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FEATURE

The future of fish meal replacement:

Cotton Protein This high-protein, palatable feed ingredient comes from the cotton plant – and is available today

I

by Tom Wedegaertner, director of agricultural research, Cotton Incorporated

n the 1985 movie Back to the Future, time travelers visit 2015. By pure coincidence, the date they visited coincided with Aquaculture Europe 2015, giving attendees the opportunity to speculate about what aquaculture will look like in another 30 years. An exciting prediction was made: by 2045, more protein from the cotton plant will be used in aquaculture feeds than that from fishmeal. The good news is we don’t need a tricked-out DeLorean time machine to take us to the future to confirm that prediction, because the future is right in front of us. The industry’s quest for a sustainable, plant-based protein to meet Table 1: Reported tolerance of various aquatic species to gossypol in the total diet

Species

Maximumtolerance, ppm (FG)

Toxic Effects Description

Reference

Channel Catfish

800

No adverse effects for growth or blood

Yildrim-Aksoy et al. (2004b)

Channel Catfish

336

Reduced growth

Barros et al. (1984)

Tilapia (O. spp.)

520

Reduced growth, increased liver gossypol level

Mbahinzireki et al. (2001)

Juvenile Rainbow Trout

250

Reduced growth, increased liver gossypol level

Roehm et al. (1967)

Adult Rainbow Trout

495

Normal growth, lower hematocrit & hemoglobin

Dabrowski et al. (2000)

Rainbow Trout

232

Reduced growth and reduced hemoglobin

Dabrowski et al. (2001)

Pacific White Shrimp

1100

Reduced feed intake, reduced growth, high mortality

Lim (1996)

current and future demands takes us to a present-day cotton field. Worldwide, the annual cotton crop produces about 10 million metric tons of pure protein. This is equivalent to 16 million metric tons of fishmeal, or four times current fishmeal production. It’s no secret that at current worldwide growth rates, which currently stand at approximately eight percent annually, the aquaculture industry will soon require fishmeal in volumes far

beyond that which the oceans can sustainably provide. The United Nations’ FAO reports that fish populations targeted for fishmeal production could be depleted by 2030. Cottonseed protein, byproducts of cotton production, are expected to be an excellent and far less costly – financially and environmentally – replacement for fishmeal in aquaculture applications.

Unlocking cottonseed’s protein potential

Although best known for its use in textiles, the cotton plant is increasingly valued for its seed, which is crushed for its oil and sold into the food industry or fed whole as a premium feed ingredient to high-producing dairy cows. In the ginning process, the fluffy white fiber is removed, leaving behind a fuzzy, proteinrich cottonseed. Proven highly palatable to aquatic animals in feeding trials, cottonseed has great potential but its use has been limited due to a naturally occurring toxin, gossypol, produced by the tiny glands distributed throughout the cotton plant. Gossypol, a defense mechanism designed by nature to discourage predation, is toxic at some level for all animals, insects and microbes – but is tolerated well by ruminants. The primary mechanism of its toxicity involves the binding of gossypol with the iron in red blood cells, severely limiting the blood’s ability to transport oxygen. Biotechnology now exists to “turn off” the production of gossypol just in the seed, and Cotton Incorporated, a notfor-profit research and marketing company, is taking steps to commercialize this ultra-low gossypol cotton variety. In the meantime, two immediate opportunities exist for aquaculture to tap the proven benefits of cottonseed as a fish meal replacement. First, all cottonseed available today can be formulated to meet some of the dietary needs of most aquaculture species. Second, a naturally glandless variety of cottonseed discovered in the 1950s is currently being cultivated on an experimental basis on about 150 acres in New Mexico, USA, providing the aquaculture industry with a very limited supply of gossypol-free cotton protein for research and evaluation. Increased demand for this product could easily result in a rapid expansion in glandless cotton acreage in New Mexico where low bug pressure allows it to be successfully grown.

Jumbo-sized plant-based alternative

In the desert of New Mexico, a commercial inland shrimp

16 | January | February 2016 - International Aquafeed

Jan | Feb 16 - International Aquafeed magazine  
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