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Why Performance Test? Understanding BreedPlan How to use EBV’s
Understanding Estimated Breeding Values.
The first step is to decide what characteristics are important in your breeding program, then
select the EBV which fits that production system best. For example, if you are selling 14 month old steers and the last draft you sold could have been heavier without prejudicing your market then you should look for
a high EBV bull for Yearling Weight (400 Day Growth EBV).
Only Murray Grey GROUP BREEDPLAN EBVs or Interim EBVs with Accuracy (Acc) can be validly
compared between herds., within the Murray Grey Breed. They cannot be compared to another Breeds EBVs as they have no genetic comparison and start from different bases.
Estimated Breeding Values (EBVs)
The EBV is the best estimate of an animal's genetic merit for that trait.
Accuracy's (%)
An accuracy is presented with every EBV and gives an indication of the amount of information
that has been used in the calculation of that EBV. The higher the accuracy the lower the likelihood of change in the animal's EBV as more information is analysed for that animal or its relatives. As a general rule
animals can be compared on EBVs regardless of accuracy, however where two animals have similar EBV's the higher the accuracy would be the better choice. Animals with higher accuracy's will tend to breed more
predictably to their described genetic potential.
Calving Ease
EBVs are based on calving ease (CE) scores, birth weights and gestation length information.
More positive EBVs are favourable and indicate easier calving.
DIR direct CE indicates how this animal influences the birth of its progeny.
DTRS is daughter's calving ease and indicates how well the animal produces daughters
that have easier calving.
Birth
GL : Gestation Length EBV (days) is based on AI records. Lower (negative) GL EBVs indicate easier calving and increased growth after birth.
BWT : Birth Weight EBV (kg) is based on the measured birth weight of animals, adjusted for dam age. 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. (Heritability is 42%).
Fertility
SS : Scrotal Size EBV (cm) is an indicator of male fertility in regards to semen quality and quality. Higher EBVs indicate higher fertility. SS is also positively associated with female fertility.
DC : Days to Calving EBV (days) is an indicator of female fertility based on the time between the cows first exposure to a bull and when she subsequently calves. Cows that calve late in the season or fail to calve are penalised. This is more useful as a sire trait. Lower (negative) EBVs are preferred indicating shorter days to calving for the sire's daughters.
Growth
Milk : 200-Day Milk EBV (kg) is an estimate of an animal's milking ability. For sires, this EBV is indicative of their daughter's milking ability as it affects the 200 day weight of their calves. If a bull is to be used to breed replacement heifers and superior milking and mothering ability is required then pay close attention to the MILK EBVs. (Heritability is 10%).
200 : 200-Day Growth EBV (kg) is calculated from the weight of animals taken between 80 and 300 days of age. Values are adjusted to 200 days and for age of dam. This EBV is the best single estimate of an animal's genetic merit for growth to early ages. The vealer producer should place emphasis on the 200 Day Growth and Milk Genes. (Heritability is 20%).
400 : 400-Day Weight EBV (kg) is calculated from the weight of animals taken between 301 and 500 days of age, adjusted to 400 days and for age of dam. This EBV is the best single estimate of an animal's genetic merit for yearling weight. It should be used for producers marketing yearling cattle. (Heritability is 30%).
600 : 600-Day Weight EBV (kg) is calculated from the weight of animals taken between 501 and 900 days of age, adjusted to 600 days and for age of dam. This EBV is the best single estimate of an animal's genetic merit for growth beyond yearling age. It should be used by the Feeder Steer Producer. (Heritability is 33%).
MWT : Mature Cow Weight EBV (kg) is an estimate of the genetic difference in cow weight at 5 years of age. More moderate EBVs are generally more favourable for an efficient cow size.
Carcase
CWT: Carcase Weight EBV (kg) estimates the genetic difference in carcase weight at a standard age of 650 days. Should be viewed in relation to 600 Day and Mature Weight as more efficient beef producing cattle will not need high maturity weights to get carcase weight.
EMA : Eye Muscle Area EBV (cm²) estimates genetic differences in eye muscle area at the 12/13th rib site of a 300kg dressed carcase. More positive EBVs indicate better muscling on animals. (Heritability is 21%).
RIB : Rib Fat EBV (mm) estimates the genetic differences in fat depth at the 12/13th rib in a 300kg dressed carcase. More positive EBVs indicate more subcutaneous fat and earlier maturity.
RUMP : Rump Fat EBV (mm) estimates the genetic differences in fat depth at the P8 site of a 300kg dressed carcase. More positive EBVs indicate more subcutaneous fat and earlier maturity.
Two fat EBVs are listed as there is variation between animals regarding fat depth at the two
sites.
RBY% : Retail Beef Yield Percent EBV (%) represents total (boned out) meat yield as a percentage of a 300kg dressed carcase. A more positive EBV indicates higher percentage yield for the 300kg carcase size.
IMF% : Intra-muscular Fat Percent (Marbling) EBV (%) is an estimate of the genetic difference in the percentage of intra-muscular fat at the 12/13th rib site in a 300kg carcase. Depending on market targets, larger more positive values are generally more favourable. Marbling is important in producing High Quality Beef and especially the B3 Jap Ox Market.
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