Jon Robison turns a corner and walks into a snack-lover's paradise: a vat piled high with potato chips of every kind - barbecue, sour cream and onion, and plenty with just plain salt.

But hold the beer and football. These lip-smacking snacks are not for him or any other human. They're being stored for cows."I'm going to say this is not real common," said Robison, an animal nutritionist who oversees the dairy at Fresno State University. "But I think it's a lot more common than people think."

Robison said he's been feeding potato chips to beef and milk cows for about 10 years because they provide the animals with an easily digestible and relatively cheap source of energy.

The chips are mixed in with other feed ingredients, usually at a rate of about 15 percent but sometimes higher.

The chips come either directly from snack food companies or through feed suppliers.

"Potato chips that don't go into the bag will find their way into livestock feeds," said Nick Ohanesian, a member of the American Registry of Professional Animal Scientists, who works as a dairy consultant.

In processed chips, the starch has been broken down further than in its natural form and requires less energy for digestion, Robison said. The chips contain anywhere from 22 percent to 28 percent fat, which has more than twice the amount of energy as starch, he said.

"All that oil they're cooked in adds even more to the energy value," he said.

The chips also allow him to reduce the amount of corn in his feed. He pays about $125 a ton for corn, roughly $40 more than the cost of an equal measure of chips.

Unlike most cattle farmers, he buys the chips unmixed, allowing him to experiment with the rations he puts in his feed, which will also typically include alfalfa, barley and corn.

"There are many who would advocate not using them, mostly because of the nutritional variability (of potato chips)," Robison said. Most farmers don't like to vary their cows' diet because it affects milk output.