Much of the Bay cleanup effort has focused on figuring out what to do with nutrient-laden animal manure that comes out of the growing number of dairy cows and other farm animals in the region.

But, some scientists, farmers and animal experts now believe, the nutrient problem is more effectively addressed by managing what goes in the animal.

"The concept is simple," explained Maryland Del. Michael Weir, chairman of the Chesapeake Bay Commission. "Fewer excess nutrients going into the animal, and the more efficiently the nutrients are digested, the less coming out."

The commission, which represents the legislatures of the three Bay states, has taken a lead in pursuing the potential of feed management to reduce animal wastes in the watershed, even sponsoring a conference on the issue.

Pennsylvania alone produces about 25 million tons of animal manure a year. Figuring out ways to reduce that amount -- or get rid of it -- is the task of a new committee being formed by the state. Feed formulation is expected to be one of the committee's areas of emphasis.

"We think it's somewhere in our future," said Vic Funk of the state Department of Environmental Protection's Bureau of Land and Water Conservation.

The fact is that many of our nutrients to the agricultural system in this part of the world, here in Pennsylvania, are imported from outside the basin in the form of feed and grain from the Midwest," Funk said. "If it takes less of that to still get the same output from an animal, you don't bring as many nutrients on site to begin with."

Much of the emphasis in reducing agricultural runoff to the Bay has focused on promoting nutrient management techniques among crop farmers. Nutrient management takes into account variables such as soil conditions, crop types, planting times and other factors to optimize fertilizer application. By applying only as much nutrients as the plants need, there is less excess nitrogen and phosphorus to wash off the land and into streams and groundwater where they will ultimately pollute the Bay.

Although nutrients stem from many activities -- ranging from runoff from urban and suburban streets and lawns to septic systems to air pollution -- agriculture is thought to be the largest single source.

The idea behind feed formulation is much the same as nutrient management: By optimizing feed -- both the amounts and types -- it is possible to maximize the production of milk or meat while minimizing the amount of wastes produced by the animal.

"These are all things that are just really coming into focus," said George Wolff, an agricultural consultant. "I think just as we saw it was important to do soil tests [for nutrient management], I think that we're going to be finding that it's equally important to do feed tests, and then balance the rations according to what the animal needs, just as you balance the nutrient load going on the land for the various crops you're going to grow."

Researchers and agricultural experts caution that these efforts will not likely produce a "silver bullet" solution to nutrient problems stemming from the region's farms. Some ideas may not be cost effective. Many would require that farmers hire consultants to do more detailed analysis of what they are feeding their animals. But it is an area they view as having great potential.

"I think, because of all the environmental problems, that's where it's going to head," said David Brubaker of the PennAg Industries Association. "that's going to be one piece of the whole puzzle to clean up the problem. I don't think it's going to be a miracle solution, but I think it'll be a big part of the solution."

In a recent test funded by the Bay Program, the Lebanon and Berks County Conservation Districts in Pennsylvania altered the mix of food and enzymes being fed to the 54 cows at the Bethany Children's Home Dairy Farm. The food was tested to assess its actual nutritional value before being fed to the cows.

On average, milk production increased by about 7 pounds per day, while the amount of waste excreted decreased by about 17 pounds per day -- a reduction of more than 10 percent.

"As a rule of thumb," said Don Bollinger, who markets feed and is president of the Lebanon County Conservation District, "if you make the animal more efficient, you will get more production and less manure."

But the amount of reduction that can be achieved simply by optimizing feed may be limited. Regardless of the animal or the feed formulated for its diet, only a portion of the phosphorus and nitrogen consumed in the food is nutritionally "available" to the animal. The nutrients that cannot be absorbed by the animal are excreted.

Also, farmers have already made large strides toward optimizing feed over the last two decades because of economics, said George Robinson, a feed manufacturer, poultry and beef farm operator, and chairman of a committee which oversees implementation of Pennsylvania's new nutrient management law.

"You just can't afford to overfeed anything," Robinson said. "It just isn't economically feasible. You'll go broke in a hurry if you do. There's something to be gained there, but it's probably going to be a fairly small gain."

As a result, research is under way to see whether the addition of certain amino acids or other supplements to the feed can optimize nutrient uptake by the animal -- leaving less to excrete.

Amino acids affect how nutrients get absorbed in the intestinal tract. By optimizing feed formulation and achieving the right amino acid "profile", a dairy cow requires less nutrients to produce the same amount -- or more -- milk, research at the University of Pennsylvania's New Bolton Center, an experimental farm, has shown. Charles Ramberg, Jr., director of the center for animal health and productivity at Bolton, said nitrogen in the wastes can be reduced by 25 percent or more.

Achieving that requires an unusual mix of ingredients, some of which are grown on the farm, others from commodity purchases available through traditional means. "Some of these are not conventional things that a cow would normally eat," Ramberg said. "Things like fish meal, bits of blood meal, and certain mixtures or forms of ingredients that have specific characteristics."

But what works for one animal may not work for another. For example, hogs and chickens have single stomachs, while cows have digestive systems consisting of four chambers.

Single-stomached animals lack phytase, an enzyme which makes phosphorus in the diet more available to the animal. As a result, as much as 67 percent of the phosphorus in plant materials is not usable.

In the Netherlands, manufactured phytase is added to animal food, which results in the potential phosphorus reductions of 40 percent in animal wastes. Phytase was recently approved for use in the United States by the Food and Drug Administration.

But phytase is economical in the Netherlands because animal growers face financial penalties if they exceed certain limits on phosphorus production. Some doubt whether phytase can be economically used here unless ways are found to manufacture it at lower costs.

"It definitely wouldn't be (economical) for one state to use it," Robinson said. "It would have to be nationwide."

Still, that is only half the picture. Most farmers grow a portion of the feed for their animals. So it is important that the manure produced when animals are fed a different diet contain the mix of nutrients needed to grow crops appropriate to feed back to the animals while minimizing runoff potential.

"We're looking at that whole cycle of nitrogen utilization on the farm to use manure nutrients to grow the right crops to feed the cow to get the right balance of nutrients so we get the best efficiency of utilization by the cow," Ramberg said. "It's an integrated approach."

If feed changes become commonplace, they could affect other portions of the agricultural industry. It may increase demand for consultants to better analyze an animals' diet, but it could reduce demand for some of the traditional grain feeds being sold.

"If the technology that we're talking about here becomes widely adopted, the feed mills are going to take a hit like the fertilizer industry did five to10 years ago, because they can no longer make one ration or one feed and sell it to five farms," Bollinger said. "It's not going to fit five farms."

Ramberg suggested there may be some benefits to feed dealers, though, because they may ultimately be able to market more specialized feed stocks than they do now.

He predicted that some of the techniques being developed at the New Bolton Center could begin to be transferred to production farms in a year or so, although he said that making inroads would take time because of the complexities involved.

"It certainly is more work, but the payback is more milk for the same amount of feed cost, or conversely, lower feed cost for the same amount of milk," Ramberg said. "So you gain one way or the other."

And that doesn't count the benefits to the Bay, he said. "Personally, I don't think we're ever going to get to the point where there is no runoff or loss of nutrients to the groundwater in a viable agricultural operation," he said. "But I think we can certainly improve things significantly above where we are now. And if it is economically beneficial at the same time, it makes sense to go ahead and do that."