Effects of replacing soybean meal protein with cottonseed protein concentrate on the growth condition and intestinal health of Nile tilapia (Oreochromis niloticus)

With the development of processing technology, cottonseed protein concentrate (CPC) has been widely used as a new protein source to replace fish meal in aquaculture. But whether CPC can replace soybean meal still needs investigation. A ten-week experiment was designed to evaluate the impact of replacing soybean meal (SBM) protein with CPC at different levels (CPC0 [0%], CPC15 [15%], CPC30 [30%], CPC45 [45%], CPC75 [75%] and CPC100 [100%]) on Nile tilapia (Oreochromis niloticus). The results showed that 45% or higher CPC substitution significantly retarded the growth performance. Increased intestinal permeability was found in the CPC75 and CPC100 treatments. To investigate whether the residual gossypol is account for the intestinal dysfunction, an 8-week feeding trial including a control diet (CON), a control diet supplemented with 150 mg/kg gossypol (ML) and 300 mg/kg gossypol (MH) treatments, was conducted. The results showed that the transepithelial resistance (TER) was significantly decreased in MH treatment. In conclusion, the replacement of 30% SBM protein by CPC can be used for Nile tilapia's dietary needs, while 45% or higher CPC substitution of SBM influenced the intestinal health and growth condition of Nile tilapia.