Livestock given a choice of what to eat produce better milk, meat

Livestock eating more than just grass, and given a choice of what to eat, produce better meat and milk, and lead to healthier people, a new study shows.

The study by Professor Pablo Gregorini and a team from Lincoln University’s Pastoral Livestock Production Lab is connecting soil, plant, animal and human health.

“We’ve done experiments with dairy cows, with deer and with beef cattle, we are now doing it with sheep,” Gregorini said.

The studies compared a “monotonous diet” of simple ryegrass, against two other diets, one Gregorini called a “mixed diet” and another “functionally diverse” diet.

The monotonous diet was similar to what most sheep, beef or dairy farms feed today and consisted of only ryegrass.

The mixed diet planted a mix of around 30 different plant species, and livestock grazed it like a mixed salad.

The functionally diverse diet fed only five types of forages, but in this case it was planted in separate strips and livestock could choose what they ate, Gregorini said.

“It makes it easier for them decide their own individual diet, rather than a mix salad, offering key components separately and simultaneously,” he said.

Animals that grazed the functionally diverse pasture produce more milk and meat than those eating a ryegrass only or a mixed diet, with an average increase in performance of 25%, Gregorini said.

“You can produce more with less animals and finish animals faster, so there is a massive reduction of environmental impact. Animals eating a functional, diverse diet have better welfare outcomes. We have tested metabolic markers that indicate that those animals feel better,” he said.


The chemical composition of the meat and milk produced from the animals had a better metabolomic profile that meant it could be healthier for humans to eat or drink, Gregorini said.

A previous study on venison, after deer were given the option of monotonous or diverse diets, showed venison from animals that ate a functionally diverse diet held benefits for human health, brain function, cognitive function and reduced cancer, he said.

Our beef data suggested that different pastures will determine different health markers in humans, Gregorini said.

Human trials involved taking blood samples to test for different cholesterols, inflammation markers and metabolic profile before and three and five hours after eating.

Studies on beef, dairy and deer suggest that healthier soils meant healthier plants, healthier animals and probably better meat and milk, that in turn might be nutritionally better for humans.

Gregorini said traditional systems that used predominantly ryegrass pastures or fed lucerne had always made money for farmers.

“We cannot base our agricultural systems on simplicity. Those systems are simple to manage, and that\’s OK. But now society demands other things, like better environmental outcomes and animal welfare. And some parts of society demands the absence of animals on their plate in pursuit of health,” he said.


Gregorini said in moving towards a more ethical and sustainable livestock production system that considered the wellbeing of the animal, the wellbeing of the soil, the wellbeing of the land, and human health, not only the desires of the consumer should be fulfilled, but also farmers, as they are key members of our society and foodscapes.

“No farmers, no farms, no food,” he said.

The environmental impact of feeding livestock more diverse pastures was less for two reasons.

First if it allowed a farmer to, for instance, grow a lamb in 15% less time, Gregorini said.

This meant the lamb was on the landscape less and would have a lower environmental impact as its total methane and nitrogen excretion was less, he said.

Gregorini’s studies showed animals that ate a functionally diverse pasture had rumen [stomach] microbiomes that produced less methane.

These animals also excreted less nitrogen because instead of urinating it out they converted it into muscle.

Gregorini’s team also worked on a trial comparing seaweed and other bioactives as soil amendments against conventional synthetic fertiliser.

The trial evaluated the effect seaweed and conventional fertiliser had on soil health, plant health, and the chemical composition in the plant from both.

It also looked at how that affected animal performance and ultimately human health.

Gregorini said “preliminary results were exciting”.


To continue research of the effect on human health, Lincoln postdoctoral researcher Dr Sagara Kumara, who collaborated with Gregorini, now needed 24 consumer volunteers to eat lamb raised on functionally diverse diets.

The project needed people who weren\’t in optimal health to eat precooked meals the night before each test day when they will be given lamb burger to eat.

The volunteers should also have been told by their GP that they have high blood pressure, high cholesterol or impaired glucose levels, or had a higher body mass index.

The test would span six weeks and involved blood tests over a four-hour period after they finish their burgers, Kumara said.

Volunteers had to be aged between 18 and 70, and live close to Lincoln University Research facility in Christchurch.

The lipid and cholesterol levels, inflammatory markers and metabolites of people would be measured after they consumed lamb grown on a traditional feed and non-traditional forage mixes.

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