Have you noticed more friends and family making food choices based on what they think is best for the planet?
Red meat is often criticised as having a very large footprint. One argument is that beef cattle take up land where crops could be grown for human food. Or that cows are eating grain that humans could be eating instead. This is traditionally known as the ‘food versus feed’ debate'. But this new research provides a different perspective on protein supply.
Animal production systems differ widely across the globe in their sources of feed and competition with humans for food. We wanted to test the assumption that beef cattle production in Australia was inefficient. We found typical Australian beef production creates high-quality protein for humans. And they don’t compete with us for food.
The work gives our red meat industry a benchmark for the first time. And it paves the way to better understand efficiencies in other protein production systems.
Net protein contribution
In our study, we used a relatively new concept called ‘net protein contribution’ or NPC. This looks at the amount and quality of human-edible protein an animal production system consumes compared to what it contributes to the human nutritional supply. A number greater than one means a positive contribution.
Beef cattle in Australia start off grass-fed, grazing on pasture that farmers may supplement with grains or hay in times of shortage. About 50 per cent stay grass-fed their whole lives. The other 50 per cent spend most of their lives on grass. Then they move to a period in feedlots to bring them to market weight faster. This is also known as finishing. There they’ll typically receive some grain that humans could also eat.
Our research shows typical Australian grain-fed, or grain-finished, beef has a net protein contribution of 1.96. In other words, they create almost twice the human-edible protein they consume.
Inedible feed to edible protein
The feedlot sector increasingly uses by-products that humans can’t eat, while still meeting the nutritional requirements of cattle. Examples include spent grain from bio-alcohol, feed-grade grain and cottonseed.
Grass-fed cattle (that may eat very small amounts of grain) produce almost 1600 times the human-edible protein they consume. Cattle that graze only on grass or hay their whole lives don’t eat any human-edible protein at all. Their net protein contribution to the human nutritional supply is so high it's literally off the scale.
What do we mean by ‘human-edible protein’? It is protein humans can choose to eat, like meat or wheat, for example.
Proteins are made up of amino acids. The different protein types contain different amino acids, some of which are essential to human nutrition. The Food and Agriculture Organization of the United Nations has assigned scores to food proteins. They base the scores on the amino acid balance, digestibility and ability to meet human nutritional requirements.
So, not only do cattle create more protein than they consume. They turn low-quality proteins from a human nutritional perspective into high-quality protein with a more balanced amino acid profile.
To apply NPC to typical Australian beef enterprises, we used our model of ruminant grazing systems, GrassGro. We took the UN's protein scores into account along with real-world inputs and outputs of beef enterprises. These included methane emissions, historical climate records and grain-based commercial feedlot diets.
Based on this, we found beef supply chains in Australia are efficient at turning a diet that contains very little or low-quality protein into lots of high-quality protein that meet human nutritional requirements.
The methane story
The microbes in a cow’s stomach turn indigestible cellulose from grass and hay into human-edible protein. Unfortunately, they are also the culprits when it comes to methane output.
Methane emissions from Australia’s ruminant livestock are currently 9.5 per cent of our total greenhouse emissions. We're helping the sector move to being carbon neutral by 2030. This includes ideas like feeding seaweed to cows to reduce their methane emissions by about 80 per cent.
We've studied how much methane different systems produce. On average, grain-finished beef generated 30 per cent less methane per unit of beef than grass-fed. This difference is largely because grass-fed animals grow more slowly, so they're on the planet longer. It shows that if you take sustainability into account in your food choices, the picture can be complex.
Not competing for land
Part of the efficiency equation for Australian beef is that cattle mainly graze on land we can’t grow crops on. This is because of its terrain or soil type. In fact, Australian Bureau of Statistics' land use data show that since 2010 less than four per cent of Australia's agricultural land is used for growing crops.
A cow needs to eat around 25 kilograms of feed to produce one kilogram of beef. But us humans can eat none or only some of that 25 kilograms. So in terms of human-edible protein – one kilogram in and 1.96 kilograms out – the perspective looks quite different.
All up our work suggests that cows can be a good use of agricultural land for contributing valuable protein to our food supply.
This research was undertaken as part of our Future Protein Mission. The Mission aims to improve the productivity and sustainability of new and existing Australian protein industries through science, innovation and technology.