Expected Progeny Difference
Encyclopedia
Expected progeny differences (EPD) are an evaluation of an animal
’s genetic worth as a parent. They are based on animal model
s which combine all information known about an individual and its relatives to create a genetic profile of the animal’s merits. These profiles are then compared only to other individuals of the same breed.
. Each set of letters stands for a specific measurement with an accuracy reading and percent rank below it. Each EPD is compared to the breed
average
of a given year. The number given by the EPD is the amount above or below this given average.
.
Calving
ease predicts the level of difficulty first time heifer
s will have during birth. These are determined by the percentage of unassisted births for that particular animal.
Birth weight
measures how much above or below the breed’s average an offspring
will gain due to the parent. It does not necessarily predict the exact weight of all offspring, but instead gives a general prediction of how much extra or less weight an offspring will weigh compared to if it had been sired by another bull. High birth weight is the biggest cause of difficulty in calving, so having a bull
with a low birth weight EPD is high beneficial.
Weaning
and yearling
weight measure the amount of weight an offspring has gained by the time it is weaned and at the one year mark. Typically the weaning weight is measured at the 205 day mark and the yearling weight is taken at the 365 day mark. Typically a larger number is favored for both of these traits.
Milk EPDs give an estimate for the maternal portion of the weaning weight that determined by milk production of the dam
. It is measured in pounds of weaning weight of a bull’s grandprogeny due to the milk production of the bull’s daughters.
circumference is an indicator of a bull’s fertility
. A larger circumference is preferred and is an indicator for his sons to have a larger scrotal circumference and his daughters to reach puberty
sooner and therefore have calves
sooner.
Gestation
length is an indicator of the probability of dystocia
. The longer a calf is in utero
the larger it will be at birth and the greater the chance of it having dystocia. It also gives the cow a larger postpartum interval between pregnancies
. A shorter gestation length is usually preferred because of this.
Stayability is an indicator EPD of longevity
of a bull’s daughter in a cow herd. The higher the EPD value the greater chance a cow will stay in a herd over six years and continue producing quality offspring.
predicts what an animal’s total retail
product will be compared to other animals of that breed. It does not however predict percent retail value, or the actual amount of sellable meat
that can be produced from the carcass.
Fat
thickness determined the expected external and seam fat the animal will contain. These two factors contribute to the greatest waste in an animal and best way to reduce economic loss. Fat thickness EPDs can help producers reduce this loss, by using animals with mid range EPDs, so as not to have too little or too much fat.
Marbling
EPDs are also important in the beef
industry for predicting palatability in a beef carcass. They show the estimated USDA Quality grading System and marbling score an animal would receive if it were slaughtered
. This EDP is different in that it is measured in units of marbling score, and not in weight gained by an animal. Higher values indicate the presence of genes that will produce more intramuscular fat
.
usage. Through mathematical equations and computing power EPDs can be generated for use in both situations. Through EPDs certain phenotype
s can be chosen for over others. Use of EPSs and DNA markers can help when choosing certain traits over others. By using certain EPDs of an animal one can rapidly improve genetics of a herd, especially for highly heritable traits such as marbling. In addition, by using a combination of EPDs and DNA markers, EPDs can be made more accurate. When new DNA markers are used, they can help adjust the EPD according to the genotype
and therefore produce a more accurate measurement.
To determine how accurate EPDs are for an individual, samples of all of a bull’s offspring are looked at and compared to what their expected outcome should have been. The EPDs can then be changed based on the values that are gathered. The higher the accuracy rate, the closer most of the progeny
will be to the EPD values listed. Accuracy is not an indicator of beneficial EPDs, but rather shows how close the EPD is to the true genetic potential of the animal. The closer an accuracy value is to 1, the more accurate the EPDs can be thought to be. Other factors can affect the progeny as well, such as non genetic effects including feed, weather, environment, as well as random Mendelian sampling
.
In addition to the EPD and accuracy shown in a chart, often the percent rank is also given. This shows what percentile the animal ranks for the given EPD. The higher the percentile
, the better the EPD is for that characteristic. The better the EPDs for a given bull, the higher chance its progeny will have a given characteristic.
Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...
’s genetic worth as a parent. They are based on animal model
Animal model
An animal model is a living, non-human animal used during the research and investigation of human disease, for the purpose of better understanding the disease without the added risk of causing harm to an actual human being during the process...
s which combine all information known about an individual and its relatives to create a genetic profile of the animal’s merits. These profiles are then compared only to other individuals of the same breed.
Types of EPD’s
An example of a set of EPDs looks like the following chartChart
A chart is a graphical representation of data, in which "the data is represented by symbols, such as bars in a bar chart, lines in a line chart, or slices in a pie chart"...
. Each set of letters stands for a specific measurement with an accuracy reading and percent rank below it. Each EPD is compared to the breed
Breed
A breed is a group of domestic animals or plants with a homogeneous appearance, behavior, and other characteristics that distinguish it from other animals or plants of the same species. Despite the centrality of the idea of "breeds" to animal husbandry, there is no scientifically accepted...
average
Average
In mathematics, an average, or central tendency of a data set is a measure of the "middle" value of the data set. Average is one form of central tendency. Not all central tendencies should be considered definitions of average....
of a given year. The number given by the EPD is the amount above or below this given average.
| CE | BW | WW | YW | MCE | Milk | MWW | Stay | CW | YG | Marb | Fat | REA | API | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| EPD | 8 | 1.8 | 44.5 | 84.3 | 4.4 | 3.4 | 25.6 | 18.2 | 15.4 | .09 | .02 | .00 | -.05 | 104.4 |
| Acc | .32 | .75 | .72 | .68 | .18 | .31 | .32 | .11 | .52 | .33 | .32 | .43 | .29 | |
| %Rank | 10 | 3 | 15 | 4 | 20 |
Growth EPDs
Growth EPDs measure the amount of weight a given offspring will gain due to the parent’s geneticsGenetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
.
Calving
Calving
Calving may refer to:*Calving, the process of giving birth to a calf*Ice calving, the process by which an iceberg breaks off from an ice shelf or glacier...
ease predicts the level of difficulty first time heifer
Heifer
Heifer may refer to:*A young cow before she has had her first calf*Red Heifer, in Judaism is a heifer that is sacrificed and whose ashes are used for the ritual purification*Heifer International, a charitable organization...
s will have during birth. These are determined by the percentage of unassisted births for that particular animal.
Birth weight
Birth weight
Birth weight is the body weight of a baby at its birth.There have been numerous studies that have attempted, with varying degrees of success, to show links between birth weight and later-life conditions, including diabetes, obesity, tobacco smoking and intelligence.-Determinants:There are...
measures how much above or below the breed’s average an offspring
Offspring
In biology, offspring is the product of reproduction, of a new organism produced by one or more parents.Collective offspring may be known as a brood or progeny in a more general way...
will gain due to the parent. It does not necessarily predict the exact weight of all offspring, but instead gives a general prediction of how much extra or less weight an offspring will weigh compared to if it had been sired by another bull. High birth weight is the biggest cause of difficulty in calving, so having a bull
Bull
Bull usually refers to an uncastrated adult male bovine.Bull may also refer to:-Entertainment:* Bull , an original show on the TNT Network* "Bull" , an episode of television series CSI: Crime Scene Investigation...
with a low birth weight EPD is high beneficial.
Weaning
Weaning
Weaning is the process of gradually introducing a mammal infant, either human or animal, to what will be its adult diet and withdrawing the supply of its mother's milk.The process takes place only in mammals, as only mammals produce milk...
and yearling
Yearling
Yearling may refer to:*Yearling , an animal in its second year of life.**Yearling , a horse between one and two years of age.in titles or proper names:*Yearling Books, an imprint of the publishing company Random House....
weight measure the amount of weight an offspring has gained by the time it is weaned and at the one year mark. Typically the weaning weight is measured at the 205 day mark and the yearling weight is taken at the 365 day mark. Typically a larger number is favored for both of these traits.
Milk EPDs give an estimate for the maternal portion of the weaning weight that determined by milk production of the dam
Mother
A mother, mum, mom, momma, or mama is a woman who has raised a child, given birth to a child, and/or supplied the ovum that grew into a child. Because of the complexity and differences of a mother's social, cultural, and religious definitions and roles, it is challenging to specify a universally...
. It is measured in pounds of weaning weight of a bull’s grandprogeny due to the milk production of the bull’s daughters.
Reproductive EPDs
ScrotalScrotum
In some male mammals the scrotum is a dual-chambered protuberance of skin and muscle containing the testicles and divided by a septum. It is an extension of the perineum, and is located between the penis and anus. In humans and some other mammals, the base of the scrotum becomes covered with curly...
circumference is an indicator of a bull’s fertility
Fertility
Fertility is the natural capability of producing offsprings. As a measure, "fertility rate" is the number of children born per couple, person or population. Fertility differs from fecundity, which is defined as the potential for reproduction...
. A larger circumference is preferred and is an indicator for his sons to have a larger scrotal circumference and his daughters to reach puberty
Puberty
Puberty is the process of physical changes by which a child's body matures into an adult body capable of reproduction, as initiated by hormonal signals from the brain to the gonads; the ovaries in a girl, the testes in a boy...
sooner and therefore have calves
Calf
Calves are the young of domestic cattle. Calves are reared to become adult cattle, or are slaughtered for their meat, called veal.-Terminology:...
sooner.
Gestation
Gestation
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....
length is an indicator of the probability of dystocia
Dystocia
Dystocia is an abnormal or difficult childbirth or labour. Approximately one fifth of human labours have dystocia.Dystocia may arise due to incoordinate uterine activity, abnormal fetal lie or presentation, absolute or relative cephalopelvic disproportion, or a massive fetal tumor such as a...
. The longer a calf is in utero
In utero
In utero is a Latin term literally meaning "in the womb". In biology, the phrase describes the state of an embryo or fetus. In legal contexts, the phrase is used to refer to unborn children. Under common law, unborn children are still considered to exist for property transfer purposes.-See also:*...
the larger it will be at birth and the greater the chance of it having dystocia. It also gives the cow a larger postpartum interval between pregnancies
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
. A shorter gestation length is usually preferred because of this.
Stayability is an indicator EPD of longevity
Longevity
The word "longevity" is sometimes used as a synonym for "life expectancy" in demography or known as "long life", especially when it concerns someone or something lasting longer than expected ....
of a bull’s daughter in a cow herd. The higher the EPD value the greater chance a cow will stay in a herd over six years and continue producing quality offspring.
Carcass EPDs
Carcass weightCarcass weight
Carcass weight refers to the weight of an animal after slaughter and removal of most internal organs, head, and skin. On average the carcass weight of beef is about 60% of the live animal weight, for hogs it is about 73%....
predicts what an animal’s total retail
Retail
Retail consists of the sale of physical goods or merchandise from a fixed location, such as a department store, boutique or kiosk, or by mail, in small or individual lots for direct consumption by the purchaser. Retailing may include subordinated services, such as delivery. Purchasers may be...
product will be compared to other animals of that breed. It does not however predict percent retail value, or the actual amount of sellable meat
Meat
Meat is animal flesh that is used as food. Most often, this means the skeletal muscle and associated fat and other tissues, but it may also describe other edible tissues such as organs and offal...
that can be produced from the carcass.
Fat
Fat
Fats consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. Chemically, fats are triglycerides, triesters of glycerol and any of several fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure...
thickness determined the expected external and seam fat the animal will contain. These two factors contribute to the greatest waste in an animal and best way to reduce economic loss. Fat thickness EPDs can help producers reduce this loss, by using animals with mid range EPDs, so as not to have too little or too much fat.
Marbling
Marbling
Marbling may refer to:*The quality of a surface that has streaks of color, like marble. For example:**Marbleizing, also called faux marbling, the art of painting walls or furniture to look like real marble....
EPDs are also important in the beef
Beef
Beef is the culinary name for meat from bovines, especially domestic cattle. Beef can be harvested from cows, bulls, heifers or steers. It is one of the principal meats used in the cuisine of the Middle East , Australia, Argentina, Brazil, Europe and the United States, and is also important in...
industry for predicting palatability in a beef carcass. They show the estimated USDA Quality grading System and marbling score an animal would receive if it were slaughtered
Animal slaughter
Slaughter is the term used to describe the killing and butchering of animals, usually for food. Commonly it refers to killing and butchering of domestic livestock ....
. This EDP is different in that it is measured in units of marbling score, and not in weight gained by an animal. Higher values indicate the presence of genes that will produce more intramuscular fat
Intramuscular fat
Intramuscular fat or Intramuscular triglycerides is located throughout skeletal muscle and is responsible for the marbling seen in certain cuts of beef. In humans, excess accumulation of intramuscular fat is associated with insulin resistance and type 2 diabetes...
.
Use and Accuracy
EPDs are used in both scientific research and in typical farmFarm
A farm is an area of land, or, for aquaculture, lake, river or sea, including various structures, devoted primarily to the practice of producing and managing food , fibres and, increasingly, fuel. It is the basic production facility in food production. Farms may be owned and operated by a single...
usage. Through mathematical equations and computing power EPDs can be generated for use in both situations. Through EPDs certain phenotype
Phenotype
A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
s can be chosen for over others. Use of EPSs and DNA markers can help when choosing certain traits over others. By using certain EPDs of an animal one can rapidly improve genetics of a herd, especially for highly heritable traits such as marbling. In addition, by using a combination of EPDs and DNA markers, EPDs can be made more accurate. When new DNA markers are used, they can help adjust the EPD according to the genotype
Genotype
The genotype is the genetic makeup of a cell, an organism, or an individual usually with reference to a specific character under consideration...
and therefore produce a more accurate measurement.
To determine how accurate EPDs are for an individual, samples of all of a bull’s offspring are looked at and compared to what their expected outcome should have been. The EPDs can then be changed based on the values that are gathered. The higher the accuracy rate, the closer most of the progeny
Progeny
Progeny can refer to:*A genetic descendant or offspring*An academic progeny Other uses*Progeny Linux Systems*Progeny - an episode of the television series Stargate Atlantis...
will be to the EPD values listed. Accuracy is not an indicator of beneficial EPDs, but rather shows how close the EPD is to the true genetic potential of the animal. The closer an accuracy value is to 1, the more accurate the EPDs can be thought to be. Other factors can affect the progeny as well, such as non genetic effects including feed, weather, environment, as well as random Mendelian sampling
Mendelian randomization
In epidemiology, Mendelian randomization is a method of using measured variation in genes of known function to examine the causal effect of a modifiable exposure on disease in non-experimental studies...
.
In addition to the EPD and accuracy shown in a chart, often the percent rank is also given. This shows what percentile the animal ranks for the given EPD. The higher the percentile
Percentile
In statistics, a percentile is the value of a variable below which a certain percent of observations fall. For example, the 20th percentile is the value below which 20 percent of the observations may be found...
, the better the EPD is for that characteristic. The better the EPDs for a given bull, the higher chance its progeny will have a given characteristic.