Less feed, more milk

By Samantha Tennent

Measuring the feed conversion efficiency of stock can lead to better breeding calls.

Afarmer may have two cows of similar size and similar levels of production but there could be a 20% difference in their feed consumption. Data has been showing that animals with high feed conversion efficiency consume 17-24% less feed than their inefficient counterparts.

With environmental pressures, rising input costs and a growing population to feed, efficiency is becoming increasingly important. Fortunately, there are ways farmers can accelerate genetic gain for feed conversion efficiency in their herd.

“It’s a pretty exciting concept,” said Brett Fitzhenry, genetics product manager at STgenetics.

“Feed conversion efficiency has a heritability of around 0.24, which can be higher than milk production and farmers can use bulls with high genetic merit to target gains in their herd.

“There’s also the opportunity to genotype their cows to identify which ones are more efficient, and speed up progress even further.”

STgenetics has an index, EcoFeed, which measures feed conversion efficiency, known as residual feed intake (RFI). The RFI is a way to measure what a particular animal is eating compared with what they were expected to eat based on their performance and maintenance requirements.

“EcoFeed as an index is used widely internationally, particularly in the United States, and when it is built into a farmer’s breeding programme they can target it to make faster gains,” Fitzhenry said.

“Efficient animals consume less feed than we’d expect based on their size and what they are producing and that’s a win for a farming business because it helps reduce costs and makes feed go further.”

If cattle are consuming less feed while maintaining the same or higher levels of production, there will be less land needed to produce feed, less fertiliser and pesticide used to grow feed, less water and energy used to irrigate land for feed, and less fossil fuel for tractors and other farm equipment.

“There are plenty of environmental and sustainability impacts to consider, particularly the positive correlation between reduced feed intake and greenhouse gas emissions, as more efficient animals will produce less methane, manure and carbon dioxide per unit of production.

“And there is a connection with water too: high feed conversion efficiency cows use less water than low cows to make a unit of milk.”

STgenetics began extensive research into feed conversion efficiency in 2014. There is a lot of data produced in the US and the principles remain the same across any system. The index has been utilised in New Zealand since 2017 and it is getting more attention as costs are scrutinised from all angles.

“Feed is such a variable input cost for farmers and it’s a great opportunity to be able to identify the animals that require less feed per unit of product and utilise that to impact net profit.”

Through their research, STgenetics have developed two types of EcoFeed indexes for dairy animals, EcoFeed heifer and EcoFeed cow. The heifer index predicts the feed conversion efficiency of heifers in the growing or rearing phase of life, and the cow index predicts the feed conversion efficiency of a cow during lactation.

The two indexes are positively correlated, which means there are no negative impacts when selecting either. When making breeding and replacement decisions, farmers should identify genetics with their ideal production, reproductive and health traits while considering superior scores for lifetime feed conversion.

EcoFeed scores can also be applied to beef sires, where calves from bulls with a high score will consume less feed than calves from sires with lower scores, without negatively affecting growth or performance.

“Basically, some animals are genetically programmed to convert feed more efficiently and farmers have the ability to identify who they are and make breeding decisions based on that information.”