Residual feed intake (RFI) is a production efficiency measurement used to account for the growth performance of an individual animal. Less efficient animals have greater levels of oxidative stress. A major source of in vivo oxidative stress is the mitochondria. In this study the protein profile of mitochondria was investigated to determine differences between pigs genetically selected for high and low RFI (less and more efficient, respectively). Mitochondria were isolated from the red and white portions of the semitendinosus muscle (STR and STW respectively), from the longissimus dorsi (LD) muscle, and the liver from pigs (n=24, 12 per line) genetically selected for low or high RFI. Mitochondrial protein differences between lines were determined using 2-D DIGE, and spots were identified using electrospray ionization mass spectroscopy. Heat shock protein (HSP) 60 and HSP70, which have been linked to anti-apoptotic pathways in the mitochondria, were increased in the low RFI line. Endoplasmic reticulum oxidase-1 α (ERO1α) was decreased in LD mitochondria from the low RFI line. The protein profile of mitochondria from the more efficient pigs indicates an increase in anti-oxidant defenses and potential modifications of metabolic pathways leading to oxidative stress, metabolism, and cellular repair.
Biological significance: Observed shifts in the mitochondria protein profile indicate that pigs divergently selected for low residual feed intake (RFI) may be less prone to muscular oxidative stress, and the liver may have a greater metabolic capacity when compared to their less efficient high RFI contemporaries. Both oxidative stress and metabolic capacity are key areas of interest with regard to increasing the efficiency of pork production. Through the use of divergent selection for RFI and investigation of protein profile and other biological differences between RFI lines of pigs, it is possible to determine biological pathways that affect efficiency of food production.
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