Since early spring, Sean Mallet's herd at Nature's Harmony Organic Dairy has been grazing irrigated mixtures of ryegrass, clover and alfalfa. The cows don't produce as well as when he was a conventional dairyman, but they're healthier, his costs are lower and he gets a premium for the milk.

“We're trying to feed the cow what she was designed to eat, and that's forage,” says Mallett.

The dairy is a new partnership between Mallett and his stepfather, John Reitsma. The family was in the conventional dairy business for 24 years. At one point they were milking as many as 10,000 cows on four separate dairies in south-central Idaho.

But soaring input costs forced them to re-evaluate their strategy.

“The price of conventional milk just wasn't keeping up,” says Mallett.

So about five years ago they bought a 750-acre farm south of Twin Falls and began converting it to organic production. About 550 acres of the farm are now in pivot-irrigated pasture.

The dairy started producing organic milk from a new double-26 swing parlor in January 2008. Milk from the 1,000-cow dairy is sold under the Horizon Organic label in several Western states. A total of about 1,400 mixed-breed (mostly Holstein-Jersey) cattle, including dry cows and heifers, graze the farm.

Making the switch to a pasture-based organic dairy took about two years of research and planning. Well-known grazing expert Jim Gerrish, who lives near Challis, ID, helped design the system.

Mallett uses two pasture blends: perennial ryegrass mixed with white clover and perennial ryegrass-bienniel ryegrass mixed with alfalfa. In mid-August, he was preparing for a fourth grazing rotation on a seven-year-old alfalfa stand that had been interseeded with ryegrass.

“The best way to extend the life of an alfalfa field and improve the forage value is to plant grass in it,” says Mallett.

The pasture is parceled into 110 5-acre paddocks and the herd is divided into four groups of about 250 cows each. Each group spends about 12 hours per day on a paddock and is moved to a new one the next day.

The cows at Nature's Harmony don't get all of their feed from pasture, but it's a significant part of their dry matter intake during summer. In late August, he estimated that the milk cows were still getting about 45% of their total feed intake from pasture alone. The remainder of their diet was a mixed ration that included hay or haylage, corn, corn silage, wheat, barley and supplements.

The cows graze from May until October, when the first hard frosts usually arrive and the grass starts to go dormant. During winter, the cows are confined to drylots and fed a total mixed ration of organic hay, grains and nutritional supplements.

Since he switched to a grass-based system, Mallett has been able to gradually reduce the amount of grain in the ration. He's cut the amount of corn in half.

“I went from 14 lbs of corn (per cow per day) to 7 lbs,” he says. “You can replace a portion of your corn with good, high-quality pasture.

“It takes time to change cows over to a high-forage diet,” he adds. But once the cows get used to it, “they love it.”

Pasture allows the animals to behave naturally and reduces their stress level, Mallett says. The grasses and legumes are rich in vitamins and minerals, and he looks for the same kind of nutritional value in hay.

“When I buy hay, I look for high digestibility, a complete mineral profile and the right balance of nutrients and minerals,” he says. “I don't just buy on protein and fiber.”

Cows can expend a lot of energy walking back and forth from pasture to a milking parlor every day, but it helps keep them fit. Burning those extra calories may lower milk production a little, but the trade-off is improved herd health, says Mallett.

The cows seem to have fewer hoof, respiratory and reproductive problems since making the switch to a grass-based system. The cull rate is about 10% — about one-third as much as on a conventional dairy, he says.

Pasture gives the organic dairy its greatest competitive advantage over conventional dairies, says Mallett.

“Besides being a dairyman, I've got to become a real good grass farmer.”

Manure management is less of a hassle than in a confined system because the cows leave most of it in the pasture where it disappears in a few weeks.

“We aren't creating huge amounts of manure that we have to export,” he says.

Organic milk prices have declined in the past year, but not as drastically as conventional milk prices. The premium over conventional milk has actually widened during the downturn, he says.

While the demand for organic food has dropped off a little, “it's still there,” he says.

A grass-based organic dairy isn't going to set any milk production records, but it doesn't have to because the costs are lower. If Mallett can make a decent living on 55 lbs of milk/cow/day rather than 85 lbs, he's happy and so are his cows.

“Even if we were still a conventional dairy, I would graze,” he says.