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NMSU testing cotton-based feed for inland shrimp production

Raising shrimp in New Mexico may seem farfetched, but if things pan out with a shrimp-feed study now under way at New Mexico State University, a new inland shrimp industry might become a reality in the Southwest. The study will compare shrimp being raised on a new feed incorporating glandless cottonseed meal with shrimp raised on a commercial feed.

Colleen Caldwell, an adjunct associate professor in NMSU's Department of Fish, Wildlife and Conservation Ecology and the New Mexico unit leader for the U.S. Geological Survey's Biological Resources Division, uses a conductivity meter to check water salinity levels in a shrimp cultivation tank. She directs a research project that will assess shrimp cultivation in a closed-water system using a glandless cottonseed meal feed. (NMSU photo by Jay A. Rodman)

The cottonseed feed was developed by researchers at Texas A&M University, and the NMSU study builds on an A&M study done at a facility on the Gulf Coast. The NMSU shrimp are being raised in local Rio Grande Basin water, with salt and minerals added to replicate normal shrimp conditions, and in a closed system that could be replicated relatively inexpensively and installed almost anywhere.

Directing the NMSU study is Colleen Caldwell, an adjunct associate professor in NMSU's Department of Fish, Wildlife and Conservation Ecology and the New Mexico unit leader for the U.S. Geological Survey's Biological Resources Division. Although her research has previously focused on freshwater fish, she welcomed the chance to convert part of her lab into a saltwater environment. Students in her department were involved in the design and installation of the equipment for the project.

"Aquaculture is agriculture," said Caldwell. "Pacific shrimp, Litopenaeus vannamei, is an easy species to rear, and it has been commonly demonstrated that it is easily reared in an aquaculture environment."

Her study began July 13. A set of 150 young shrimp were randomly selected for distribution among 10 50-gallon tanks in the closed-water system she and her students developed. The shrimp were weighed prior to entering their new environments.

Since then, the shrimp have been fed daily, with a measured ration sufficient to meet their needs. The ones in five control tanks are being fed the commercial shrimp feed product, while the ones in the five experimental tanks are being raised on the glandless cottonseed feed.

NMSU agricultural researchers have been studying glandless, or gossypol-free, cotton recently in a separate project supported by Cotton Incorporated. The Alcala cotton variety lacks the glands that produce gossypol, a substance that acts as a natural pesticide but also makes the seed, including its oil and meal, inedible by humans and most animals. Cottonseed has been considered to be a low-value byproduct, although it can be incorporated in small quantities into cattle feed. Behind the NMSU-Cotton Incorporated research is the idea that the oil and the protein from glandless cottonseed could be obtained at a relatively low cost and incorporated into a variety of products, including feed for aquaculture crops.

"What we're doing here is raising shrimp in very controlled conditions," Caldwell said of her project. "We're in a desert, and water is very precious. So we've developed a recirculating system, that's 100 percent water reuse, in order to conserve water. The temperature is very important for the shrimp, so we have it about 30 degrees Celsius, as well as salinity, which is about the salinity of our oceans, where these animals actually evolved - about 35 parts per thousand.

"If we can demonstrate, fairly inexpensively and fairly easily, that you can rear shrimp, especially on a fairly inexpensive feed such as the cottonseed meal feed, I really think that this project could be picked up by average families in New Mexico who could then rear these animals in a greenhouse."

Three undergraduate students in Caldwell's department have been involved in the project. Chance Roberts led the student team, joined by Edward Enriquez and Seth Hall. Caldwell's graduate assistant, Brad Kalb, has also participated.

"I think it's an excellent opportunity to give students a hands-on experience in actually designing this recirculating system, as well as taking a species and rearing it from an immature stage up to a size which we would typically harvest if this were a commercial operation," Caldwell said.

She says this study will end after about 60 days. At that point, the shrimp are likely to weigh around 20 grams each, "just the size you want on your plate."
At the end of the study, the researchers will compare the average weights of the experimental and control groups to help evaluate the relative nutritional effectiveness of the new feed option and the commercial feed. Caldwell's impression so far is that the new feed is "competitive."

Deciding whether the cottonseed-based feed approach is commercially viable will involve more than the size of the shrimp. The economics of the situation include not only the cost of feeding the shrimp, but also other expenses involved in raising them and bringing them to the consumer. The fact that the growing system is relatively inexpensive to build and maintain would help keep producer costs down. The closed system would minimize the problem of disposing of the water. And if a local market can be developed for shrimp grown far from the ocean, transportation costs would be relatively low.

Most importantly, these shrimp will need to be tasty. Will the combination of Middle Rio Grande Basin water and cottonseed meal feed result in shrimp that appeal to the palate?

A taste test on the NMSU campus is currently being planned. Chef Maurice Zeck, who teaches in the School of Hotel, Restaurant and Tourism Management and manages the campus's West 100 Café, has been asked to design a shrimp-centered meal, which student workers in the restaurant would help to prepare. The diners will be asked for their feedback.

New Mexico is unlikely to become a leading shrimp-producing state, but if everything falls into place, locally grown Pacific shrimp could be appearing at local farmers markets in the not-too-distant future.