Grazing strategies: OSU researcher looks at advantages, disadvantages of spatial separation

Corvallis, Ore. – According to Oregon State University Assistant Professor of Animal and Rangeland Science Serkan Ates, there is an increasing trend toward grass-based livestock production throughout the world as competition between human and livestock consumption of grains increases.

As such, Ates and his team are currently researching the advantages and disadvantages of utilizing spatial separation, or a “buffet” style of grazing, as compared to “salad bar” grazing to increase the efficiency in pasture-based production systems.

Salad bar grazing, where the plants are mixed together, is a term coined in the book Salad Bar Beef by cattle producer Joel Salatin.

“Traditionally, we would mix grasses and legumes together when seeding, but over 20 years, studies indicated that if we spatially separate them and plant them side-by-side in the same pasture paddock rather than mixed together, the animals ingest the plants more readily,” says Ates.

Animal performance

One benefit of spatially separated plots, or buffet-style grazing, is an increase in forage intake and animal performance, says Ates.

He notes that many previous studies have found an increase in performance characteristics, such as live-weight gain in sheep and milk solid production in dairy cattle.

“For example, in spatially separated planting systems, instead of mixing perennial ryegrass-white clover in sowing, they can be planted side-by-side, separately and offered to grazing animals on a free-choice basis.” he explains.

Ates continues, “A 2007 Chapman, et. al. study found the impact of spatial segregation of grasses and clovers on an animal’s performance is similar to if the animals consume pastures containing 100 percent legumes.”

Agronomy

From an agronomic standpoint, Ates notes spatially separating plant species can also be beneficial for plant establishment.

“Some plants are not easy to establish. They try but are just not able to compete with the other plants, or they don’t do as well a couple years after planting,” he comments, using the examples of chicory and birdsfoot trefoil.

“If we plant birdsfoot trefoil with a competitive companion pasture species, it is often smothered and outcompeted, and we may end up having either no birdsfoot trefoil in our pasture composition or the proportion will be quite low,” Ates continues. “But, if we plant it as a monoculture separately, we can better manage plants like birdsfoot trefoil and have greater success with establishment.”

Another advantage to spatially separating plant species is the ability to customize herbicide and fertilizer application to each plant type.

“We can tailor our chemical application for requirements based on the needs of the plants, like legumes,” he comments.

However, Ates notes there are some negatives to spatially separated systems, as well.

“If we mix legumes with grasses, the grasses benefit from the nitrogen fixed by the legumes, but if we spatially segregate them, this won’t be the case, of course,” he states.

Another challenge of spatially separated systems is that the legume component of pasture has often greater weed problems.

Spatial studies

“There have been so many studies across the world, particularly in Australia and New Zealand, looking at spatial segregation,” explains Ates, specifically referencing a study by Chapman, et. al. “More recently, in the United States, I came across one study conducted at Mississippi State University.”

He notes, however, that many of the previous studies only evaluated pastures containing only two or three species.

“They mostly included one grass and one legume species, and they looked at the impact of spatial segregation,” Ates comments. “In our case, what we want to try is the comparison of the simple pasture mixtures with multiple-species pasture mixtures in both fine mixtures and separated plots to capture the benefit of some species, like plantain, chicory and birdsfoot trefoil, that have some specific attributes.”

“This should be an interesting study for us, and we’re looking to forward to planting pastures in about early October. The first grazing study with dairy cows will be in the spring,” Ates says.

Future plans

Ates explains his team is performing three different pasture grazing experiments to analyze different pasture and animal performance aspects.

“One of them is the one that I have already described,” he says.

Another study will compare grass-legume pasture mixtures with chicory- or birdsfoot trefoil-based pastures to determine which option provides greater animal and forage production, particularly in poorly drained pasture conditions.

“Normally, since we can’t graze our traditional grass-clover pastures efficiently in late winter and early spring seasons to avoid damage, the quality of grass-clover pastures declines very quickly towards summer, and often, legumes are smothered by the grasses, leading to declines of legume components of the pastures. This also increases the need for supplemental feed,” explains Ates.

He continues, “The purpose of this study aims to diversify our pastures by planting pasture species that can grow well even in soggy, waterlogged pastures.”

In that study, the team will be assessing milk production and quality, as well as production costs from each pasture combination.

“These pastures will be grazed in late spring-early summer period in Corvallis, Ore.,” he states.

The third study will utilize sheep to graze dryland pastures in different combinations of grass and annual legume species.

“These pastures will be grazed in spring 2018, and we’ll be trying to generate data on lamb live-weight gains, pasture dry matter production, botanical composition and persistence over the next two years,” concludes Ates.

Emilee Gibb is editor of Wyoming Livestock Roundup and can be reached at emilee@wylr.net.