Free Up Your Chickens!
Mar 02, 2012
Why Not Chickens?
Grass holds soil in place and keeps it from eroding. Grass root mass is like a big sponge, absorbing and retaining water. And grass’s roots are dying all the time, "putting more organic matter into the soil, which contributes to soil aggregation and better water and air infiltration, and to more diverse biological activity, nutrient release, and carbon sequestration," says Heather Karsten, assistant professor of crop production and ecology at The Pennsylvania State University. "The most fertile soils around the world developed under perennial grasslands. Animals are out there grazing their own forage, managing their own feed and spreading their own manure, so there’s not as much labor, equipment, storage facilities or energy involved for the farmer. And grazing systems, if they’re well managed, can be very profitable."
Grazing is good for nutrition.
Cows graze. Goats graze. Horses graze.
Why not your chickens?
Animals with just one stomach, like chickens and people, don’t have the digestive microorganisms needed to get all their nutrients from pasture, but there are advantages to raising even chickens on grass. Poultry raised on fresh pasture instead of stored grain get more unsaturated fats and vitamins in their diet. It’s like the difference between fresh and canned vegetables. Pasture-fed chickens can also get bonus nutrients by eating grass-dwelling insects. And grazing chickens on a pasture that has already been munched on by ruminants helps with the break-down and spread of manure.
The chickens’ diet must be supplemented with grain, Karsten says. She goes on to state that she thinks it could still be cheaper to raise chickens on pasture and grain than on grain alone. We have done our own on-farm studies on a much smaller scale than the university, but we have found that the chickens need only a very small amount of grain during the winter. From April until December, our free-range chickens don’t eat any supplemental grain, the yolks are a dark yellow/orange in color and the shells are durable and thick.
Not all grasses are equal, however. The leafier the plant, the higher the digestibility for the animal. If a pasture is overgrazed or the grass is too mature and "stemmy," the nutritional benefits fall off. And in a recent study, legumes like alfalfa and clover are higher than grasses in omega-3 fatty acids (which lower health risks including cancer, cardiovascular disease and autoimmune disorders).
Over a six-week period, Karsten rotated 25 chickens from grass to red and white clover to alfalfa, grazing them for two weeks on each species. To facilitate rotation, she designed a mobile chicken coop, known as a "CHICKEN TRACTOR," with help from students from the Agricultural Systems Management Club. The coop, which could be towed around the field on wheels with a small tractor, four-wheeler or truck (when pasture conditions permit), provided the chickens with food and water, protected them from predators, and served as a nest box. During each rotation, egg samples were taken and analyzed for levels of unsaturated fat and vitamins in their yolks. The researchers then compared eggs produced on each section of pasture to eggs taken from chickens raised in commercial cages on a typical grain diet.
They found that the pastured birds produced about three times more omega-3 fat in their eggs than did birds raised on an industrial diet. Regarding the best pasture mixes, "on average across all these periods, the mixtures highly dominated by legumes — clover and alfalfa — produced 18% more omega-3 fat than grass alone," Karsten says. Eggs from the alfalfa pasture had 25% more omega-3 than grass-produced counterparts. "In absolute amounts, this was not a very big increase," Karsten states. "But with more research and some different feeding regimes, it might go higher."
Pasturing also boosted levels of vitamins A and E. "On average, we saw about twice as much vitamin E and 40% more vitamin A in the yolks of pasture-fed birds than in the caged birds. The longer the animals were on pasture, the more vitamins they produced," Karsten says. The study confirmed three nutritional advantages of raising hens on pasture as compared to on an industry diet in cages: the increases in omega-3 fatty acids and in vitamins A and E. It also found that differences in omega-3 levels in plants have an effect on the eggs. And it showed how to manage chickens on pasture.