Seasonal, Age, and Sex-Related Variation in Fatty-Acid Composition of Depot Fat in Relation to Migration in Western Sandpipers

SUMMARYThe fatty acid composition of muscle membrane phospholipids and fat stores may affect migration performance in birds. The purpose of this study was to investigate seasonal changes in the fatty acid composition of (1) pectoralis muscle phospholipids, (2) intramuscular triglyceride stores and (3) adipose tissue triglycerides in free-living white-throated sparrows (Zonotrichia albicollis). During migratory seasons there was an increase in the n-6:n-3 ratio of muscle membrane phospholipid fatty acids without a change in the proportion of unsaturated fatty acids. This change was driven mainly by an increase in the proportion of 18:2n-6 and a decrease in the proportion of 22:6n-3. An increase in the proportion of 18:2n-6 was also observed in the intramuscular and adipose tissue triglyceride stores during the migratory seasons. These increases in 18:2n-6 were offset by a decrease in 16:0; resulting in an elevated proportion of unsaturated fatty acids and elevated double bond index in both fat stores of migrants. The elevated levels of 18:2n-6 in migrant fat stores indicates a high dietary component of this fatty acid, as whitethroated sparrows feed mainly on tree seeds and some insects during migration and may not have access to a diet high in n-3 fatty acids. We suspect that elevated dietary levels of 18:2n-6 also caused the observed increases in the proportion of this fatty acid in muscle phospholipids. Overall, we conclude that seasonal changes in adipose and muscle fatty acid composition are likely attributable to diet more than other factors such as migratory exercise or mitochondrial density.

Section: Introductionmentioning

confidence: 99%

Fatty acid composition of pectoralis muscle membrane, intramuscular fat stores and adipose tissue of migrant and wintering white-throated sparrows (Zonotrichia albicollis)

Klaiman

Price

Guglielmo

2009

“…Although few studies document fatty acid composition of fat stores in birds during migration, evidence to date shows that the majority of lipids in migrating birds comprise 16-or 18-carbon fatty acids, and unsaturated fatty acids (mostly 16:1, 18:1, 18:2) usually predominate over saturated fatty acids (mostly 16:0 and 18:0;Blem, 1976;Conway et al, 1994;Egeler and Williams, 2000). Whether a certain fatty acid Most migrating birds accumulate lipid stores as their primary source of energy for fueling long distance flights.…”

mentioning

confidence: 99%

Effect of dietary fatty acid composition on depot fat and exercise performance in a migrating songbird, the red-eyed vireo

Pierce

McWilliams

O’Connor

et al. 2005

106

SUMMARY Most migrating birds accumulate lipid stores as their primary source of energy for fueling long distance flights. Lipid stores of birds during migration are composed of mostly unsaturated fatty acids; whether such a fatty acid composition enhances exercise performance of birds is unknown. We tested this hypothesis by measuring metabolic rate at rest and during intense exercise in two groups of red-eyed vireos, a long-distance migratory passerine, fed either a diet containing 82% unsaturated fat (82%U), or one containing 58% unsaturated fat (58%U). Vireos fed the 82%U diet had fat stores containing (77%) unsaturated fatty acids, whereas vireos fed the 58% U diet had fat stores containing less (66%) unsaturated fatty acids. Blood metabolites measured prior to and immediately following exercise confirmed that vireos were metabolizing endogenous fat during intense exercise. Mass-specific resting metabolic rate (RMR) was similar for vireos fed the 58%U diet (2.75±0.32 ml O2 g–1h–1) and for vireos fed the 82%U diet (2.30±0.30 ml O2 g–1 h–1). However,mass-specific peak metabolic rate (MRpeak) was 25% higher in vireos fed the 58%U diet (28.55±1.47 ml O2 g–1h–1) than in vireos fed the 82%U diet (21.50±1.76 ml O2 g–1 h–1). Such whole-animal energetic effects of fatty acid composition of birds suggest that the energetic cost of migration in birds may be affected by the fatty acid composition of the diet.

“…These are accompanied by changes in physiology and nutrient metabolism that maximize lipid storage ahead of the journey and promote its efficient utilization for energy during the flight (Piersma and Lindström, 1997;McWilliams et al, 2004). Despite the wide diversity of food resources and habits, accumulated fat in migratory birds displays a highly conserved mixture of saturated and monounsaturated 16-and 18-carbon FA (Egeler and Williams, 2000;McWilliams et al, 2004;Pierce et al, 2004;Pierce and McWilliams, 2005). In the present study, the average chemical structure estimated by 1 H NMR analysis captured this profile.…”

Section: Discussionmentioning

confidence: 99%

“…Preference for lipid-rich diets has been frequently documented in migratory birds (Bairlein and Gwinner, 1994;Egeler and Williams, 2000;Pierce and McWilliams, 2005;Ben-Hamo et al, 2011) and partially drives the composition of subcutaneous fat that is ultimately a determinant for flight performance. Consequently, it has also been suggested that for migrating birds such as Z. albicollis, there is some degree of selectivity over which FA are released during lipolysis of stored fat (Price and Guglielmo, 2009).…”

Section: Discussionmentioning

confidence: 99%

“…Consequently, it has also been suggested that for migrating birds such as Z. albicollis, there is some degree of selectivity over which FA are released during lipolysis of stored fat (Price and Guglielmo, 2009). In fact, several bird species increase the proportion of UFA in their fat stores in the period prior to migration (Egeler and Williams, 2000;Pierce and McWilliams, 2005), a feature considered adaptive for and also potentially influencing spatial packing, fluidity, ion-leak, signalling pathways and integral protein function of membranes (Guglielmo, 2010;Pierce and McWilliams, 2014). However, in the case of lipidpoor diets, the subcutaneous accumulation of certain UFA such as the n-3 may pose as a physiological challenge, as observed in the rice-fed birds.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Metabolic plasticity for subcutaneous fat accumulation in a long distance migratory bird traced by 2H2O

Viegas

Araújo

Rocha

et al. 2017

The migrant black-tailed godwit (Limosa limosa) traditionally used natural wetlands in the Iberian Peninsula to prepare for migratory flights by feeding mainly in estuaries. In recent decades, this species has become increasingly dependent on rice fields, thereby relying on a plant-based diet for fuelling. Dietary fatty acids (FA) seem to be determinant to the composition of accumulated subcutaneous fat in migratory birds. It is still unclear whether metabolic plasticity allows for modification and/or synthesis of FA, contributing to a lipid profile that enables a successful migratory performance. Deuterated water was administered to captive black-tailed godwits submitted to two diets (fly larvae versus rice) and the incorporation of deuterium ( 2 H) into subcutaneous triglycerides was analyzed by NMR. A recently developed localized biopsy method for sampling subcutaneous fat was employed with later successful release of all birds into the wild. The average chemical structure reflected mostly a mixture of saturated and monounsaturated 16-and 18-carbon FA, a profile frequently found in migrant birds. Significantly higher levels of polyunsaturated FA, as well as detectable levels of n-3 FA, were observed in fly-larvae-fed birds. Excess 2 H-enrichments in FA revealed significantly higher rates of fractional de novo lipogenesis and FA desaturation capacity in rice-fed birds. This novel and nonlethal tracer method revealed the capacity of this species to alter its lipid metabolism to compensate for a poorer dietary lipid contribution. Because of its versatility, adapting this method to other scenarios and/or other migratory species is considered feasible and costeffective.