Sows at the Iowa State Rhodes Research Farm now have the opportunity to eat at either a “salad bar” or a “dessert tray.”

After nearly 3 1/2 years, ISU professors have developed a feeding system for a group of sows which moderates their individual diets. With a computerized ear tag, a sow can be identified before she eats, said Mark Honeyman, assistant professor of animal science.

When sows want to eat, they go through a revolving door onto a scale, said Steve Hoff, associate professor of agriculture and biosystems engineering. The sow’s ear tag sends a radio frequency to a computer. Once the sow is identified, feeding information can be obtained.

The computer automatically determines if the sow is gaining or losing weight and then decides if she is at her optimum weight, based on a three-day rolling average.

If the sow weighs too much, the gate opens up to a feeder with a low-energy feed. If it needs to gain weight, the gate opens to a feeder with a high-energy feed.

The feed consists of fiber and different amounts of corn to change the energy level. The major ingredient is an oat milling by-product for energy and fiber.

The pen has seven feeding stations in each of two ration areas. The sows learn the system very quickly, Honeyman said.

“The feeder allows a free choice and a lot of contentment, not only nutritionally but satiety,” Honeyman said. He said it’s the same concept as a salad bar.

The research used about 20 sows at a time, but Hoff said the system would be able to work with possibly more than 200 sows. The sows are housed in a structure with a dirt floor and a concrete floor for the feeders. The feeding machine has metal doors which open with a motorized driver, Hoff said.

“It’s truly a prototype project with duct tape and bailing wire,” Hoff said. “It’s very primitive looking but it is proven to work.”

The researchers have applied for a patent and are waiting for a business to pick up on the idea, Honeyman said.

“Now it will depend on the marketing rather than the experimenting,” he said.

Honeyman said the research was aimed at trying to help moderate-sized farmers. For example, the structure used to hold the sows is versatile so it can be used for other activities.

The sows are usually stalled in individual pens but this system allows the them to stay in a group.

The project was prompted by the animal welfare movement, out of concern for the well being of the sows.

“We wanted to find a system that would be viewed as more acceptable and still be economical for the farmer,” Honeyman said.

The research has several benefits for ISU.

“It pushes what we know a little further,” he said. “If the patent is picked up by a company and it is very successful, then ISU would benefit from royalties.”

Hoff said the research proves ISU is a leader in swine research.

“We are trying new ideas to prove they will work,” Hoff said. “Ultimately it will benefit the producers and that’s the key to our whole aspect.”