Plasma polar lipid profiles of channel catfish with different growth rates  

Increased growth in channel catfish is an economically important trait and has been used as a criterion for the selection and development of brood fish. Selection of channel catfish toward increased growth usually results in the accumulation of large amounts of fats in their abdomen rather than increased muscle mass.  Physiological mechanisms that cause accumulation of fat in the abdomen, as well as regulation of blood lipid profiles and tissue lipid metabolism, have not been investigated in detail. The objective of this study was to examine the lipid blood profile of channel catfish in an attempt to understand functional differences in lipid metabolism from lines of catfish with fast and slow growth.  The plasma polar lipid profile and cholesterol ester were analyzed using tandem mass spectrometry from samples (n=8 per line). The proportion of phosphatidylinositol tended to be greater (p<0.10) in fast growing fish compared to slow growing fish. The proportion of cholesterol ester was also significantly higher (p<0.05) in fast growing fish compared to the slow growing fish.  Analysis of individual lipids revealed that the proportion of 14 lipids were significantly greater (p<0.05 or less) in fast growing fish, whereas the proportion of one lipid tended (p<0.10) to be greater in slow growing fish.  Further studies are required to determine the exact mechanism(s) that caused differences in the plasma lipid profile between catfish with fast and slow growth.