Proteomic investigation of brain, liver and intestine in high feed intake and low feed intake Chinook salmon (Oncorhynchus tshawytscha)

In groups of fish, there is often interindividual and intraindividual variation in feed intake. To better understand mechanisms that underpin feed intake, the proteomic profiles of brain, liver, and intestine in high feed intake (HFI) and low feed intake (LFI) Chinook salmon (Oncorhynchus tshawytscha) were investigated. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to quantify 2520 liver, 2783 intestine, and 4052 brain proteins in twenty-seven fish (12 HFI and 15 LFI individuals). Using a population of fish held in tanks, feed intake groups were selected from individual feed intake (%body weight/day (%BW/day)) measured in the meal prior to sampling (HFI: 1.01%BW/day, LFI: 0.41%BW/day). Growth rate and feed conversion ratio were not significantly different between HFI and LFI fish. Protein synthesis in both the intestine and liver of HFI was enriched, indicating increased cellular production in these tissues. In HFI fish, lipid metabolism was the most enriched pathway in the brain. Share of the meal (SM%), calculated as the share of the total feed supplied to the tank, was significantly higher in the HFI (1.59 ± 0.25%) than the LFI (0.72 ± 0.06%) group. This distribution of SM% may suggest that individuals in the HFI and LFI groups were dominant or subordinate, respectively. The LFI group may have suffered from internal or external stressors and accordingly, proteolysis and stress response were activated. This is the first study comparing individual fish with different measured feed intakes at the proteomic level and the outputs provide a preliminary insight into the fundamental molecular landscape of feed intake in Chinook salmon.