EBV's reflect the difference that can be expected in an animal's performance relative to the breed baseline of zero for each trait. On average, half of this difference will be passed on to the animal's progeny.

EBV's are estimated because it is impossible to predict with 100% certainty the genetic merit of an animal and therefore the genetic merit of the progeny of a particular mating.

Accuracy of EBV's

Accuracy indicates the 'confidence level' of the EBV. The accuracy of an EBV depends on two major factors:

1. The heritablity of the trait. That is the proportion of an animal's superiority that is passed on to its progeny.
2. The amount of performance information available on an animal and its relatives, particularly the number of progeny analyzed. The accuracy of an EBV increases as more performance information on an animal and its relatives becomes available.

Highly accurate EBV's are very reliable; there is little risk that the progeny performance of an animal with high accuracy EBV's (above 90%) will, on average be much different than the EBVs indicate. Alternatively, the average progeny performance of an individual with low accuracy values (below 75%), may be quite different from what his EBV's indicate.

Comparing Animals Using EBV's
EBV's are a tool that will help you to make more "educated" decisions when you are choosing breeding stock. Always remember to consider the many other important traits such as structural soundness.

Group EBV's - Traits reported within the NZHA Genetic Analysis

Calving Ease EBVs: are based on calving ease (CE) scores, birth weights and gestation length information. More positive EBVs are favorable 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.

Gestation Length EBV: indicates lighter birth weights, easier calving and increased growth after birth.

Birth Weight EBV: indicates the genetic potential for birth weight. The lower the birth weight EBV of a sire the lighter is the birth weight potential of his progeny.

Milk EBV: reflects extra calf weight which is due to the genetic influence a sire has on his daughters' milking and mothering ability. Bulls with above average Milk EBVs are expected to sire daughters with above average milking potential. To improve milk in your female herd, select bulls with well above the current breed average EBV and with high accuracy. An animal's Milk EBV is usually less accurate than its growth EBVs because of the lower heritability of the trait and the time lag before the performance of the daughter's calves becomes available.

200-Day Growth EBV: is an estimate of an animal's genetic potential for growth to weaning. This trait should be emphasised if you are selecting cattle to finish for the lightweight domestic trade. It is also important to consider the maturity patterns required for this trade.

400-Day Wt EBV: is an estimate of an animal's genetic potential for yearling weight. This trait should be emphasised where you are targeting the domestic and/or yearling trade, or where you require increased weights of your vealers.

600-Day Wt EBV: is an estimate of an animal's potential for growth to maturity. This trait should be emphasised if you breed for the heavyweight export markets or if you wish to extend the growth potential of your progeny.

Scrotal Size EBV: is an indicator of fertility in males, which passes on in part to female relatives. Increased scrotal size is associated with increased fertility in male progeny and with earlier age at puberty of male and female progeny.

Days to Calving: is an indicator of female fertility based on the time between the cow's 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.

Carcase Weight EBV: is an indicator of the genetic difference in carcase weight at a standard age of 650 days. Sires with relatively higher Carcase Weight EBVs are expected to produce progeny with heavier carcases at 650 days of age.

Eye Muscle Area EBV: indicates an animal's genetic potential for eye muscle area on a standard 300 kg carcase. Sires with relatively higher EMA EBVs are expected to produce better muscled and higher percentage yielding progeny at the same carcase weight than will sires with lower EMA EBVs.

Rib and Rump Fat EBVs: are indicators of an animal's genetic potential for subcutaneous fat depth on a standard 300 kg carcase. Sires with low, or negative, fat depth EBVs are expected to produce leaner progeny at any particular carcase weight than will sires with higher EBVs. Differences between Rib Fat and Rump Fat EBVs may indicate differences in fat distribution.

Retail Beef Yield Percent EBV: indicates genetic differences between animals for retail yield percentage in a standard 300 kg carcase. Sires with larger EBVs are expected to produce progeny with higher yielding carcases.

Intra Muscular Fat Percent EBV: indicates genetic differences between animals for intra muscular fat percentage (marbling) in a standard 300 kg carcase. Sires with positive EBVs are expected to produce progeny with higher average marble scores.

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