Expected progeny difference EPDs, or expected progeny differences, are the
estimates of how future offspring of an animal are expected to perform relative to the offspring of other animals in the same breed, on average. By testing the genetics of a parent animal, predictions
can be made about the performance of that animal’s progeny, if the parent is bred to an animal of equal genetic value. You are measuring how that animal’s progeny are expected to perform. Keep in mind that EPDs are not a guarantee, but a very accurate estima- tion based on the genetic test results of a wide selection of animals in the same breed. EPDs can be used as a type of scorecard for genetic
traits that could help you decide between similar ani- mals. By comparing traits of the offspring of bulls bred to the same set of cows, the choice becomes less of a guessing game when put to numbers. For example, if
Abbreviations
Please refer to your breed of choice to see what EPDs are available and what specifi c traits are important to that breed. The number of traits and qualities vary by breed. Below are a sample of commonly used values and abbreviations.
Accuracy (Acc) The reliability that can be placed on the EPD, usually expressed in numbers or percent- ages.
Birth Weight (BW) Birth Weight EPDs are reported in pounds and predict the average difference that can be expected in an animal’s off- spring when compared with the offspring of a similar animal. This trait can be important to producers who would like to have calves with smaller birth weights, which can af- fect birthing ease.
Weaning Weight (WW) Wean-
ing Weight EPDs are expressed in pounds and predict the average differences in weight that can be expected between the progeny of animals in the same genetic evalu- ation at 205 days of age. Weaning Weight EPDs do not account for dif- ferences in weaning weight that are due to milk. Some weaning weight EPDs differentiate between direct and maternal traits.
Yearling Weight (YW) Yearling
weight EPDs are expressed in pounds while height is measured in inches. Predicts the average dif- ferences that can be expected be- tween the progeny of animals at one year of age.
Milk Expressed as pounds of calf weaned by a bull’s daughters, so this does not necessarily refl ect actual milking ability. This measures the av- erage differences in weaning weight that can be expected in progeny due to the milking ability of a bull’s daughters.
Yearling Height (YH) Reported in
inches to predict the average differ- ence in progeny hip height that can be expected at one year of age.
Calving Ease (CE Direct or Maternal) The average difference in ease with which a sire’s calves will be born when bred to fi rst-calf heifers (Di- rect) or when a sire’s daughters are bred as fi rst-calf heifers (Maternal). Expressed as a percentage of unas- sisted births, with a higher value in- dicating greater calving ease.
98 The Cattleman March 2016
Scrotal Circumference (SC) Esti- mates the average differences that can be expected in scrotal circum- ference in male progeny. Larger scrotal circumferences can have correlation to fertility. Measured in centimeters.
Mature Daughter Height and Weight (MDH, MDW) Predicts the average differences that can be expected in mature daughter size in inches and pounds,
respectively. These EPDs
can be used to match mature cow size to forage resources.
Carcass Weight (CW) Estimates the average differences in carcass weight. Expressed in pounds at a given age endpoint.
Marbling Predicts the average dif- ference in USDA marbling grade or quality in an animal’s progeny when compared to the progeny of another animal at a given age endpoint. Ex- pressed in numerical marbling score where one point equals one USDA marbling score.
you need a bull that will give you calves with heavier weaning weights, look for an individual with a higher weaning weight numerical value. EPDs can be a valu- able tool to improve on your herd’s strengths.
Categories and values Not all EPD values may be important to you or your
operation. Some breed associations only track certain values and traits, while others offer a wide variety. What categories of EPDs you will be interested in may depend on your type of operation. Are you looking to improve maternal traits such as
calving ease and milk production? Do you want to wean heavier calves or improve their carcass marbling? The values you are looking for will depend on what area of your operation you plan to change. Three general groups of traits that EPDs are used to measure are production, maternal and carcass. MORE
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