Date of Award


Degree Type


Degree Name

Doctor of Philosophy




Christopher Guglielmo

Second Advisor

Jim Staples

Third Advisor

Louise Milligan


Migratory birds use fat nearly exclusively to fuel their long distance movements. Little is known about how different types of fat affect their migratory performance, although dietary fats have been hypothesized to affect exercise through their roles as both oxidative substrates and membrane components. This thesis investigated the effects of fatty acids on avian flight performance and evaluated these two hypothesized mechanisms. I first investigated the selective mobilization of fatty acids from avian adipocytes. Unsaturated fatty acids and short chain fatty acids were most readily mobilized from avian adipocytes, indicating they may be important in increasing maximal metabolic rates. Further, this pattern did not change with migratory condition. I also investigated the effect of migratory condition and exercise on muscle phospholipid composition. Migratory disposition itself did not induce any endogenous changes to muscle phospholipid composition in preparation for migration, although exercise did have an effect on muscle phospholipids. Next, I demonstrated that birds fed a high co6 fatty acid diet achieved higher peak metabolic rates than those fed a high co3 diet. Further, I used a dietary manipulation to independently alter adipose triacylglycerol stores and muscle phospholipid composition. This experiment demonstrated that phospholipid composition does not drive exercise performance differences, but that triacylglycerol composition might be responsible for increased peak metabolic rate in birds fed the high ©6 diet. I also investigated the selectivity of the mitochondrial membrane fatty acid transporter carnitine palmitoyl transferase, and demonstrated that its activity was highest with shorter and polyunsaturated fatty acyl CoA substrates. Overall, maximal exercise in performance in birds may be affected by stored triacylglycerol composition due to selectivity of the fatty acid transport system, but does not appear to be affected by muscle phospholipid composition. Finally, I developed a theoretical framework for the study of avian fat composition that focuses on the tradeoffs between energy storage and transport of fatty acids.



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