Effect of fractionation on nutritional value of wheat distillers grains for rainbow trout (Oncorhynchus mykiss)
Reveco Urzúa, Felipe Eduardo
In this study, the nutritional value of wheat distillers grains and the effect of further processing of these products on their nutritional value for rainbow trout were investigated in five experiments. In experiments 1 and 2, wheat distillers grains with solubles (WDDGS) was fractionated using grinding, sieving and elutriation sequentially. Apparent digestibility coefficients (ADC) of dry matter (DM), gross energy (GE), acid ether extract (AEE), ash and amino acids (AA) did not differ between the original WDDGS and the WDDGS protein concentrate (P > 0.05). However, the ADC of crude protein (CP) was significantly higher for WDDGS protein concentrate (88.0 %) than the original WDDGS (84.9 %) (P < 0.05). In experiments 3 and 4, the effect of aqueous fractionation on nutritional composition of wheat wet distillers grains (WWDG) from two local ethanol plants (plant 1 and plant 2) was evaluated. Aqueous fractionation increased levels of CP and GE in the processed WWDG from both plants. Fractionation significantly increased the ADC of DM, GE and AEE (P < 0.05). In contrast, protein digestibility was not influenced by the plant or the processing method (P > 0.10). In experiment 5, a 56 d growth trial was performed to determine the effect feeding the aqueous fractionated WWDG to rainbow trout on growth performance. Rainbow trout (n=22/ tank; body weight 136 g and 3 tanks/ treatment) were fed diets containing 0, 75, 150, 225 and 300 g kg-1 of the processed WWDG from plant 2. There were no significant linear or quadratic relationships between inclusion rate and specific growth rate (SGR), average daily gain (ADG) or feed to gain ratios (feed:gain). However, there was a significant negative linear relationship between inclusion rate and average daily feed intake (ADFI) (P < 0.05). The results of these studies suggest that both dry and aqueous fractionation are suitable methods to produce protein concentrates from wheat distillers grains but that the aqueous fractionation process was more effective in improving nutrient composition and increasing digestibility.
DegreeMaster of Science (M.Sc.)
DepartmentAnimal and Poultry Science
ProgramAnimal and Poultry Science
SupervisorDrew, Murray D.
CommitteeLaarveld, Bernard; Zello, Gordon; Reaney, Martin; Van Kessel, Andrew
Copyright DateJuly 2010