Understanding EBVs
The TransTasman Angus Cattle Evaluation is the genetic evaluation program adopted by Angus Australia for Angus and Angus influenced beef cattle. The TransTasman Angus Cattle Evaluation uses Best Linear Unbiased Prediction (BLUP) technology to produce Estimated Breeding Values (EBVs) of recorded cattle for a range of important production traits (e.g. weight, carcase, fertility).
The TransTasman Angus Cattle Evaluation is an international genetic evaluation and includes pedigree, performance and genomic information from the Angus Australia and Angus New Zealand databases, along with selected information from the American and Canadian Angus Associations.
What is an EBV?
An animal’s breeding value can be defined as its genetic merit for each trait. While it is not possible to determine an animal’s true breeding value, it is possible to estimate it. These estimates of an animal’s true breeding value are called EBVs (Estimated Breeding Values).
TACE EBVs are expressed as the difference between an individual animal’s genetics and a historical genetic level (i.e. group of animals) within the TransTasman Angus Cattle Evaluation, and are reported in the units in which the measurements are taken.
EBVs are calculated for a range of traits within TACE, covering calving ease, growth, fertility, maternal performance, carcase merit, feed efficiency, temperament and structural soundness.
Considering Accuracy
An accuracy value is published in association with each EBV, which is usually displayed as a percentage value immediately below the EBV.
The accuracy value provides an indication of the reliability of the EBV in estimating the animal’s genetics (or true breeding value), and is an indication of the amount of information that has been used in the calculation of the EBV.
TACE EBVs with accuracy values below 50% should be considered as preliminary or of low accuracy, 50-74% as of medium accuracy, 75-90% of medium to high accuracy, and 90% or greater as high accuracy.
Calving Ease Direct
Calving Ease Direct EBVs are estimates of genetic differences in the ability of a sire’s calves to be born unassisted from 2 year old heifers.
Calving Ease Direct EBVs are calculated from calving difficulty scores, birth weights, gestation length records and/or genomic information, and are expressed as differences in the percentage of calves that will be born unassisted.
Higher Calving Ease Direct EBVs indicate an animal is expected to produce fewer calving difficulties in 2 year old heifers (i.e. greater calving ease).
Calving Ease Daughters
Calving Ease Daughters EBVs are estimates of genetic differences in the ability of a sire’s daughters to calve unassisted at 2 years of age.
Calving Ease Daughters EBVs are calculated from calving difficulty scores, birth weights, gestation length records and/or genomic information, and are expressed as differences in the percentage of daughters that will calve unassisted.
Higher Calving Ease Daughters EBVs indicate an animal is expected to produce a higher percentage of daughters who will calve unassisted at 2 years of age.
Gestation Length
Gestation Length EBVs are estimates of genetic differences between animals in the length of time from the date of conception to the birth of the calf.
Gestation Length EBVs are calculated from the joining date and date of birth records for calves conceived by either artificial insemination (AI) or hand mating, and/or genomic information, and are expressed in day units.
Lower Gestation Length EBVs indicate an animal is expected to produce calves that are born with a shorter gestation length.
Birth Weight
Birth Weight EBVs are estimates of genetic differences between animals in calf weight at birth.
Birth Weight EBVs are calculated from the weight of animals at birth and/or genomic information, and are expressed in kilogram units.
Lower Birth Weight EBVs indicate the animal is expected to produce progeny with lighter birth weight.
200 Day Growth
200 Day Growth EBVs are estimates of genetic differences between animals in live weight at 200 days of age due to genetics for growth.
200 Day Growth EBVs are calculated from the live weight performance of animals when they are between 80 and 300 days of age, and/or genomic information, and are expressed in kilogram units.
Higher 200 Day Growth EBVs indicate the animal is expected to produce progeny with heavier live weights at 200 days of age.
400 Day Weight
400 Day Weight EBVs are estimates of genetic differences between animals in live weight at 400 days of age.
400 Day Weight EBVs are calculated from the live weight performance of animals when they are between 301 and 500 days of age, and/or genomic information, and are expressed in kilogram units.
Higher 400 Day Weight EBVs indicate the animal is expected to produce progeny with heavier live weights at 400 days of age.
600 Day Weight
600 Day Weight EBVs are estimates of genetic differences between animals in live weight at 600 days of age.
600 Day Weight EBVs are calculated from the live weight performance of animals when they are between 501 and 900 days of age, and/or genomic information, and are expressed in kilogram units.
Higher 600 Day Weight EBVs indicate the animal is expected to produce progeny with heavier live weights at 600 days of age.
Mature Cow Weight
Mature Cow Weight EBVs are estimates of genetic differences between animals in live weight of cows at 5 years of age.
Mature Cow Weight EBVs are calculated from the live weights of cows when their calves are 200 days of age (i.e. at or around weaning), and/or genomic information, and are expressed in kilogram units.
Higher Mature Cow Weight EBVs indicate the animal is expected to produce daughters with heavier mature weights. Heavier mature weights are associated with higher feed and maintenance costs, but conversely higher returns for cull cows.
Milk
Milk EBVs are estimates of genetic differences between animals in live weight at 200 days of age due to the maternal contribution of its dam.
Milk EBVs are calculated from the live weights of calves at 200 days of age (i.e. at or around weaning), and/or genomic information, and are expressed in kilogram units.
Higher Milk EBVs indicate the animal is expected to produce daughters that have heavier calves at 200 days of age due to superior maternal attributes (e.g. more milk).
Days to Calving
Days to Calving EBVs are estimates of genetic differences between animals in the time from the start of the joining period (i.e. when the female is introduced to a bull) until subsequent calving.
Days to Calving EBVs are calculated from the joining records submitted for both heifers and cows who have been mated naturally in a paddock situation, and are expressed in day units.
Lower Days to Calving EBVs indicate an animal is expected to produce progeny that conceive earlier in the joining period. Females with lower Days to Calving EBVs also tend to show earlier puberty as heifers and earlier return to oestrous after calving.
Scrotal Size
Scrotal Size EBVs are estimates of genetic differences between animals in scrotal circumference at 400 days of age.
Scrotal Size EBVs are calculated from scrotal circumference measurements of bulls that are between 300 and 700 days of age, and/or genomic information, and are expressed in centimetre units.
Higher Scrotal Size EBVs indicate the animal is expected to produce sons with larger scrotal circumference as yearlings and daughters that reach puberty earlier.
Carcase Weight
Carcase Weight EBVs are estimates of genetic differences between animals in hot standard carcase weight at 750 days of age.
Carcase Weight EBVs are calculated from the hot standard carcase weight of animals between 300 and 1000 days of age, and/or genomic information, and are expressed in kilogram units.
Higher Carcase Weight EBVs indicate the animal is expected to produce progeny with heavier carcase weights.
Eye Muscle Area
Eye Muscle Area (EMA) EBVs are estimates of genetic differences between animals in eye muscle area at the 12/13th rib site in a 400 kg carcase.
EMA EBVs are calculated by measuring the area of the cross section of the longissimus dorsi muscle between the 12 and 13th rib via either live animal ultrasound scanning or direct measurement of carcases in the abattoir, and/or genomic information. EMA EBVs are expressed in square centimetre units.
Higher EMA EBVs indicate the animal is expected to produce progeny with larger eye muscle area, relative to carcase weight.
Rib Fat
Rib Fat EBVs are estimates of genetic differences between animals in fat depth at the 12/13th rib site in a 400 kg carcase.
Rib Fat EBVs are calculated by measuring the fat depth at the 12/13th rib site via either live animal ultrasound scanning or direct measurement of carcases in the abattoir, and/or genomic information. Rib Fat EBVs are expressed in millimetre units.
Higher Rib Fat EBVs indicate the animal is expected to produce progeny with greater fat depth in a 400 kg carcase.
Rump Fat
Rump Fat EBVs are estimates of genetic differences between animals in fat depth at the P8 rump site in a 400 kg carcase.
Rump Fat EBVs are calculated by measuring the fat depth at the P8 rump site (located at the intersection of the line from the high bone with a line from the inside of the pin bone) via either live animal ultrasound scanning or direct measurement of carcases in the abattoir, and/or genomic information. Rump Fat EBVs are expressed in millimetre units.
Higher Rump Fat EBVs indicate the animal is expected to produce progeny with greater fat depth in a 400 kg carcase.
Retail Beef Yeild
Retail Beef Yield (RBY) EBVs are estimates of genetic differences between animals in boned out saleable meat from a 400 kg carcase.
RBY EBVs are calculated by measuring the boned out saleable meat of carcases in the abattoir, or from known relationships between saleable meat yield and other carcase measurements (e.g. fat depth). RBY EBVs are expressed in percentage units.
Higher RBY EBVs indicate the animal is expected to produce progeny that yield a higher percentage of saleable beef from a 400 kg carcase.
Intramuscular Fat
Intramuscular Fat (IMF) EBVs are estimates of genetic differences between animals in intramuscular fat (marbling) at the 12/13th rib site in a 400 kg carcase.
IMF EBVs are calculated by measuring intramuscular fat in the longissimus dorsi between the 12th and 13th rib via either live animal ultrasound scanning or direct measurement of carcases in the abattoir, and/or genomic information. IMF EBVs are expressed in percentage units.
Higher IMF EBVs indicate the animal is expected to produce progeny with a higher percentage of intramuscular fat (marbling) in a 400 kg carcase.
Net Feed Intake - Feedlot
Net Feed Intake (Feedlot) EBVs are estimates of genetic differences between animals in feed intake at a standard weight and rate of weight gain when animals are in a feedlot finishing phase.
NFI-F EBVs are calculated from the differences in the amount of feed consumed by animals in feed efficiency trials where animals are placed in a feedlot while in a finishing phase, and are expressed in kilogram per day units.
Lower NFI-F EBVs indicate the animal is expected to produce progeny that eat less feed per day, relative to their weight and rate of weight gain.
Docility
Docility EBVs are estimates of genetic differences between animals in temperament.
Docility EBVs are calculated from a subjective assessment of temperament when animals are between 60 to 400 days of age and are expressed in percentage units.
Higher Docility EBVs indicate an animal is expected to produce a higher percentage of progeny with acceptable temperament.
Claw Set
Claw Set EBVs (Claw) are estimates of genetic differences in claw set structure.
Claw Set EBVs are calculated from a subjective assessment of claw set on both the front and back feet (shape and evenness of claws), and are expressed in score units.
Lower Claw Set EBVs indicate an animal is expected to produce progeny with more desirable claw structure, being toes that are symmetrical, even and appropriately spaced.
Foot Angle
Foot Angle EBVs (Angle) are estimates of genetic differences in foot angle.
Foot Angle EBVs are calculated from a subjective assessment of foot angle (strength of pastern, depth of heel), and are expressed in score units.
Lower Foot Angle EBVs indicate an animal is expected to produce progeny with more desirable foot angle, being a 45-degree angle at the pastern joint with appropriate toe length and heel depth.
