Feed efficiency (FE) is the efficiency with which feed is utilised by the animal for productive purposes, such as growth and lactation.

Feed is the single-largest cost incurred in beef cattle enterprises, accounting for 60% to 80% of variable costs. Therefore, feed-efficient cattle are fundamental to profitable beef farming.

When we talk about feed efficiency in relation to weight gain, there are a number of key terms we need to know.

Feed conversion ratio (FCR) – or its inverse feed conversion efficiency (FCE) – had been the measurement of choice in the past. However, this is a gross efficiency measure and does not separate maintenance requirements. Breeding for FCR or FCR generally leads to selection of faster-growing animals that have a larger mature size and thus a higher feed requirement, which in turn is associated with higher costs.

Due to these concerns, it led to examining alternative feed efficiency traits such as residual feed intake (RFI) and residual average daily gain (RADG).

RFI is the difference between actual intake and predicted intake based on an animal’s gain, body weight and composition. Cattle with low RFI (efficient) consume less feed than expected based on their liveweight and growth. One advantage of using RFI as a means of selecting for improved FE is that it is independent of growth and carcase traits in growing beef cattle.

RADG is the difference between actual gain and predicted gain based on an animal’s intake, body weight and composition. This trait highlights cattle that are not only efficient at utilising feed but will grow quickly to the desired market.

The biggest problem with RFI is that although efficient animals are eating as much feed, they may also not be putting on as much weight. Animals higher in RADG will eat more to put on more. That extra feed is being utilising effectively to grow quicker.

Ireland stands in the unique position that we have all the data required to generate RADG figures for hundreds of animals due to the strenuous work undertaken by the ICBF’s Tully beef performance test centre over the last 40 years. Combined with the database of genomes available due to the BDGP programme, identification of animals with high RADG figures should be easily achievable.

With this in mind, is it time we took a look at how the current terminal and replacement €uro-Star indices are made up. As it stands, feed intake accounts for 18% in the makeup of the replacement index and 14% in the makeup of the terminal index.

We need to ask ourselves two questions: do we want high intake animals, and do we want low intake animals?

To me the answer to both is no. Nobody wants high-maintenance animals on farm, but very few want to select for cows with poor appetites that don’t want to actively forage either.

So is it time the €uro-Star indices included RADG figures rather than feed intake figures? This way, animals which have high intakes but also utilise the feed they are eating can be identified.

Is it time that pedigree bulls are reintroduced into the performance test centre in Tully to get this information first hand? It’s been six years since the first commercial cattle were brought to Tully and while we have a slight increase in information due to numbers, have we gained anything else?

So is it time to switch back? Would we be better having actual performance data from bulls available through AI rather than small numbers of their progeny which carry unknown back-breeding?

Bulls with proven pedigrees and eye appeal combined with actual performance figures on average daily gain, FCR, RFI and RADG would help significantly in taking the risk out of breeding selection.