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

1. I
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
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, protein-
rich 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 not-
for-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
Table 1: Reported tolerance of various aquatic species to gossypol in the
total diet
Species
Maximum-
tolerance,
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)
The future of fish meal replacement:
Cotton Protein
by Tom Wedegaertner, director of agricultural research, Cotton Incorporated
This high-protein, palatable feed
ingredient comes from the cotton
plant – and is available today
16 | January | February 2016 - International Aquafeed
FEATURE

2. farmer grows out jumbo shrimp on
a diet largely made up of high-
protein cottonseed flour. New
Mexico Shrimp Company has
partnered with Cotton Incorporated
in a commercial-scale project that
demonstrates cottonseed’s usability
for aquaculture and highlighting
cotton’s contribution to improving
the sustainability of local shrimp
production.
In this arid pocket of the United
States, commercial cotton growers
have unlimited potential to grow
glandless cotton varieties.
New Mexico Shrimp Company
is set up for conducting research
and feeding trials with diets
containing varying levels of locally
grown cottonseed to analyze feed
efficiency, water quality and growth
rate. The findings are promising.
Complete replacement of fishmeal
with cottonseed protein flour has resulted in no negative effects
on performance. These results are consistent with the findings
of several research projects recently conducted by Texas A&M
University.
Recent research conducted by the University of North Carolina
concluded that menhaden fishmeal can be 100 percent replaced
by cotton protein in the diet of juvenile black sea bass, without
affecting performance. The researchers observed that diets
containing cottonseed protein were consumed voraciously by the
juvenile sea bass.
Recent studies at Auburn University found similar results with
pompano and concluded that glandless cottonseed protein is
acceptable for use in feed for Florida pompano.
Protein from the cotton plant is poised to make a significant
contribution to the sustainability of aquaculture, by extending the
supply of precious and most likely unsustainable fishmeal.
International Aquafeed - January | February 2016 | 17
FEATURE

3. The future: ultra-low gossypol cotton
While glandless cotton can be grown in New Mexico, its
susceptibility to insect pressure prevents it from being grown on
a commercial scale elsewhere. Over the past several decades,
chemical, mechanical and microbial processes have been used
to remove gossypol but have been deemed too expensive or
ineffective for successful commercial application.
The bright spot today is transgenic technology, which silences
the expression of the gene only in the seed creates an otherwise
normal cotton plant. The transgenic cotton plant produces ultra-
low gossypol seeds while retaining the gossypol component
in the remainder of the plant, keeping its associated defenses
against fungi, insects and disease. While the plant technology is
promising, it may take years to become commercially available.
In addition to regulatory issues, this technology will need to be
inserted into modern, high yielding varieties, a time-consuming
process.
Aquaculture’s insatiable demand for protein and its desire
to replace fishmeal with a plant-based protein is the cotton
industry’s motivation for investing in ultra-low gossypol cotton
varieties and ensuring a market for this high-value protein source.
Feed cottonseed today
The potential of cottonseed is astounding. Depending on
how cottonseed is processed, it can be made into a meal, flour,
concentrate or isolate with protein levels ranging from 41-93
percent.
Cottonseed is much more palatable than other plant-based
proteins and it is nutritionally very comparable to soybean meal,
with the addition of a small amount lysine. Its proven palatability
is also evident in cottonseed’s common use for baits, lures,
attractants and feeding stimulants.
Aquaculture producers can explore ways to use cottonseed meal
today, and even lower the cost of their aquaculture rations, by
understanding the levels of gossypol and the limitations of their
aquatic species [Table 1].
In aquaculture species, the toxicity of gossypol varies widely,
with catfish and shrimp being some of the most tolerant species.
This is presumably due to the lower oxygen requirements of
catfish and the absence of iron in the blood of shrimp.
Other species such as trout and tilapia are moderately tolerant
Table 2: Fish Meal and Cottonseed Meal Amino Acid Comparison
Amino Acids Fish Meal Cottonseed
Meal
CSM as a %
of FM
Lysin 8.7 4.9 56%
Threonine 1.6 3.5 76%
Cystine 0.9 1.9 268%
Trytophan 1.3 1.5 115%
Valine 5.5 4.8 87%
Isoleucine 4.7 3.5 75%
Argininine 6.3 12.4 197%
Phenylalanine 4.4 5.9 134%
Tryosine 3.6 3.4 94%
Histidine 2.6 3 115%
Serine 4.4 4.6 104%
Alaninie 6.8 4.2 62%
Aspartic Acid 10 9.6 96%
Glutamic Acid 14.13 20.5 145%
Glycine 6.6 4.4 67%
Proline 4.3 4 93%
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18 | January | February 2016 - International Aquafeed
FEATURE

4. and have been fed feeds containing low levels of cottonseed
meal without a reduction in performance.
Research and documentation exist to guide the formulation
of lower cost aquaculture rations using cottonseed meal
to replace or be used in combination with other protein
sources. The tolerance level to free gossypol of most aquatic
animals is well above what would be found in a typical diet
containing a properly processed cottonseed meal, even at
levels of 25-50 percent (Li & Robinson, 2006). When using
cottonseed meal in an aquatic diet a gossypol analysis is
essential!
Cottonseed meal is readily available from oil mills. Since
many of these mills produce a product that is used to produce
cattle feed, it is not well suited for use in aquaculture feeds,
except catfish.
It can be used at some level by requesting high-protein
cottonseed meal and working with a nutritionist to produce
a cost-effective ration that falls safely within the gossypol
tolerances of your aquaculture species.
In addition to iron, gossypol will bind with lysine, and will
require the addition of lysine and sometimes methionine in
the feed mix. Also, the addition of iron salts to the feed mix
provides additional safety when it is added at a weight ratio
of 1:1 iron to gossypol.
Feeding trials: bring a vision to life
Limited quantities of glandless cottonseed are available
to advance the understanding and use of cottonseed protein
in aquaculture. Feeding trials with New Mexico Shrimp
Company continue; meanwhile, Cotton Incorporated
seeks additional commercial partners for feeding trials and
demonstration projects.
As we learn more about how this, readily available plant-
based protein, can transform the aquaculture industry, and
support its continued growth, we realize that the future starts
today.
We recall an iconic line from Back to the Future: “Your
future is whatever you make of it, so make it a good one.”
For more information on cottonseed as a sustainable
protein alternative to fish meal, or to discuss your interest in
participating in a feeding trial, contact
International Aquafeed - January | February 2016 | 19
FEATURE