|Li, Menghe - MISSISSIPPI ST. UNIV.|
|Robinson, Edwin - MISSISSIPPI ST. UNIV.|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: August 29, 2006
Publication Date: February 25, 2008
Citation: Lim, C.E., Li, M.H., Robinson, E., Aksoy, M. 2008. Cottonseed meal in fish diets. In: Lim, C.E., Webster, C.D., and Lee, C.S., editors. Alternative Protein Sources in Aquaculture. New York, NY: Haworth Press. p. 313-342. Technical Abstract: Cottonseed meal (CSM), which ranks second in the United States and third in the world in term of tonnage among the plant protein feedstuffs produced, is less expensive than fish meal and soybean meal (SBM) on a per unit of protein basis. The use of CSM in fish diets has limited due to the presence of free gossypol (FG) and low levels lysine and sulfur-containing amino acids, methionine and cystine. FG exist in cotton plant as a mixture of two isomers, (+)-gossypol and (-)-gossypol. FG is toxic to fish, but toxic concentrations vary with fish species. The physiological effect of FG may vary considerable depending on the diet composition, particularly the quality and quantity of protein and minerals. Following feeding, gossypol is absorbed and accumulated in fish tissues in both free and bound form. Fish accumulate (+)-gossypol in tissues at higher concentration than the (-)-gossypol although diets contain equal proportion of gossypol isomers. Gossypol also possesses anti fertility properties. Long-term feeding of broodstock diets containing high levels of CSM or FG may reduced their reproductive performance. The effect of FG on immune response and disease resistance in fish is not consistent. Moreover, since the levels of dietary FG found to improve certain immune responses and disease resistance adversely affected fish growth performance, FG appears to be of no benefit in improving the disease resistance in fish. CSM is highly palatable and readily digested by most aquaculture species. The apparent digestion coefficients of gross nutrients in CSM for most fish species are somewhat lower than those in SBM. Comparing the essential amino acid availabilities in CSM and SBM to those required by channel catfish, SBM can satisfy all the essential amino acid requirements, whereas CSM is severely deficient in lysine and marginally deficient in isoleucine and sulfur-containing amino acids. Results of numerous growth trials on the use of CSM as substitutes for higher cost protein sources appear to indicate that the levels of CSM that can be included in fish diets vary among fish species. However, due to variations in the levels of FG and available lysine content among various sources of CSM, its use is usually limited to no more than 15% of the diets.