Understanding EBV’s

Group Breedplan analyses the growth and production attributes of beef cattle and provided predictions of the genetic merit of individual animals called Estimated Breeding Values (EBV’s)

Breedplan is logical and straight forward and provides the only solution to the otherwise impossible task of weighing up individual bull performance and adjusting for pedigree and the performance of brothers and sisters. It gives the correct weighting to all available information and then gives a value and accuracy level for each trait measured. The higher the accuracy percentage, the more confidence you can have in the figure. Without any figures selection becomes guess work. EBV’s are shown as +ve or -ve differences from the breed base. The average EBV’s for traits change over time as the breed makes genetic progress. The breed average EBV’s provide a useful benchmark for comparisons of EBV’s for individual animals.

The following is a brief explanation of the figures and what to look for. Remember, all the figures are calculated from the animal’s individual performance AND the performance of its relatives that have also been measured or weighed. This is important as it improves the accuracy of the predicted performance of the bull you purchase. For example, if the bull you purchased was light for birth weight, yet one of its parents was heavy at birth, there is a fair chance that some of your bull’s calves will inherit the grandparent’s high birth weight. Breedplan works out the likelihood of this occurring and includes it in the estimated figure. The same applies to all other measured traits.



Calving Ease (CE)

Appears on sires only and is self explanatory to a large extent. CE (DIR) is Calving Ease direct and refers to the amount of calving difficulty you can expect from this bull directly from the cows he is joined to. CE (DTRS) is Calving Ease daughters and refers to the amount of calving difficulty you can expect from his daughters. A plus figure in both instances is good.


Gestation Length (GL)

Some cattle have shorter pregnancies than normal and some longer pregnancies. As growth starts from conception, generally a bull with short gestation length EBV. It also means that the cow has more time to recover from calving to get back in calf for next year. A negative figure here is good.


Birthweight (BWT)

Birthweight generally applies mostly to those looking for a heifer bull. Generally at Warwick Court we get a little nervy when we go much above +4.5 for own heifer joining, although some areas seem to be able to tolerate more birthweight than we can on the Monaro. Even if you are not looking for a heifer bull, keep in mind that a bull with a big birthweight will sire heifer calves and you may run into problems when his daughters calve down. In a well designed program, birthweight EBV should be able to gradually increase as the size of your heifers at 2 years of age increases through selection for improved growth rate. A low figure here is good, especially over heifers, bet be careful that it does not get so low that calf mortality starts to increase. Also, you should challenge your heifers to be able to handle higher birthweights, otherwise calving ease will go the wrong way.



200, 400 & 600 Day Growth

These figures indicate the sort of weight differences you can expect from the progeny of these bulls (as an average) at 200, 400 and 600 days of age. In other words, if you have two bulls and for 600 Day weight one is +70 and the other is +80, you could expect the bull who is +80 to sire calves tat would average 5kgs more bodyweight (as the sire provides half the genes to the calf, that is 10kg divided by 2) at 600 days than the bull who is +70. A plus figure in all areas is good, relative to your production, provided birthweight does not get out of control.

Mature Cow Weight

Provides an estimate of the genetic differences between animals n cow weight at 5 years of age. Obviously smaller cows have less maintenance requirements and those that can still wean heavy calves are valuable however remember there is a high negative correlation between low Mature Cow Weight and growth meaning selection for this trait can put pressure on growth rate of progeny. More efficient “easy-care” cows have a MCW lower than their 600 DWT and we select for this.



Milk is the figure that most people find hardest to understand. How can you work out how much milk an animal is capable of producing in its offspring with out actually milking them and measuring the quantity? Milk is obviously an important consideration especially for those beef producers turning calves straight off their mothers. Too much of a good thing can lead to udder problems and also result in failure to get back in calf early, especially if a really good milker hits a tight Spring. There are some cows that will milk well and yet still retain enough body condition to start cycling soon after calving. They are obviously very desirable. A plus figure here is good but beware of the problems associated with extreme production.



Scrotal Size (SS)

There is a strong correlation between scrotal size and both male and female fertility. Bulls with big testicles generally sire more fertile daughters. You may notice a discrepancy between scrotal size on sale day and the EBV. This is because testicles, like just about everything else, grow at different rates in different bulls and rankings will therefore change. As with all Breedplan analysis, information on relatives also has an effect. The measurement for the EBV was taken at the same time as we started to program the heifers for their AI program back in early September. The reason we did this was to identify those bulls who failed to reach sexual maturity at the minimum age we want our heifers to be cycling. We cull all bulls who fail to reach a minimum of 30cm at 12 months of age as these animals, if allowed to go through into the sale group, will be more likely to breed heifers who will not get in calf early. A plus figure here is good.


Days to Calving (DC)

This figure only appears on sires and is an indication of the time taken for his daughters to get back in calf after calving. Some cows take longer to return to their normal heat cycle after calving than others. Those that recover quickly and need fewer days before they get back in calf are obviously more worthwhile having around. A minus figure here is good.



Carcase Weight (CWT)

Carcase weight refers to the difference you can expect in the weight of this bull’s steer progeny when slaughtered at 650 days of age. Remember that this is an EBV and therefore the actual contribution of this trait to the bull’s offspring is half of the number published. This is because only half of any animal’s genes comes from the sire. The other half comes from the mother. A high figure is good.


Eye Muscle Area (EBA)

This trait is measured by ultrasound when the bulls are approximately 15-18 months old. As muscling is consistent throughout the body, EMA is a good indicator of overall muscle content when the measurement is taken and analysed in the light of total body weight. It is actually impossible to have an animal with more meat in his hindquarter than in his forequarter, or vice versa. Many years ago, Professor Butterfield dissected numerous carcases from many breeds to prove that as a proportion of total muscle weight, almost exactly the same amounts of muscle were found in various parts of the animal regardless of breed or physical appearance. Despite general opinion to the contrary, it has been recently proven that increased muscle is not linked to poor fertility or calving difficulty. A plus figure here is good.


Fat Depth – Rib & Rump

Also calculated from ultrasound measurement, high fat depth EBV’s will mean bulls that leave fatter carcase and lower lean meat yield. However, recent research has shown that bulls that are positive for fat generally sire more fertile daughters than those that are negative, all other things being equal. Care has to be taken, therefore, not to select poorer types that lack doing ability and constitution resulting in low fertility. This EBV needs to be kept in balance and extremes of plus or minus should be avoided.


Retail Beef Yield (RBY%)

This figure is calculated to give you the expected amount of retail beef as a percentage of the total carcase weight in a 300kg carcase sired by this bull. Again you need to understand that as animals receive half from their mother and from their father, this figure needs to be divided by two to ascertain just how much is a result of the bull’s influence.


Intramuscular Fat – Marbling (IMF%)

As abattoir data is always slow, there are big benefits in measuring live cattle. The Animal Genetic and Breeding Unit (AGBU) at Armidale with Meat Research has been researching marbling scanning since 1996 and has come up with some very Corporation, CRC and Breed Society support encouraging results for genetic evaluation. IMF% and actual marble score are reasonably well correlated and therefore selection on IMF% will improve marbling. To further improve accuracy, the figure or IMF% calculated by Breedplan also includes abattoir data and overseas EPD data, as well as ultrasound. The US data on marbling is generated purely from abattoir carcase information. A plus figure here is good.