One of the realities of growing food is that life really is a cycle. In nature, plants and animals symbiotically co-exist, the animals eating the plants, the animals fertilising the plants and so on.

To live, we humans must always eat something that has already lived, and avoiding animals is not necessarily the best use of land. Beef has been getting a bad rap in the environmental stakes of late. There are grim statistics about the water use and greenhouse gas emissions associated with its production. Because of this, there’s been the suggestion that if we just get rid of meat, we’ll fix global warming – an idea I think that has been fairly well debunked. Eliminating all meat eating will only reduce greenhouse emissions by some 10 per cent.

The real problem is our relentless burning of fossil fuels, releasing vast quantities of carbon that has long been locked away underground. While I can see the massive global issues with food production – meat and dairy included – it’s important to look at the whole.

Often studies show the harmful environmental effects of eating meat, and the statistics on land clearing and methane emissions fall on the side of the ledger that suggests we shouldn’t eat any meat, particularly red meat.

I’ve had an unease about my meat eating and rearing. After all, it can take five to 10 kilos of food to get one kilo of meat. Shouldn’t we just eat that five kilos of food ourselves, sparing the animal and producing way more food in the process? Or is there something else going on?

Farming regions aren’t the same. Not all the microclimates are suited to grapes or cherries or wheat, say. Parts of our farm grow grass, but could probably never grow crops. They’re overshadowed in winter, on a slope facing south, with a punishing wind. You could try to sow a summer-only garden if the land was terraced, but there’s no crop we could plant that would make it worthwhile.

Our cattle, though, can range here. The grass, unfertilised and unirrigated, is fed by rain. And these slopes produce  thousands of litres of milk and hundreds of kilos of beef a year with virtually no labour. Our garden, much as I love it, takes nearly two full-time workers, bought-in compost and expensive irrigation to produce a not dissimilar amount of food. Food with a lower nutrient density, in terms of its fat and protein. On this land you’d struggle to be vegan. But animals, especially grazing animals, can feed themselves on things we can’t eat and produce food we can eat.

It was a pleasant surprise, then, to read some research on food production that takes the vast variation of climates into account. In their 2016 paper in Elementa, ‘Carrying Capacity of US Agricultural Land: Ten Diet Scenarios’, the authors show that in the US (and potentially globally), on the available land, you can feed more people using an omnivorous diet compared with a vegan one. Their research shows the worst we can do in terms of how many people land can feed is to have a high-meat diet (no surprises there). But they also found that the best way to feed people a healthy diet is omnivorously, from animals that range freely rather than living in intensive sheds or feedlots.

Now, ruminants in feedlots might be bad for the environment, and not the best use of land, but so is monoculture farming using fossil fuels, especially when often those monocultures (mostly soy, corn and wheat) are then fed to animals that could otherwise eat grass.

The amazing ability of animals to produce human food from stuff we can’t eat is something humans are well placed to take advantage of. Going vegan makes no sense when you look at the ecology of farms, and the best use of land. It might make sense in some cultures, and in some places, but the rest of the globe is  better off using a bit of dairy on occasion and what comes easily from nature.

The research confirms what a lot of farmers already know. Ecosystems exist in harmony when there are plants and animals, and if those animals are able to add nutrient-dense food to a diet, and possibly help keep a balanced farming ecosystem and healthy soil, then so be it. Ignore them at humanity’s peril.

When the 2016 study compared the vegan diet with nine other diets (some not well balanced), it required more land use than two omnivorous diets. In other words, a low-meat omnivorous diet requires less land than a vegan diet. Better still were two vegetarian options.

(Although, if you rear animals for eggs and milk, it might be wise or at least less wasteful to use the veal calves and roosters for meat. Just saying.)

Now, it’s important to note that the study looks at the US in particular, where 70–80 per cent of the grain grown is fed to livestock, and the average foodstuff on a supermarket shelf has travelled about 2400 kilometres.

The study recognises that farming systems are complex, that dealing with nature means dealing with animals, even if you grow grains or tomatoes, and that we can use animals in a thinking, caring way, and still feed ourselves. It’s not, of course, an excuse to continue the enormous overuse of poorly raised meat. We grow enough food already, globally, to feed one and a half times the world population by most estimates.

The problem with global hunger and malnutrition isn’t farming per se, but politics. And that’s a harder fix.

This is an edited extract from On Eating Meat by Matthew Evans. Murdoch Books, $32.99. Available now.