Angus breeders reminded to keep balanced approach in race for IMF

Estimated breeding values and genetic selection tools mean producers have never been more equipped to develop and predict their herd's breeding direction.

But in recent times marbling has become a buzz word and intramuscular fat has been a highly sought figure in bull selection. Very few animals that boast a high intramuscular fat figure have above average data for feed efficiency and retail beef yield.

In the TransTasman Angus Cattle Evaluation a genetic correlation of +0.15 for IMF to NFI-F means a higher IMF will equate for a higher feed intake and lower feed efficiency.

Angus Australia breed development and extension manager Andrew Byrne said research had indicated there was a negative genetic correlation between eating quality and yield, and to a lesser extent eating quality and feed efficiency in the feedlot.

This meant single trait selection for improved eating quality, would, other things being equal, lead to a reduction in yield and feed efficiency.

"The genetic correlations are however of a magnitude whereby individuals exist with genetics that are favourable for both traits," he said.

"For example, of the 50 most widely used bulls in the Angus breed in the past two years, 15 bulls have EBVs that are above breed average for both intramuscular fat and retail beef yield.

"Identifying animals with genetics that don't follow the norm of course relies on having selection tools available that accurately describe the genetics for both traits."

He said historically Angus breeders had done a good job in balancing traits with an undesirable relationship through a commitment to performance recording, such as calving ease and growth rate.

The same balance could be achieved between eating quality and yield.

"Initiatives like the Angus Sire Benchmarking Program, whereby abattoir carcase measurements are collected on large cohorts of steers, combined with modern genomic technology, will be of great assistance in achieving this balance into the future," he said.

"As they say, if we measure it, we can manage it."

He encouraged producers selecting bulls to use selection indexes that aligns with their production system and market end-point, while also paying specific attention to a handful of EBVs of importance, along with other selection criteria.

North coast Angus breeder Rodger Pryce argued producers needed to leave extreme marbling to Wagyu.

"Food conversion is very closely linked to the foraging ability of an animal so the Angus breed, particularly the females, have come to prominence or dominance worldwide for a number of reasons and one of those reasons is their ability to forage and ability to survive," he said.

"I think to actually select for traits other than those traits that has bought the breed to dominance is high risk."

In his work with an overseas dairy board some years ago Mr Pryce saw the impact single trait selection had on an animal and it could take many years to overcome genetic change.

"If you are in pig or chook industry you can change things around quick because the gestation length is so quick," he said.

"But when you say, hey maybe we have gone too far, and you try to reverse that (in cattle) you not only have thee generations of breeding females sitting in the paddock, you have got weaners and probably pregnant cows and it's a three and half year turn around before you can change that.

"We need to preserve and we need to reinforce what has made this breed really really good so we can improve on those areas that have made the breed very popular without creating genetic change."