EBVs

EBV’s indicate the genetic value of an animal, and how it will perform as a parent, based on specific performance traits – half of which will be passed on to its progeny. While we will never know an animal’s exact breeding value it’s possible to make good estimates called Estimated Breeding Values (EBVs).

EBVs are published for a range of performance traits (link through to Performance traits page) and should be used in conjunction with visual assessment, such as structural soundness, temperament and fertility. When using EBVs to assist in animal selection it is important to achieve a balance between the different groups of traits and those traits that are particular to your breeding programme, markets and environment. One of the advantages of having a comprehensive range of EBVs is that it’s possible to avoid extremes in particular traits and select for animals with balanced overall performance.

Calculating EBV’s

In calculating EBV’s, the performance of individual animals within a contemporary group is directly compared to the average of other animals in the group. A contemporary group consists of animals of the same sex and age class within a herd, run under the same management conditions and treated equally. Indirect comparisons are made between animals reared in different contemporary groups, through the use of pedigree links between the groups.

Displaying EBV’s

EBVs are expressed in the units of measurement for each particular trait. They’re shown as + or –  differences between an individual animal’s genetics and the genetic base to which the animal is compared. The absolute value of any EBV isn’t critical, but rather, the differences in EBVs between animals. Particular animals should be viewed as being “above or below breed average” for a particular trait.

For example, a bull with an EBV of + 50kg for 600-Day Weight is estimated to have genetic merit 50kg above the breed base of 0kg. Since the breed base is set to an historical benchmark, the average EBVs of animals in each year drop has changed over time as a result of genetic progress within the herd.

TACE EBVs

Trans Tasman Angus Cattle Evaluation (TACE) is the genetic evaluation programme adopted by Angus New Zealand and Angus Australia for all Angus beef cattle.

TACE includes pedigree, performance and genomic information from both Association’s databases to evaluate the genetics of animals across both countries and further increase the accuracy of the EBV’s.

It uses information from the performance of the individual animal as well as its relatives, and allows for differences in environment and chance that animals have been exposed to that would otherwise bias our selection decisions.

Key features of TACE include:

• Calculating breeding values for all animals and all traits simultaneously, hence its description as a “Multiple Trait Animal Model”.
• Using performance information from relatives and progeny, as well as the individual animal.
• Using the known correlation between traits to increase the accuracy of measured traits and to calculate EBVs for non-measured traits such as birth weight or weight at later ages.
• The use of “country of origin” performance information of imported (introduced) animals.
• Adjusting for the effects of differences of nutrition, age of dam, age of calf and management group treatments. These are non-genetic differences that will affect the observed performance of the individual but are not passed onto its progeny.
• Adjusting for the effects of preferential mating of a sire to selected cows, unequal and selective culling, and competition between comparison groups.

As well as giving you EBVs for your animals, TACE also plots the genetic trend for your herd. This trend shows you the genetic direction of your herd for individual traits from year to year, and also lets you see the effect of environmental changes such as pasture improvement on your overall herd production.

Visit Beef + Lamb New Zealand Genetics for further information.