AMGA EPD Descriptions
Calving Ease EPDs: Are based on calving difficulty scores, birth weights and gestation length information. More positive EPD’s are favorable and indicate easier calving. This means that a bull with +5 for calving ease is predicted to have 5% more of his calves born unassisted than a bull with a calving ease EPD of zero.
- CE % Dir (Direct Calving Ease) - The EPD for direct calving ease indicates the influence of the sire on calving ease if joined to purebred females calving at two years of age.
- CE % Daughters (Daughters Calving Ease) - The EPD for daughters' calving ease indicates how easily that sire's daughters will calve at two years of age.
Gestation Length (GL) (days) is an estimate of the time from conception to the birth of the calf and is based on AI records. Lower (negative) GL EPD’s indicate shorter gestation length and therefore easier calving.
Birth Weight EPD (BW) (lbs) is based on the measured birth weight of progeny, adjusted for the age of the dam. Progeny sired by a bull with a BW EPD of 2.2 can be expected to weigh 3.2 lb. more at birth, on average, than progeny sired by a bull with an EPD of -1.0 lb. (2.2 minus -1.0 = 3.2 lb.) Birth weight is a major factor influencing calving ease. Larger BW EPD’s usually, but not always, indicate more calving difficulty. The lower the value the lighter the calf at birth and the lower the likelihood of a difficult birth. This is particularly important when selecting sires for use over heifers.
Weaning Weight EPD (WW) (lbs) The WW EPD reflects pre-weaning growth potential. It is an indicator of direct genes for growth independent of milk production of the dam. Calves sired by a bull with a WW EPD of +30 should have a 20 lb. advantage in weaning weight compared to calves sired by a bull with an EPD of +10 lb. (30 minus 10.0 = 20 lb.). It is calculated from the weight of progeny taken between 80 and 300 days of age. Values are adjusted to 200 days. The dams age is also taken into consideration. This EPD is the best single estimate of an animal's genetic merit for growth to early ages.
Yearling Weight EPD (YW) (lbs) The yearling weight EPD is calculated from the weight of progeny taken between 301 and 500 days of age and adjusted to 400. The dams age is also taken into consideration. YW EPD for a sire with an EPD of +87 indicates that on average, his progeny should be 30 lbs. above the average of progeny of a bull with an EPD of +57 lbs as yearlings. This EPD is the best single estimate of an animal's genetic merit for yearling weight.
600-Day Weight EPD (lbs) is calculated from the weight of progeny taken between 501 and 900 days of age and adjusted to 600 days and for age of dam. This EPD is the best single estimate of an animal's genetic merit for growth beyond yearling age.
Mature Cow Weight EPD (MCW) (lbs) is based on the cow weight when the calf is weighed for weaning and adjusted to 5 years of age. This EPD is an estimate of the genetic difference in cow weight at 5 years of age and is an indicator of growth at later ages and potential feed maintenance requirements of the females in the breeding herd. Smaller, or more moderate EPD’s are generally more favorable. The Mature Cow Weight EPD may also be used by steer breeders wishing to grow animals out to a larger weight.
Milk EPD (lbs) is an estimate of an animal's milking ability. For sires, this EPD indicates the effect of the daughter's milking ability, inherited from the sire, on the 200 and 400 day weights of her calves. The higher the EPD for bulls the better his daughters are expected to milk. For dams, it indicates her own milking ability.
Scrotal Circumference EPD (SC) (cm) is calculated from the circumference of the scrotum, measured in centimeters and adjusted to 400 days of age. This EPD is an estimate of a sire's genetic merit for scrotal size, semen quality and quantity and is positively correlated to age of puberty in heifers and bulls progeny.
Days to Calving (days) - This EPD indicates the fertility of the daughters of the sire. It is the time interval between the date when the female is first exposed to a bull in a paddock mating, to the day when she subsequently calves. A negative EPD for days to calving indicates a shorter interval from bull-in date to calving and therefore higher fertility.
Carcass Weight EPD (CW) (lbs) is based on carcass records and is an indicator of the genetic differences in carcass weight at the standard age of 650 days.
Rib Eye Muscle Area EPD (REA) (sq inches) is calculated from measurements from live animal ultrasound scans on animals and from abattoir carcass data and are adjusted to a standard 660 lb carcass. This EPD estimates genetic differences in eye muscle area at the 12/13th rib site of a 660 lb dressed carcass. More positive EPD’s indicate better muscling on animals. Sires with relatively higher REA EPD’s are expected to produce better muscled and higher percentage yielding progeny at the same carcass weight than will sires with lower REA EPD’s.
Rib Fat and Rump Fat EPD (FAT) (inches) are calculated from measurements of subcutaneous fat depth at the 12/13 rib site and the P8 rump site respectively (from live animal ultrasound scans and from abattoir carcasses) and are adjusted to a standard 660 lb carcass. These EPD’s are indicators of the genetic differences in fat distribution on a standard 660 lb carcass. Sires with low, or negative, fat EPD’s are expected to produce leaner progeny in a 660 lb. carcass, than will sires with higher EPD’s. Rib fat is used in USDA yield grade calculation and is the most important determinant of retail yield. Higher amounts of rib fat decrease cutability and produce less desirable yield grades.
Intramuscular Fat EPD (IMF) (%) IMF EPD’s reflect genetic differences in the percentage of intramuscular fat at the 12/13th rib site in a 660 lb carcass based on ultrasound measurements of live yearling cattle and abattoir carcass information. Breeding cattle with higher IMF EPD’s should produce slaughter progeny with a higher degree of intramuscular fat and therefore higher quality grades.
Retail Beef Yield EPD (RBY) (%) indicates genetic differences between animals for retail yield percentage in a standard 660 lb carcass. Sires with larger EPD’s are expected to produce progeny with higher yielding carcasses.
Accuracy (Acc) (%) is based on the amount of performance information available on the animal and its close relatives - particularly the number of progeny analyzed. Accuracy is also based on the heritability of the trait and the genetic correlations with other recorded traits. Hence accuracy indicates the "confidence level" of the EPD. Accuracy ranges from 0-99% and indicates the probability of an EPD changing with the addition of more progeny data. The magnitude of possible change decreases as accuracy increases. Accuracy below 15% should be regarded as low, between 15%-35% as medium, between 35% and 55% as medium –high, and above 55% as high. |
