Trans-gauche-trans disulphide conformers measured by means of FT-Raman may be predictors of apparent digestibility of crude protein in feather meal fed to rainbow trout (Oncorhynchus mykiss)

The present study assessed the suitability of an FT-Raman method previously developed in our laboratory to predict the digestibility of crude protein (CP) in feather meals (FeMs) fed to rainbow trout (Oncorhynchus mykiss). Since we have already demonstrated that this FT-Raman method could efficiently predict the digestibility of CP in FeMs fed to broiler chickens, we decided to assess the suitability of this method in rainbow trout nutrition. A digestibility trial was conducted to assess the apparent digestibility coefficient (ADC) of CP in 7 FeMs of different origins in rainbow trout. Levels of disulphide conformers trans-gauche-trans (SStgt), gauche-gauche-trans (SSggt) and gauche-gauche-gauche (SSggg) in the 7 FeMs were studied by means of FT-Raman spectroscopy. Values of ADC were regressed against disulphide conformers to determine the presence of linear and quadratic correlations. The ADC of CP in the FeMs ranged from 0.64 to 0.71. Significant (P This study indicated that the ileal digestibility of CP in FeM may be affected by SStgt levels, which can be used as predictors of ADC of CP in FeMs fed to rainbow trout.