A curl of smoke wafting from a wigwam sawdust burner used to be a common sight in Oregon timber towns. Unless sawdust was burned, people would have been buried in the stuff. It was a waste product without much value and in seemingly unlimited supply.
Times changed. Timber supplies dwindled. Wigwams were outlawed in the mid-1970s for polluting the air. Instead of burning it, Oregonians found uses for lumber mill waste: to make fiberboard, paper and cardboard, and to furnish the growing horticultural industry with pots, compost and mulch. With declining timber supplies and increased demand, the price of sawdust skyrocketed, up to five times its former cost.
The higher cost of sawdust affected another, unlikely Oregon industry: producers of broiler chickens. Oregon’s broiler producers alone once used about 75,000 cubic yards of sawdust to raise 22 million broiler chickens per year. The broilers are raised in huge houses, thousands at a time, on a two- or three-inch-deep layer of sawdust that insulates them from the cold, absorbs water from their droppings and soaks up any spilled drinking water.
But the law of supply and demand is changing chicken production. Oregon chicken producers are searching for a cheaper bedding material to raise their birds. And OSU Agricultural Experiment Station poultry science researcher Harry Nakaue is leading the way.
Twenty years ago, Nakaue started thinking about sawdust—that someday, the Oregon’s broiler industry’s cheap and plentiful bedding supply might become scarce or expensive.
"In the early 1970s, experts in the forest industry predicted that by the end of the decade, wood shavings and sawdust would not be available for agricultural use because the materials would be completely utilized in the manufacture of further processed wood products,” said Nakaue, professor of animal science at OSU.
What else could be used that would be insulating and absorbent, as well as cheap and plentiful?
In other regions of the country, broiler producers raise chickens on bedding made of rice hulls, peanut shells, ground corncobs, peat moss, cocoa bean shells, shredded newspaper or other agricultural and industrial byproducts—whatever happens to be in local, plentiful supply.
What might be in plentiful supply in Oregon these days?
Oregon’s grass seed industry used to burn hundreds of thousands of acres of grass seed straw each summer to rid its fields of stubble and disease. But public pressure forced Oregon’s legislature to order dramatic cuts in field burning.
“I knew that the most likely substitute for sawdust in broiler houses would have to be locally available in large quantities for an indefinite period in the future,” said Nakaue. “There was a legislative mandate for dramatic reductions in field burning in western Oregon, so grass seed straw seemed to be a good choice for the 1990s.”
Nakaue was already familiar with the use of straw for broiler floor litter. In the mid-1970s he and his associates in OSU’s Department of Poultry Science (now part of the Department of Animal Sciences) experimented with cereal straw as a substitute for sawdust and wood shavings. In those days, since grass seed fields were burned after seed harvest, cereal straw was the most plentiful substitute for wood shavings and sawdust. As long as it was chopped into short lengths and supplied at certain minimum depths, Nakaue’s research showed cereal straw to be an adequate substitute for sawdust bedding for broilers.
But sawdust and wood shavings prices stayed low through the 1970s and most of the 1980s, as timber harvest was in its heyday. Sawdust remained the bedding of choice.
By the late 1980s, however, the price of sawdust and wood shavings began to rise steadily. The horticultural, paper and particleboard industries blossomed, all competing for the dwindling supply, driving prices up.
“The growers were getting desperate for a substitute for sawdust,” said Jim Hermes, a poultry specialist with the OSU Extension Service. “It used to cost the growers about $180 per house for sawdust. Now it costs up to $800. And some producers have eight houses. That’s a big price difference. Some growers were struggling trying to pay for sawdust.”
In the early 1990s, Nakaue began to experiment with chopped grass seed straw as a bedding material in broiler houses. With the help of a grant from the Oregon Department of Agriculture’s Field Burning Initiative, Nakaue and Hermes conducted experiments at OSU and on a commercial broiler farm to test the suitability of grass seed straw for bedding material. They tested grasses widely grown in Oregon for lawn and golf course seed—annual rye, fescue and orchard grass.
About 1 to 1.2 million tons of grass seed straw are produced each year in Oregon’s Willamette Valley. “The supply is virtually unlimited,” said Nakaue.
But just because something is cheap and plentiful doesn’t mean the broiler industry can necessarily use it, he said. The wrong kind of litter material can cause serious problems for producers, running them out of business. Nakaue and Hermes’ studies are crucial to the industry’s adoption of a new bedding material.
“Proper bedding or litter material placed on the floor in broiler houses is an essential item in broiler production,” explained Nakaue. “Without good materials, there will be a poor chicken house environment, increased incidence of disease and reduced bird performance. Producers would be unable to compete without good bedding.”
It takes seven weeks to raise day-old chicks to a 5-pound broilers. If these broiler chickens don’t have good, absorbent bedding, there’s a greater potential for disease and less weight gain. Also, problems such as breast blisters may result in reduced “carcass quality,” explained Hermes.
To test the effectiveness of the new litter material, Hermes and Nakaue reared broiler chicks in different types of chopped grass seed straw. They determined “litter caking,” the amount the bedding cakes up with manure and moisture with each type of straw—chopped annual rye grass, perennial rye grass, fescue, orchard grass, and pelleted rye grass straw. They compared its performance with that of traditional wood shavings/sawdust litter material for broiler production.
In another experiment, they looked at different densities of broilers grown on chopped straw versus wood product litter to see if chopped grass straw could provide good bedding for as many chickens per pen as sawdust and wood shavings. They studied the chickens’ foot condition to see whether there were skin lesions or leg abnormalities, as an indication of overall health. They also looked at “feed conversion,” the amount of feed required to produce a pound of broiler at different densities in pens.
They also investigated which method of chopping the straw produced the best bedding—flail mower-chopped, straw that is ground against a screen into shorter pieces versus machine-sliced straw with longer pieces. The shorter flail-mower chopped straw had less caking and made better bedding.
“The grass straw works best as bedding if it is chopped short,” explained Nakaue. Longer straw tends to promote severe manure caking and produce more problems in the birds than straw chopped into short lengths.”
Overall, chopped annual rye grass and pelleted rye proved more suitable than the other grass straw types, said Nakaue.
“During all these experiments, we had no notable loss in productivity using chopped grass seed straw,” said Hermes. “In fact, we had almost all gains.”
Bernie Gamble raises five to six cycles of broiler chickens per year in his large operation outside Junction City, Oregon. He is one of the practicing pioneers in using chopped straw for his chicken barns.
“Two or three years ago, Dr. Nakaue suggested I try using chopped straw,” said Gamble. “More and more producers are beginning to use it. The word is getting out.”
“It costs me somewhere around $40 to $80 to fill one barn with sawdust, and it only costs me about $10 to fill a barn with straw,” he said. “Using chopped straw is probably saving me thousands of dollars per year.”
There’s still some things to be worked out, though, he said.
“The trickiest thing is to figure out how to chop up the straw,” he said. “I put it through a rotary combine to break it up. But the straw is a little harder to deal with in the winter, so I still use some sawdust in the winter.”
Not only does Gamble raise broilers, he makes and sells composted chicken manure from the used litter he cleans out of his eight broiler houses.
“The organic growers love it,” he said. “The composted chicken manure with grass seed straw rather than sawdust has fewer terpenes (undesirable oils found in conifer trees) in it. Organic growers like it better.
“The market is hot for my compost. I’ll probably run out this year. It’s hard to believe that at one time I couldn’t even sell the stuff—I had to pile it up and try to give it away. Now I can’t make enough of the stuff,” chuckled Gamble.
Used straw litter also can be used as a cattle feed if mixed with silage or other feedstuffs, said Hermes.
Nakaue and Hermes estimate that about half of Oregon’s 60 broiler producers are using some chopped grass straw as broiler bedding.
“Some growers are a little scared that the birds won’t perform as well on straw as on sawdust—that there will be high mortality and downgrades of the carcasses, so they are mixing it with a little sawdust,” said Hermes. “But we hope our studies will dispel their fears.”
“We figure using chopped grass seed straw is spreading by word of mouth,” he added. “Money talks. When they see how big the price difference is between using chopped straw and sawdust, they see it’s worth their while to make the switch, even though straw is more labor-intensive because it needs chopping.
“And we don’t need to worry yet about running out of grass seed straw,” Hermes quipped. “Even if every broiler producer in the state used it, plus all the producers in Washington, we would only use about 5 percent of the straw produced by Willamette Valley grass seed growers every year.”