Young animals learn plant preferences and grazing habits from their dams. If the dams have been trained to eat certain plants in certain locations, they pass this behaviour to offspring.
A number of studies have been done on grazing behaviour. Dr. Fred Provenza, professor emeritus at Utah State University, has been observing and researching grazing for 50 years. He has studied animal behaviour and consulted with stockmen and land managers around the world.
He recently spent time in Australia and Tasmania. “Some vineyard owners there want to train sheep to not eat the vines. This would be beneficial, to use sheep to eat the forage around the vines but not the vines. These vineyards have a mix of grasses and forbs in the understory and it is very expensive to mow. We are working with them to use sheep to clip and fertilize vineyards. They already graze the vineyards when vines are dormant, but they’d like to graze them during the growing season,” says Provenza. There are ways to train sheep to leave the vines alone, based on research he and his colleagues have done.
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It started with goats
When he was in graduate school at Utah State University, he and his wife did a study project in southern Utah. “The goal was to use goats to prune shrub blackbrush during winter to stimulate new growth — which is much higher in nutrients than unbrowsed plants. We were able to show that browsing would stimulate new growth. But the goats wouldn’t eat the new growth. This spurred my interest in grazing habits. We weren’t sure why the goats refused to eat the new growth even though it was the most nutritious,” he says.
“We found that ‘secondary compounds’ were present in high levels in the new growth compared to old growth. These compounds were condensed tannins; the bark was about 70 per cent condensed tannins. It was a little bitter, but it wasn’t the taste that deterred the goats. They avoided it because of what happened once the tannins got in their bodies,” says Provenza.
“At first we thought they innately knew to avoid the new growth, but we found out later that they did try it — and learned to avoid it after the first bad experience. They were learning, and really quickly. Unless a person was there, the first day when they were sampling the new growth, you’d never see them eating it,” he explains.
“We worked with chemists and obtained extracts of different compounds in the new growth. We’d put the extracts on pellets to see if the goats would avoid it. They didn’t avoid any of the compounds we tried until we finally got to the condensed tannin. We offered them pellets with the tannin on it. That first day, every one of them ate all the pellets. We were stunned, because we’d thought for sure this was the ingredient they were avoiding. So we decided to try it again the next day.”
The second day, the goats wouldn’t touch it. “We realized they were learning to avoid it, based on the consequences after the food got into the body — giving them indigestion. This was a huge discovery, because up until then people hadn’t made the connection. We all thought it was just taste, and that the animals innately know it’s not good for them, based on taste. This study taught us — and enabled us to train sheep to avoid eating vines in vineyards — that it’s the body feedback from cells and organs that changes the animal’s desire to eat foods,” he says. Feedback is how cells influence the body to eat what the cells need to thrive.
“We studied this topic for many years, looking at primary compounds (energy, protein, minerals) and secondary compounds (phenolics, terpenes and alkaloids), with relationships between the two. This led to insights into relationships amongst all the different compounds in foods, and to our realization that biodiversity is important for health through nutrition — for all creatures, including humans. All plants have different kinds of phytochemicals, the secondary compounds. There are thousands of compounds in each of those classes. All plants produce them,” says Provenza.
“When we started to study this, the main research was at poisonous plant labs, looking at a pyrrolizidine alkaloid or one of the 23 alkaloids in larkspur, which were viewed as toxins. But what we were not considering was that in small doses these can have health benefits,” he explains.
When there are many different plants on a landscape, animals learn to mix their diet and eat only a little of each. “The compounds that have an adverse effect if animals eat too much, or cause them to reach a point they don’t want any more — ensure that only a little is eaten. So the animals mix and match and eat many different things,” he says. This ensures a varied and healthy diet, containing all the different things they need.
In nature, grazing animals move over the landscape in herds, eating a variety of plants and moving on. Mob grazing simulates this, and helps promote plant diversity because all the plants are allowed to fully grow and mature before cattle come back to that part of the pasture. Favourite species are not repeatedly grazed and weakened.
“Frequent movement helps cattle learn to mix their diet. In nature, animals are always moving. It is healthy for them (and for the land and plants) to move across the landscape and encounter/utilize different foods. Movement helps them escape predators and also means parasites can’t build up,” says Provenza.
“If we can encourage movement — to new pastures — this is healthiest. There are many benefits that come from eating a variety of plants. Pasture-finished animals also provide healthy meat. Their bodies have phytochemical complexity.
Learning from Mom and nature
The culture we grow up in shapes us. “In our studies we’ve done a lot of work with wild and domestic animals, showing that you can change the culture/habits of animals. We try to observe how natural systems work, and get back in sync with this,” says Provenza.
Ranchers can utilize natural tendencies of grazing animals for better management, and can also change their habits if necessary — such as training lazy pasture cattle to climb up out of riparian areas in a range situation and use more of the upland areas for grazing. It’s all part of the culture they learn, regarding the foods they eat and places they go. Calves learn habits from their mothers. If you train the cows to utilize a range more efficiently and effectively, the calves will develop those same good habits.
“This is where we can have a positive influence. We all get into habits that are not the best, and sometimes need to be retrained.” Cattle that haven’t had to climb hills and work for their feed, or depend on someone bringing feed to them, are reluctant to change unless someone shows them another way. Cattle, just like people, quickly take the easy way if we pamper them too much and kill their creativity.
“With good stockmanship we can change the culture of a cattle herd from bottom dwellers to ambitious animals that live in the uplands. Once you change the culture you don’t have to do much, because the cows teach their offspring. The first year is the toughest, and by the third year you have the job done,” he says. When you keep replacement heifers, they already know good habits, learning from their mothers.
“For better land management, we can use cattle grazing and stockmanship, as well as strategic supplements that help cattle use plants like sagebrush. In our work we’ve used cattle and sheep for sagebrush control rather than herbicides or mechanical treatments. If we implement livestock into the system, they become a part of rejuvenating their own landscape,” says Provenza.
“We found that late fall and winter is a perfect time for grazing sagebrush. The deterrent compounds — terpenes — are at low concentration at that time, and it’s easier for the animals to utilize sage as part of their diet. Ranchers can strategically supplement cattle out on rangeland, moving them across the landscape. This creates mosaics and patches of changed vegetation. You can’t change thousands of acres all at once, but you can work at it gradually to rejuvenate the landscape, by integrating livestock into the management system,” he explains.
“We had good success in trials with sheep and cattle. Some ranchers in Oregon are now using these principles to cut winter feed costs. They don’t spend time trying to get rid of sagebrush, but use it as a forage resource.” This keeps it in balance with the rest of the ecosystem, by grazing it.