by Deborah Jeanne Sergeant
If you think that growing a good pasture is all about the plants, Sarah Flack would disagree. A grazing consultant and an author of books on grazing, Flack presented “Grazing Management: Livestock Perspective” as a recent webinar hosted by Food Animal Concerns Trust.
Focusing on pastured ruminants, Flack said grazing is about “meeting livestock needs on pasture.”
That includes nutritional needs, like energy, protein, minerals and water, as well as comfort needs, such as appealing to the animals’ herding or flocking instinct. By effectively maximizing the pasture intake, producers can minimize the cost to feed their animals.
But Flack added, “most pastures won’t provide all the minerals they need.”
She said producers can gage how well their animals are doing on pasture by looking at the rumen fill, body condition, rate of gain, reproduction, manure scoring, milk urethra nitrogen, milk production (if it’s a dairy operation), heat stress and behavior.
“As farmers, one of the most important things to do is to know your animals and know that natural herd or flock behavior,” she said. “It might be as simple as the water isn’t running into the water tub, or the paddock size is wrong or the pre-grazing high isn’t right.”
“What can we do to make it as easy as possible for cows to eat what they need to?” she asked.
How ruminants eat varies. For example, the cow’s muscular tongue wraps around tufts of grass and pulls it in to break it off with her teeth and lower gums. But sheep and goats sweep grass into their mouths with their muscular lips to bite it.
“Cows take 25,000 to 30,000 bites per day, but sheep may take over 50,000 bites per day,” Flack said. “They have a much faster bite rate which changes how they graze and how we can manage grazing.”
What they will eat also makes a difference. Flack said goats can meet all their nutritional needs through browsing; however, “dairy cows will have a hard time.”
How low they graze also matters. The tops of grasses is more digestible and higher in fiber. The middle part has less and is harder to bite off. The very lowest area, the part nearest to the ground, has the least nutrient benefits. Grazing too low also tends to expose animals to more parasites.
“Sometimes your pasture might be too short because of previous years’ over-grazing damage,” Flack said. “Or it may be hasn’t had the time to re-grow.”
Especially for dairy cows, turning animals into a pasture that’s too short may shortchange the animals on their nutritional needs.
To get the herd to eat more of the right feeds, pasture management is critical. Flack said the dry matter intake can be figured by multiplying the bite size by the rate of biting by the time spent grazing.
“Intake per bite is strongly influenced by the number of tillers per plant and the pasture height,” Flack said.
By better managing the plants, the farmer can increase the nutrition the animals eat.
Grass diversity also makes a difference. The more diverse the pasture and the more increased the density, “it improves the structure of the plant canopy,” Flack said. “It makes it easier to get more dry matter per bite.”
She also emphasizes shorter periods of occupation to allow time for plant re-growth to its ideal, pre-grazing height.
“You’ll want it taller for a cow and shorter for a sheep or goat,” she added. “When you look at parasite management, you may want to have it higher for sheep and goats. It’s a win-win situation where good management for pasture plants will create the perfect situation for maximizing pasture intake.”
By providing a good variety of plants, cows also don’t feel pressured to eat less ideal plants or to graze down desirable plants to the hard-to-digest areas near the ground.
“If the amount of less digestible fiber is reduced, cows can eat more, with faster rates of passage and more feed throughout,” Flack said. “As plants elongate and contain more of this fiber, they can’t eat as much.”
She calls the area between too mature and too short the “sweet spot” of grazing, when the plants have had sufficient time to make lots of energy and transport it for storage to the lower parts of the plant.
Flack said livestock that receive post-ingestive feedback realize they have too much high soluble protein and refuse to graze a pasture that’s not providing their needs.
“They’ll stand by the gate and baa or moo until the farmer comes to get them,” she said. “Supplemental feed choices can become important.”
Looking at the animals’ feces can help producers know if they’re providing enough nutrition for their animals through the pasture and any supplementation. Thin, watery feces or overly firm feces with pieces of undigested fodder indicate issues with what the animals eat.
“You’ll always have times of the year where you have less than ideal manure scores but it’s a good idea to keep track of it,” she said.
To maximize dry matter intake, she encourages farmers to consider forage availability, forage digestibility, palatability, post-ingestive feedback, pasture height and density, and post-grazing residual.
“Even if your soils are amazingly well balanced, minerals aren’t necessarily present in the forages in the amount the animals need,” Flack said.
Supplementing with a portable, weather-resistant mineral supplement can help out.
Flack also addressed heat stress, which can affect nutrition in a few different ways.
“Even farmers in the northern U.S. where we used to not experience much heat stress inducing weather — that management needs to be adjusted,” she said.
Shade structures, misting equipment and using silvopasture can all help keep livestock comfortable; however she warned that these solutions may also raise a few issues because of livestock crowding into one area. These animals tend to experience more fly issues and can trample the grass in the shaded area, which means they won’t graze it.
“Have paddocks where there’s shade and those with no shade so you can manage livestock,” she suggested.