What Is the Birthweight of Beef Cattle

 EPD Nuts and Definitions

  Matthew Spangler

  Academy of Nebraska, Lincoln

  mspangler2@unl.edu

*Click here for printable pdf version.

Summary:

EPDs represent the genetic component of an animal's phenotype that is expected to be passed on to the adjacent generation. Studies have shown that using EPDs are 7 to nine times more effective than selecting based on actual phenotypes. While about producers think of increasing the economic efficiency of their functioning by irresolute direction systems (i.e., grazing schemes, calving dates, etc.) or utilizing different nutritional programs, the importance of right genetic pick 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, then an inefficiency is automatically built into the cow/calf enterprise. It is critical to sympathize how to interpret EPDs and to know breed averages, and be able to use percentile ranks in club to identify potential sires that fit the desired convenance objective.

Introduction

Expected Progeny Differences (EPDs) allow for the comparing of animals inside a breed for their genetic potential as parents for a given trait. EPDs accept existed in the beef industry for decades and their use has produced intended genetic alter in many traits. However, some producers are nevertheless reluctant to rely on EPDs when making selection decisions; presumably because of a general lack of understanding of how EPDs are derived and their interpretation.

Basics of an EPD

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

Pedigree estimate:

Sire EPD = 0.20	Dam EPD = 0.10
Progeny EPD = (0.twenty + 0.x)/two = 0.15

Pedigree estimate + animal tape:

EPD _I  = (0.5*EPD _S ) + (0.5*EPD _D ) + (0.5 *Mendelian Sampling Consequence)

Where EPD_I is the EPD for some individual 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 existence passed on. This effect tin can be quantified using contemporary group deviations and is a measure out of how much amend or worse an creature is compared to the average of his parents. Ane could envision a scenario in which an beast could receive simply the most desirable alleles from both parents, resulting in a favorably large Mendelian sampling upshot or the exact opposite, which could issue in an unfavorably big sampling outcome. Perchance the best example is a set of affluent mates. Although all of them accept the same full-blooded approximate, they differconsiderably in terms of performance and consequently their EPDs, one time they have a tape, differ due to Mendelian sampling. Current methodology behind the estimation of Mendelian sampling effects tin can exist found in the Beef 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 understand that the function of EPDs is to provide a measure of comparing within a breed. To compare animals across breeds, estimates from the U.Due south. Meat Animal Inquiry Centre (MARC) tin aid in determining differences between EPDs of different breeds (Table I). These across breed adjustment factors, adjusted to an Angus footing, are updated annually and can be found at http://beefimprovement.org/library-2/convention-proceedings. At that place are beyond-breed genetic evaluations in beingness (e.g., International Genetic Solutions; IGS) in beef cattle but producers should go along to utilise the USMARC derived adjustment factors if available to correctly adapt for breed effects.

EPDs Compared to Raw Data and Ratios

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

Where P is the phenotype, G is the genetic effect, and E is the environmental upshot.

The phenotype is what is seen, or measured, such as the actual browse data for REA or IMF. Both genetics and the environment influence these values, and because we are interested in identifyinganimals based on their potential as parents, the surroundings should not be included in the tool used to select animals. Furthermore, actual scan figures are not comparable from animal to animal since they accept not been adjusted nor do they provide any clue every bit to how much amend or worse an creature is compared to others. A contemporary group ratio does let for comparing of animals and provides an idea of how much better or worse a particular brute'southward adapted record is compared to others within the same contemporary group. The trouble is that a ratio is not useful in comparison animals beyond herds or exterior of the divers contemporary group.

The genetic and ecology components of phenotype tin can exist farther divided into additive (A), authorisation (D), and epistatic (I) genetic effects and both permanent (P) and temporary (T) ecology furnishings.

P = G _A  + One thousand _D  + Grand _I  + E _P  + Due east _T

Generally speaking, nosotros only become concerned with permanent environmental effects when we think about the environmental influence a dam has on her offspring (e.grand., 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 ecology 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 but the fraction of the variance in phenotype (σ2P) that is explained or acquired by variation in additive values (σ2A). The heritability can be thought of as the average phenotypic differences or superiority that is likely to exist passed on genetically to the next generation.

The objective of ownership a balderdash is to buy an animal that will enhance the genetics of his offspring. Selection based on a raw phenotypes such as bodily weights or ultrasound scan values places selection force per unit area not just on the genetic potential of an animal but also on environmental influences (herd, yr, flavor, management, etc.). If you look at two drastically different direction scenarios: 1) fodder tested  bulls, and 2) high concentrate fed bulls, it would be expected that the high concentrate bulls would have greater intramuscular fatty pct (Imf) figures. The question remains, are the more than desirable International monetary fund browse figures due to genetics or the fact that they received more than feed? We know that the environmental benefits will non be passed from parent to offspring, only the genetics. Consequently, selection based on EPDs volition help sort the wheat from the chaff in that EPDs eliminate environmental differences and quantify genetic differences.

EPD Definitions

	Bull A	Bull B
Calving ease direct	10	6
Nascency weight	ii.0	3.5
Weaning weight direct	20	22
Yearling weight	forty	52
Yearling height	0.three	0.6
Milk	3	-ii
Maternal weaning weight	13	9
Gestation length	-0.1	1.1
Calving ease maternal	4	half-dozen
Mature daughter height	0.v	i.0
Mature girl weight	0	30
Scrotal circumference	0.1	-0.45
Heifer pregnancy	6	9
Udder	0.iv	-0.i
Teat	0.5	0
Carcass weight	ii.0	twenty
Percent retail cuts	0	0.2
Marbling	0	-0.iii
International monetary fund	three.0	1.0
Rib-center expanse	0.06	ane.six
Fat thickness	-0.01	-0.09
Rump fat thickness	-0.03	-0.10
Tenderness	-0.01	0.one
Days to end	xv	ten
Balance average daily gain	-0.1	0.05
Residual feed intake	-0.05	0.x
Dry matter intake	0.2	0.four
Stayability	x	6
Maintenance free energy	0	10
Docility	vi	ii

Calving ease direct — Bull A should have iv percent more than unassisted births from first-calf heifers than Balderdash B. While birth weight is an indicator of calving ease, it does non tell the whole story. Calving ease is an economically relevant trait. Producers should not utilize both birth weight and calving ease EPDs together since the nativity weight EPD is already used in the calculation of calving ease.

Nascency weight — Bull B'southward calves would exist on average 1.5 pounds heavier at birth. Continue in mind that when crossing breeds, heterosis or hybrid vigor can increase nativity weights over a straightbred boilerplate.  When selecting bulls to use on heifers, the economically relevant trait is calving ease and producers should focus on calving ease EPD rather than birth weight EPD.

Weaning weight directly — Calves from Bull B should average 2 pounds more on adjusted weaning weights because of boosted growth. Because of the low accuracy associated with yearling bulls, the amount of emphasis placed on such a small-scale difference should be express. These EPDs are almost the same even if the accuracies were high.

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

Yearling height — Bull B'south calves should be 0.3 inches taller on average at a yr of age compared to the offspring of Bull A. Summit measurements are taken at the hip. Acme (the actual measurement and not the EPD), along with age, is used to calculate frame score.

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

Total maternal (maternal weaning weight) — Daughters from Balderdash A volition produce calves that are 4 pounds heavier at weaning on average considering of their combined genetics for growth and milk. This is a calculated figure of one-half the balderdash's weaning weight direct EPD plus his milk EPD. For example, Bull A has a maternal weaning weight value of 13, which is equal to one-half of his weaning weight direct EPD (20/2=10) plus his milk EPD (iii).

Gestation length — Calves from Bull A should have a one-day shorter gestation.

Calving ease maternal — Bull B's daughters should calve equally first-calf heifers with 2 percent more unassisted births (6-4) than the daughters of Bull A.

Mature summit — Bull B's daughters should be .5 inches taller at maturity.

Mature weight — Bull B'south daughters should be 30 pounds heavier when mature.

Scrotal circumference — Balderdash calves from Bull A should take 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 take daughters that reach puberty earlier.  It is also an indicator of the capacity for sperm production of a bull.

Heifer pregnancy — Daughters of Bull B are 3 pct more probable to get pregnant as heifers.

Udder score — Daughters of Balderdash A are expected to have 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 intermission (more than desirable).

Teat score — Daughters of Bull A are expected to accept teats that score 0.v 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 have 18 pounds more adjusted carcass weight.

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

Marbling — Calves from Bull A should have a 0.three college marbling score. Marbling scores range from 1.0, which is devoid of marbling and a utility quality form to 10.ix, which is abundant marbling and a prime number + quality course. For instance, if calves sired by Bull B had a marbling score of 5.0, and so we would look calves sired past Bull A to have a marbling score of 5.iii. Ultrasound EPDs were calculated for a number of breeds for traits of rib-eye area, fat, and intramuscular fatty (Imf), which is correlated to marbling, but now the majority of breeds use these ultrasound measurements in the adding of carcass EPDs. And then, instead of seeing both an International monetary fund EPD and a marbling EPD you but see the marbling EPD, but it has ultrasound measurements included in the calculation.

Imf — Calves from Bull A should produce calves with 2% more intramuscular fatty than calves sired by Bull B.  Intramuscular fat per centum (Imf) is measured by ultrasound and is a proxy for carcass marbling.  About breeds contain this measurement into their corresponding carcass marbling EPD every bit an indicator trait.

Rib-eye area — At a given end point, calves from Bull B should have rib-heart areas that are 1.54 square inches larger than Bull A'south calves.

Fat thickness — At a given end betoken,calves from Balderdash A should be 0.08 inches fatter when measured at the twelfth rib. This would exist less desirable on a carcass beast, but extremely lean females going back into a cowherd may also exist undesirable.

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

Tenderness — Calves sired by Bull A should produce meat that is more than tender than that of calves sired past Bull B by 0.2 pounds of shear force. Tenderness is measured by Warner Bratzler Shear Force (WBSF) that is reported in the pounds of forcefulness required to cut through a 1-inch thick piece of meat. A lower value is more desirable.

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

Residual average daily gain — Calves sired past Bull B should gain 0.15 pounds per twenty-four hours more than those sired by balderdash A when fed the same amount of feed during the post-weaning phase.

Residual feed intake — Calves sired by Bull A should consume 0.fifteen pounds less feed per solar day than those sired by balderdash B given the same levels of gain during the mail-weaning phase.  Note that selection based on balance average daily proceeds and balance feed intake may not pb to the same bull pick decisions.

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

Stayability — A measure of reproductive longevity. Daughters of Bull A are 4 percent more likely to stay productive in the herd to age half dozen.

Maintenance energy — The Scarlet Angus Association of America calculates a Maintenance Free energy (ME) Expected Progeny Difference (EPD) that indicates differences in the Mcal/month needed for maintenance due to mature size (corrected for trunk status score) and milking ability (The Rancher's Guide to EPDs is available at world wide web.redangus.org). A much simpler way to call up of information technology is that a balderdash with a ME EPD of +10 compared to one that is +0 will produce daughters that will require approximately 11 more pounds of average quality fodder permonth (assuming average quality forage = .86Mcal/lb).

Docility — Bull A should sire iv percent more than calves that have a temperament in the most docile score than Bull B. The actual measurement of docility is recorded either at weaning or yearling (depending on the breed association) and is categorized equally the animals' behavior as they enter, are restrained in, and exit the chute.

Beef Improvement Federation (BIF) temperament scoring organisation

1. Docile — Balmy disposition; gentle and easily handled. Stands and moves slowly during processing, undisturbed, settled, and somewhat boring and does non pull on the headgate when in the chute; exits the chute calmly.

2. Restless — Quieter than boilerplate but slightly restless, might be stubborn during processing, might try to dorsum from the chute, pulls back on the headgate, some tail flicking, exits the chute promptly.

3. Nervous — Typical temperament is manageable but nervous and impatient with a moderate amount of struggling, move, and tail flicking likewise 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 blare and froth at the oral fissure, continuous tail flicking, defecates and urinates during processing, aimlessly runs the fence line and might jump when penned individually, exhibits long flight distance, and exits the chute nervously.

5. Aggressive — Similar to Score 4 simply 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 lonely.

six. Very Aggressive — Extremely aggressive temperament. Thrashes well-nigh or attacks wildly when confined in small, tight places. Pronounced attack beliefs.

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Source: https://beef-cattle.extension.org/epd-basics-and-definitions/

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