Investigating the effects of a novel poultry protein dietary inclusion for atlantic salmon on gut transit rate

Temperature and resource availability pose an ongoing threat to the Tasmanian Atlantic salmon (Salmo salar) aquaculture industry. The rising cost of traditionally used fish meal has forced the sector to utilise novel protein by-product sources such as poultry protein concentrate. However, alternative dietary formulations can effect digestive processes. Additionally, prolonged exposure to sub-optimally high-water temperature is known to effect gut transit rate and limits the potential for nutrient uptake. The combined effect of temperature and the inclusion of poultry protein concentrate on the gut transit rate of Atlantic salmon remains unexplored. As such, this study aims to quantify the influence of water temperature and poultry protein concentrate on gut transit rate in Atlantic salmon. This study assessed gut transit rate in three regions of the gastro-intestinal tract of post-smolt Atlantic salmon under at 15 oC and 20 oC. Fish were fed one of three dietary treatments containing varying levels of poultry protein concentrate and an inert silica (ballotini) bead inclusion. Gut transit rate was assessed by determining the relative bead and mean total bead density of the tract for 48 hours post-feeding. Temperature was found to have a significant effect on the relative bead density of all gastro-intestinal tract regions. Whilst some statistically significant relationships were observed between poultry protein concentrate inclusion and relative bead density, visual observations of the data found no discernible patterns. As such, additional investigation into the integration of poultry protein concentrate is recommended. Additionally, it is suggested that future research be conducted to gain a broader understanding of digestive processes, mainly gut transit rate. This study will assist with the continued efforts by the aquaculture industry to meet increasing demand for nutritional seafood products in a sustainable manner despite the projected climate change and the adverse conditions encountered in the Southern Hemisphere.