16 October 1998

Answering the questions frequently asked on EBV

TAKE the guesswork out of buying a breeding bull at this winters sales by using of Estimated Breeding Values (EBVs) to support a visual assessment.

Judith Collins, Signet technical manager, says many breeders will supply EBV data for bulls on offer at breeding sales this winter, but producers are often unsure of how to interpret this to ensure a bull performs as well as it looks. The most commonly asked questions about EBVs include:

What are EBVs?

The way all animals look and grow is determined by both their genes and a host of non-genetic influences such as feed, disease, climate and management. Looking at and handling a bull, for instance, tends to tell us as much about his management as his genes, but only his genes are passed on to his calves. EBVs provide us with a measure of the value of these genes, half of which are passed on.

A bull with an EBV of +40kg for 400 day growth is expected to produce, on average, calves 20kg heavier at weaning than calves sired by a bull with an EBV of 0.

Because differences in management between herds are accounted for when EBVs are calculated, EBVs, Beef Values and Calving Values of all recorded animals of the same breed can be directly compared.

What is Beef Value?

Beef Value is an economic selection index calculated from several EBVs. These EBVs are combined in such a way that selection based on Beef Value will result in improvements in carcass weight, fat and conformation score, improving financial returns.

A Beef Value for a young bull of +20 means his carcass is estimated to be £20 more valuable than the carcass from a bull with a Beef Value of 0.

Beef Values cannot be compared across breeds and to avoid confusion they are prefixed with two letters which indicate which breed they refer to, for instance, CH for Charolais and SM for Simmental.

What is the Calving Value?

This is calculated from EBVs for gestation length and calving ease. It is designed to minimise costs associated with difficult calvings, by helping producers to select terminal sires which will produce calves that are born easily.

A bull with a Calving Value of +4 is expected to produce calves which save an average of £2 in calving costs, compared to calves sired by a bull with a Calving Value of 0.

Calving Values cannot be compared across breeds. Also, to avoid confusion with Beef Value, they are suffixed with the letter C – +4C indicates an estimated Calving Value of +4.

Why have two indexes?

Having two indexes provides producers with added flexibility. It means they can decide how much selection pressure they wish to place on ease of calving, and how much growth and the carcass.

How do I know if a bull is above average?

Average EBVs and indexes for each breed change every year as the breed develops, so ask a bull owner what current averages are for the breed you are interested in.

Buying a bull with above average EBVs and indexes can pay dividends in terms of heavier carcasses of better conformation, shorter gestation lengths and easier calvings. &#42