Growth and physiological responses of Nile tilapia, Oreochromis niloticus fed dietary fermented sunflower meal inoculated with Saccharomyces cerevisiae and Bacillus subtilis

The aim of this study was to enhance the nutritional value of sunflower meal used as a feed ingredient for Nile tilapia by application of a solid-state fermentation process with Saccharomyces cerevisiae (YFSFM) or Bacillus subtilis (BFSFM). At 72 h of fermentation, the crude protein, lipid content, essential amino acid contents were increased in YFSFM and BFSFM, but fiber content, chlorogenic acid, caffeic acid, phytic acid and saponins were decreased. A feeding trial of 84 days was conducted to study the response of feeding YFSFM and BFSFM on growth, hematological and physiological responses in Nile tilapia. Seven isonitrogenous and isocaloric were prepared by the replacing fish meal protein with the SFM protein (0% control diet), YFSFM-25 (25% YFSFM), YFSFM-50 (50% YFSFM) YFSFM-75 (75% YFSFM) and BFSFM-25 (25% BFSFM), BFSFM-50 (50% BFSFM), BFSFM-50 (50% BFSFM) and BFSFM-75 (75% BFSFM) and fed twice daily. Growth performance and feed efficiency of fish fed diets with fish meal replaced by YFSFM up to 25% was not significantly different from the control group, whereas ADCs were not significantly different from control up to 50% of YFSFM. No significant (P > 0.05) differences were found in hemoglobin (Hb), hematocrit (Htc), red blood cell (RBCs) and white blood cells (WBCs) among different experimental diets. The control diet, YFSFM-25 and BFSFM-25 exhibited lowest value of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in Nile tilapia. The highest value of serum phosphorus and calcium content was detected in the control diet and the lowest one was recorded in YFSFM-75 and BFSFM-75. Tilapia fed diet YFSFM-75 or BFSFM-75 recorded the lowest level of cholesterol, triglycerides high-density lipoprotein (HDL-C). There was no significant difference (P > 0.05) in low-density lipoprotein (LDL-C) and the ratio of HDL-C/LDL-C of the serum of fish among experimental diets.