Negative Calving Ease Dairy Vs Beef
EPD Basics and Definitions
Matthew Spangler
University of Nebraska, Lincoln
mspangler2@unl.edu
*Click here for printable pdf version.
Summary:
EPDs represent the genetic component of an animate being'due south phenotype that is expected to exist passed on to the next generation. Studies have shown that using EPDs are seven to nine times more effective than selecting based on actual phenotypes. While most producers call up of increasing the economic efficiency of their performance 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 frequently disregarded. If option is based on nongenetic factors, as is the case when selecting on actual or adapted measurements instead of EPDs or economical indexes, then an inefficiency is automatically built into the cow/calf enterprise. It is critical to understand how to interpret EPDs and to know brood averages, and be able to use percentile ranks in lodge to identify potential sires that fit the desired breeding objective.
Introduction
Expected Progeny Differences (EPDs) permit for the comparing of animals within a breed for their genetic potential as parents for a given trait. EPDs have existed in the beef manufacture for decades and their use has produced intended genetic change in many traits. Withal, some producers are still reluctant to rely on EPDs when making selection decisions; presumably because of a full general lack of understanding of how EPDs are derived and their interpretation.
Basics of an EPD
Too frequently seedstock producers and balderdash buyers get caught upwardly in the actual weights, ultrasound data, etc., when selecting sires. EPDs provide a measure by which animals inside a breed can be compared to one another for their genetic potential equally parents for specific traits. EPDs incorporate multiple sources of information, including full full-blooded, an brute'southward own record, genomic information, and progeny information. As additional sources of data 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.
Full-blooded estimate:
| Sire EPD = 0.20 | Dam EPD = 0.10 |
| Progeny EPD = (0.20 + 0.x)/2 = 0.fifteen | |
Full-blooded estimate + creature tape:
EPD I = (0.v*EPD S ) + (0.five*EPD D ) + (0.5 *Mendelian Sampling Effect)
Where EPDI is the EPD for some individual I, EPDS is the EPD for the sire of animal I, EPDD 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 half of its alleles to its offspring and every allele has an equal likelihood of being passed on. This effect can be quantified using gimmicky grouping deviations and is a measure of how much ameliorate or worse an fauna is compared to the average of his parents. 1 could envision a scenario in which an fauna could receive only the about desirable alleles from both parents, resulting in a favorably big Mendelian sampling effect or the exact opposite, which could result in an unfavorably large sampling upshot. Perchance the best example is a set of flush mates. Although all of them have the same pedigree estimate, they differconsiderably in terms of performance and consequently their EPDs, once they have a record, differ due to Mendelian sampling. Current methodology behind the estimation of Mendelian sampling effects can be institute in the Beef Improvement Federation Guidelines at http://beefimprovement.org/content/uploads/2015/08/REVISED-MasterEd-BIF-GuidelinesFinal-08-2015.pdf.
When using EPDs, information technology is important to empathise 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.Due south. Meat Beast Enquiry Center (MARC) tin assist in determining differences betwixt EPDs of different breeds (Table I). These across breed adjustment factors, adapted to an Angus basis, are updated annually and can exist found at http://beefimprovement.org/library-2/convention-proceedings. There are beyond-breed genetic evaluations in existence (e.g., International Genetic Solutions; IGS) in beef cattle only producers should continue to utilise the USMARC derived adjustment factors if available to correctly adjust for brood furnishings.
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 animal is unknown. Below is a very simplistic equation describing the phenotype of an brute.
Where P is the phenotype, Thou is the genetic effect, and Eastward is the environmental effect.
The phenotype is what is seen, or measured, such as the actual scan data for REA or IMF. Both genetics and the surround influence these values, and because we are interested in identifyinganimals based on their potential as parents, the environment should not be included in the tool used to select animals. Furthermore, actual scan figures are not comparable from creature to animal since they have not been adapted nor practise they provide whatever clue equally to how much meliorate or worse an animal is compared to others. A contemporary group ratio does let for comparison of animals and provides an idea of how much better or worse a item animate being's adjusted record is compared to others inside the same contemporary group. The problem is that a ratio is not useful in comparing animals across herds or outside of the defined contemporary group.
The genetic and environmental components of phenotype tin can be further divided into condiment (A), dominance (D), and epistatic (I) genetic effects and both permanent (P) and temporary (T) environmental furnishings.
P = G A + Yard D + Grand I + Eastward P + E T
Generally speaking, we only become concerned with permanent environmental furnishings when we recollect near the ecology influence a dam has on her offspring (e.g., 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 condiment 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 caused by variation in additive values (σ2A). The heritability can be thought of as the average phenotypic differences or superiority that is likely to be passed on genetically to the next generation.
The objective of ownership a bull is to buy an creature that will enhance the genetics of his offspring. Option based on a raw phenotypes such as actual weights or ultrasound scan values places selection pressure level not only on the genetic potential of an animal but likewise on environmental influences (herd, year, flavour, direction, etc.). If you look at 2 drastically different management scenarios: 1) forage tested bulls, and 2) high concentrate fed bulls, information technology would exist expected that the high concentrate bulls would have greater intramuscular fat percent (IMF) figures. The question remains, are the more desirable Imf browse figures due to genetics or the fact that they received more feed? Nosotros know that the environmental benefits volition not exist passed from parent to offspring, only the genetics. Consequently, selection based on EPDs will 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 directly | ten | 6 |
| Birth weight | 2.0 | 3.5 |
| Weaning weight directly | 20 | 22 |
| Yearling weight | 40 | 52 |
| Yearling acme | 0.3 | 0.6 |
| Milk | 3 | -two |
| Maternal weaning weight | 13 | 9 |
| Gestation length | -0.1 | 1.ane |
| Calving ease maternal | 4 | vi |
| Mature girl meridian | 0.five | one.0 |
| Mature girl weight | 0 | 30 |
| Scrotal circumference | 0.1 | -0.45 |
| Heifer pregnancy | half-dozen | 9 |
| Udder | 0.four | -0.1 |
| Teat | 0.5 | 0 |
| Carcass weight | 2.0 | 20 |
| Percentage retail cuts | 0 | 0.2 |
| Marbling | 0 | -0.3 |
| IMF | three.0 | ane.0 |
| Rib-heart area | 0.06 | 1.6 |
| Fatty thickness | -0.01 | -0.09 |
| Rump fat thickness | -0.03 | -0.10 |
| Tenderness | -0.01 | 0.i |
| Days to finish | 15 | 10 |
| Remainder boilerplate daily gain | -0.one | 0.05 |
| Residual feed intake | -0.05 | 0.10 |
| Dry affair intake | 0.2 | 0.four |
| Stayability | 10 | 6 |
| Maintenance energy | 0 | 10 |
| Docility | 6 | 2 |
Calving ease direct — Bull A should have four pct more unassisted births from first-calf heifers than Balderdash 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 utilise both birth weight and calving ease EPDs together since the birth weight EPD is already used in the calculation of calving ease.
Nascence weight — Bull B'due south calves would exist on average one.five pounds heavier at birth. Keep in listen that when crossing breeds, heterosis or hybrid vigor tin increase birth 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 nativity weight EPD.
Weaning weight direct — Calves from Bull B should average 2 pounds more than on adjusted weaning weights because of boosted growth. Because of the low accurateness associated with yearling bulls, the amount of emphasis placed on such a minor difference should be limited. These EPDs are virtually the same even if the accuracies were high.
Yearling weight — Bull B's calves should average 12 pounds heavier at 1 twelvemonth of historic period.
Yearling height — Bull B'south calves should exist 0.iii inches taller on average at a twelvemonth of historic period compared to the offspring of Bull A. Height measurements are taken at the hip. Acme (the bodily 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 departure between +three and -ii) heavier at weaning. This is not a measure of pounds of milk merely rather weaning weight due to milk production. This v pounds, different the weaning weight figure attributed to growth from the bull, is the result of differences in the daughters' milk production and mothering power. 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 Bull A will produce calves that are four pounds heavier at weaning on average considering of their combined genetics for growth and milk. This is a calculated figure of one-half the bull'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 half of his weaning weight directly EPD (20/2=10) plus his milk EPD (iii).
Gestation length — Calves from Bull A should have a ane-twenty-four hours shorter gestation.
Calving ease maternal — Balderdash B'south daughters should calve as commencement-calf heifers with 2 pct more than unassisted births (six-iv) than the daughters of Bull A.
Mature meridian — Balderdash B's daughters should be .five inches taller at maturity.
Mature weight — Balderdash B's daughters should be 30 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 historic period of maturity of a bull'due south daughters. Bulls with larger scrotal circumference should take daughters that reach puberty earlier. Information technology is likewise an indicator of the capacity for sperm production of a bull.
Heifer pregnancy — Daughters of Balderdash B are three percent more likely to get meaning every bit heifers.
Udder score — Daughters of Bull A are expected to have udders that score 0.five points higher on average compared to daughters of Bull B. A higher udder score is indicative of a tighter udder intermission (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 have 18 pounds more than adjusted carcass weight.
Per centum retail production — The calves from Balderdash B should yield 0.two percent more than closely trimmed, boneless retail cuts from the round, loin, rib, and chuck. Some breeds may written report a Yield Grade (YG) EPD. The aforementioned factors (back fatty, ribeye expanse, and carcass weight) would exist included, but a lower YG is more than desirable equally opposed to per centum retail product where a higher value is more desirable. In either percent retail product or YG, fat thickness contributes the about to these 2 calculations. Consequently, selecting for decreased YG or increased percentage retail product will lead to bacteria animals so caution should be used to avert extremely lean replacement females.
Marbling — Calves from Bull A should take a 0.3 college marbling score. Marbling scores range from 1.0, which is devoid of marbling and a utility quality class to x.ix, which is abundant marbling and a prime number + quality grade. For example, if calves sired by Balderdash B had a marbling score of 5.0, then nosotros would expect calves sired by Balderdash A to accept a marbling score of v.three. Ultrasound EPDs were calculated for a number of breeds for traits of rib-centre area, fat, and intramuscular fat (International monetary fund), which is correlated to marbling, but now the majority of breeds employ these ultrasound measurements in the calculation of carcass EPDs. So, instead of seeing both an IMF EPD and a marbling EPD y'all merely see the marbling EPD, but information technology 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 fatty percentage (Imf) is measured by ultrasound and is a proxy for carcass marbling. Most breeds incorporate this measurement into their corresponding carcass marbling EPD equally an indicator trait.
Rib-centre surface area — At a given cease signal, calves from Bull B should take rib-centre areas that are 1.54 foursquare inches larger than Bull A's calves.
Fat thickness — At a given end point,calves from Bull A should exist 0.08 inches fatter when measured at the 12th rib. This would be less desirable on a carcass creature, but extremely lean females going back into a cowherd may likewise be undesirable.
Rump fat thickness — At a given end point, calves from Bull A should be 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 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 cut through a 1-inch thick piece of meat. A lower value is more than desirable.
Days to finish — Calves sired by Bull B should spend five 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 24-hour interval more than those sired by balderdash A when fed the same amount of feed during the post-weaning phase.
Residual feed intake — Calves sired past Bull A should consume 0.15 pounds less feed per day than those sired by balderdash B given the same levels of proceeds during the post-weaning phase. Note that selection based on residual boilerplate daily gain and residual feed intake may not lead to the aforementioned bull selection decisions.
Dry matter intake — Calves sired by Bull B are expected to consume 0.2 pounds more feed per day on a dry matter basis compared to those sired past Bull A.
Stayability — A measure of reproductive longevity. Daughters of Bull A are iv percent more than likely to stay productive in the herd to age half-dozen.
Maintenance energy — The Crimson Angus Association of America calculates a Maintenance Energy (ME) Expected Progeny Difference (EPD) that indicates differences in the Mcal/calendar month needed for maintenance due to mature size (corrected for trunk condition score) and milking power (The Rancher's Guide to EPDs is available at www.redangus.org). A much simpler fashion to think of it is that a bull with a ME EPD of +x compared to 1 that is +0 will produce daughters that will require approximately xi more pounds of average quality provender percalendar month (assuming average quality forage = .86Mcal/lb).
Docility — Balderdash A should sire 4 pct more than calves that have a temperament in the near docile score than Balderdash B. The actual measurement of docility is recorded either at weaning or yearling (depending on the breed association) and is categorized as the animals' beliefs as they enter, are restrained in, and exit the chute.
Beef Improvement Federation (BIF) temperament scoring system |
| 1. Docile — Mild disposition; gentle and easily handled. Stands and moves slowly during processing, undisturbed, settled, and somewhat dull and does not pull on the headgate when in the chute; exits the chute calmly. |
| 2. Restless — Quieter than average merely slightly restless, might be stubborn during processing, might endeavor to back 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, movement, and tail flicking as well equally 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 oral fissure, continuous tail flicking, defecates and urinates during processing, frantically runs the fence line and might jump when penned individually, exhibits long flight altitude, and exits the chute nervously. |
| 5. Aggressive — Similar to Score four just with added aggressive beliefs, fearful, extreme agitation, continuous move that might include jumping and bellowing while in the chute, exits the chute frantically and might exhibit attack behavior when handled alone. |
| vi. Very Aggressive — Extremely aggressive temperament. Thrashes about or attacks wildly when bars in modest, tight places. Pronounced assail behavior. |
*Click here for printable pdf version.
Source: https://beef-cattle.extension.org/epd-basics-and-definitions/
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