by Tamara Scully
Sheep don’t only have to graze perennial pastures. Adding some annuals into the mix, whether to fully renovate pastures or to add forages during the summer slump, is one way to maximize forage production without adding acreage to an operation.
Adding sheep grazing into a row crop rotation with cover crops is another way to get dual use from the land and enhance soil health. While the cover crops themselves are great builders of soil health, adding sheep in a managed grazing plan only enhances their positive impacts.
The goal is to optimize forage utilization, Dr. Richard Ehrhardt, small ruminant specialist at Michigan State University, explained during a recent webinar. Grazing annuals can do just that.
Grazing annual forages
The forage quality of annuals can be very high when compared to perennials, Ehrhardt said. While adding annuals into perennial pastures increases diversity, they also have other benefits. Annuals can grow during the summer, when cool season perennials slow down, and be used to help extend the grazing season. They have a positive impact on soil health, increase the carrying capacity of the land and provide nutritious forages for the sheep.
Low producing perennial pastures can be fully renovated using annuals. Parasite loads can be reduced and soil health increased to support a revived perennial pasture with greater palatability and forage quality after a few years of using annuals to renovate the pasture, Ehrhardt said.
Annuals provide a high plan of nutrition for late pregnancy, lactating ewes and growing lambs. If birthing in pasture, the parasite load can be high, and these paddocks are good targets for renovation with annuals. The parasite load in pastures is drastically reduced by “essentially resting them by putting them through an annual forage system,” Ehrhardt explained.
The first year of perennial pasture renovation is focused on double cropping the perennial forages with annuals. No-till seeding annuals will minimize any weed and erosion concerns and reduce any soil moisture loss. Typically, the annual mix would be no-tilled into herbicide-killed pasture once the spring flush is over and growth slows. Seeding brassicas the first year and using sorghum-sudangrass or a mix of both can add a fast-growing forage ready for grazing in 30 days and which can be grazed several times in one season. These crops can also be planted in July or August and then stockpiled.
Forage radish and turnips are high-yielding and can germinate under low soil moisture conditions. Forage kale and rape hybrids are good choices too, with roughly 45% of their massive production of biomass able to be utilized by the sheep as forage.
In various studies at MSU, rates of gain were measured on a variety of annual forages, including forage turnips/BMR sudangrass mixes, forage turnips alone and BMR sudangrass alone, as well as these annuals grown in alternating strips in the field. All had good results.
“These are really good rates of gain,” Ehrhardt said. Although they are “not quite what you see on grains,” they are less costly than feeding grain and are enhancing soil health too.
The second and third year of pasture renovation involves seeding with short-term perennials. Italian ryegrass, chicory and red clover are highly digestible and high-yielding. A mixture of legumes, forbs and grasses keeps the sheep from losing weight during lactation. When compared to a perennial pasture over three years, the annual/short-term perennial system shows enhanced gain per acre and an increase in forage production over these years.
“Because we’re looking at gains per acre here, it’s also a measure of forage quality. That’s forage quality directly translating into animal performance,” Ehrhardt said.
Grazing cover crops
Another way to graze annuals is to plant them as cover crops, in either a row crop or a vegetable crop rotation, and then graze the sheep. In either system, the cover crops scavenge nutrients, protect the soil, control weeds and produce a high-quality forage, benefitting the animals and the soil.
“These cover crops are really high quality forage and can be stockpiled nicely and extend grazing and decrease stored forage use,” Ehrhardt said. “Most of the cover crops, especially if you have a small grain, you’re not really going to have a bloat problem.”
There is a balance between meeting the nutritional needs of the sheep and allowing the cover crops to do their primary job of protecting and enhancing the soil, Ehrhardt said. As the forage growth rate slows, it’s time to go in and graze them. The general rule is to graze 40% of the crop and leave 60% in residual biomass. If they are grazed earlier, it would be important to leave some additional biomass. This would also be important when compaction is a concern. Even within these guidelines, in poor growing years there is almost always enough cover crop for the sheep to graze, and cover crops are high energy forages.
“We can put a lot of sheep on these crops,” Ehrhardt said. “It’s not a typical pasture. These animals are definitely gaining weight as an indicator of the forage quality.”
High-energy cover crops will easily put gain on flushing ewes and maintain them until late pregnancy. Replacement ewes will also benefit, and cover crops offer superb nutrition when breeding ewes prior to 12 months of age. For lambs, 0.3 – 0.6 pounds of gain per day are typical when grazing cover crops, depending upon type of crop and specific management.
“You get cheap forage, high quality, you can meet the needs of late pregnancy and even finishing. There is really a low risk of (poor) crop yield,” he said. “It definitely fills a whole in a perennial-based grazing system.”
Portable electric fencing is not expensive and can be erected quickly with little labor cost. If the ground is in danger of freezing below a few inches, putting the fencing in before freezing occurs allows easy movability. Certain types of fencing (with plastic struts) can better cope with snow and ice loads.
Water can be obtained primarily from the moisture content of the grazed cover crops, which contain up to 80% water content in mid-autumn, as well as from any snow cover. As cover crops freeze and thaw their water content declines. The stage of reproduction will dictate the water requirements for sheep and needs to be considered. The general need for water will decrease 50% as temperatures drop from 72º to 36º.
Adding sheep grazing to a cash crop situation adds nutritious forages for the sheep, benefits the soil and can put money into the pockets of farmers. Using annuals to renovate or enhance existing perennial pastures offers plenty of opportunity to graze sheep, increase biodiversity and reduce the cost of purchased feeds or stored forages. Whether you are already grazing sheep and seeking new sources of forage, or are growing row crops and looking to add a livestock component, sheep and cover crops do mix.
View the complete webinar at practicalfarmers.org/2018/12/grazing-cover-crops-with-sheep.