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Title: Growth, Immune Response and Resistance to Streptococcus iniae of Nile Tilapia (Oreochromis niloticus) Fed Diets Containing Cottonseed Meal and Supplemental Essential Amino Acid as Substitute for Soybean Meal

Author
item Lim, Chhorn
item Aksoy, Mediha
item Klesius, Phillip

Submitted to: International Aquatic Animal Health Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2008
Publication Date: 6/1/2008
Citation: Lim, C.E., Aksoy, M., Klesius, P.H. 2008. Growth, Immune Response and Resistance to Streptococcus iniae of Nile Tilapia (Oreochromis niloticus) Fed Diets Containing Cottonseed Meal and Supplemental Essential Amino Acid as Substitute for Soybean Meal. In: Proceedings of XIII International Symposium on Fish Nutrition and Feeding. June 1-5, 2008. Florianopolis, Brazil. p. 59.

Interpretive Summary:

Technical Abstract: Earlier studies indicate that tilapia utilized cottonseed meal (CSM) poorly relative to soybean meal (SBM) or SBM and peanut meal. It has also been shown that gossypol was not a contributing factor, since these fish can tolerate very high levels of dietary gossypol (1,600-2,000 mg/kg diet). Moreover, supplementation of lysine to maintain available lysine at levels comparable to those of the control diets did not improve their growth performance and feed utilization efficiency. It was suggested that the poor nutritional value of cottonseed meal-containing diets may be due to a deficiency of other essential amino acids. We conducted a study to evaluate effect of substitution of SBM with CSM supplemented with lysine or lysine, methionine and isoleucine on growth performance, body composition, hematology, immunological response and resistance of Nile tilapia (Oreochromis niloticus) to Streptococcus iniae challenge. Seven isonitrogenous (30% crude protein) and isocaloric (2,900 kcal DE/kg) diets (diets 1 to 7) were formulated to contain 0 (control), 16.9, 33.7 and 50.6% CSM with added lysine or lysine, methionine and isoleucine (to maintain available lysine or lysine, methionine and isoleucine at levels comparable to those of the control diets) as substitutes on an equal nitrogen basis for 0, 33.3, 66.7 and 100% of SBM. Each diet was fed to juvenile tilapia (6.42 ± 0.16 g average weight) in triplicate aquaria to apparent satiation twice daily for 10 weeks. Survival was not affected by inclusion levels of CSM and amino acid (AA) supplementation. Weight gain, feed intake (FI) and feed efficiency ratio (FER) significantly decreased at each inclusion level of CSM with added lysine. Addition of lysine, methionine and isoleucine to the 16.9% CSM-diet (diet 5) improved the weight gain and feed intake to levels comparable to those of the control diet, but this had no effect when CSM levels were increased to 33.7 or 50.6%. FER was not affected by the addition of these AA. Whole-body moisture and ash were not affected by dietary treatments. Body protein was significantly affected, but without a clear trend. Body lipid significantly decreased in fish fed diet 4, but was similar in fish fed other diets. Red blood cell count was lowest in fish fed the highest CDM-diets (diets 4 and 7). There were no differences among the values of this variable in fish fed other diets. Hemoglobin and hematocrit significantly decreased in fish fed diets with more than 16.9% CSM (diets 3, 4, 6 and 7). White blood cell count, however, was not affected by dietary treatments. There were no significant differences among serum protein, total immunoglobulin, lysozyme and alternative complement activity of fish fed various experimental diets. Likewise, dietary levels of CSM and amino acid supplementation had no effect on the resistance of juvenile tilapia to S. iniae challenge and antibody production against S. iniae 15 day post-challenge.