Cottonseed meal is an alternative protein source in shrimp diets to replace fishmeal. Cotton plants possess a high crop production priority since it provides fiber, a renewable resource for fabric manufacturing, as well as edible oil and protein for human and animal consumption, while its cost is considerably lower than soybean meal and fishmeal.
A team of U.S. researchers analyzed the extrusion processing potential of glandless cottonseed meal (GCSM) in extruded shrimp feed. Five different diets with different fish oil concentration and constant GCSM content were extruded. Extrusion temperature, screw speed and moisture content were varied.
Obtained optimal extrusion conditions were extrusion temperature of 130°C, 14% extrusion moisture and a screw velocity of 180 rpm. Fish oil content may increase the palatability of the extruded feed, but results showed that it negatively affects the expansion index of the product. The optimal fish oil content to obtain an optimal expansion index was 2%.
Optimal extrudates with GCSM had 50.5% of crude protein, which is higher than commercial shrimp feed. GCSM extruded shrimp feed showed a high protein, minerals, essential fatty acids, and amino acids content. GCSM has a high content of arginine, but diets will require amino acid complementation to cover all nutritional requirements. Mineral analyses of GCSM indicate that all minerals are within limits proposed by the authors, except iron: 0.13 compared to 0.6. Further studies are required to analyze the digestibility and acceptability of the shrimp extruded feed, researchers said.
“GCSM is an excellent source of essential fatty acids that might meet the requirements for shrimp diets on linoleic and linolenic acids as well as highly unsaturated fatty acids. Overall results demonstrate that using GCSM as a fishmeal substitute in extruded shrimp feed might be a feasible alternative to reduce feeding costs while showing high protein, minerals, essential fatty acids and amino acids content,” researchers said.
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