Extremely aggressive temperament. Thrashes about or attacks wildly when confined in small, tight places. Pronounced attack beliefs.