In central-place foragers the breeding cycle is often the period with the highest energy cost, where dietary and stored lipids play a key role. Lipids are mobilized through blood lipoproteins providing fuel to tissues. Thus, the use of food and endogenous resources with high-energy fats is important to sustain individuals’ nutritional demands. To evaluate the physiological components associated to energetic demands and their variation regarding life history processes, we analysed the plasma circulating lipoprotein levels, the lipid classes and fatty acid (FA) composition in Brown Skua (Stercorarius antarcticus lonnbergi) in breeding stages with different energy requirements: incubation (In), early rearing (Er) and late rearing (Lr). We expected to find differences according to the energy demands of each stage and the sex. The level of Very Low Density lipoproteins was affected by the sex and the breeding stage, whereas Low Density lipoproteins only by the stage. Total plasma lipid content and circulating lipid classes were invariant among the stages studied; however, differences in total plasma FA and monounsaturated FA (oleic and nervonic) abundances were observed among stages. Besides, a decrease in the n-3:n-6 ratio was observed towards the Lr stage. The differences found in lipoproteins may be linked to changes in the energy demands throughout the breeding period. Moreover, the variation observed in FA abundance and n-3:n-6 ratio may be related to a preferential mobilization of FA from stores as fuel or, possibly, to a differential use of the available food resources.

在中部觅食者中，繁殖周期通常是能量成本最高的时期，其中饮食和储存的脂质起关键作用。脂质通过血液脂蛋白动员，为组织提供燃料。因此，使用食物和具有高能量脂肪的内源性资源对于维持个人的营养需求非常重要。为了评估与能量需求有关的生理成分及其在生活史过程中的变化，我们分析了棕贼鸥（Stercorarius antarcticus lonnbergi）的血浆循环脂蛋白水平，脂质类别和脂肪酸（FA）组成）处于不同能量需求的育种阶段：孵化（In），早育（Er）和晚育（Lr）。我们希望根据每个阶段和性别的能量需求找到差异。低密度脂蛋白的水平受性别和繁殖阶段的影响，而低密度脂蛋白的水平仅受该阶段的影响。在研究的各个阶段中，血浆总脂质含量和循环脂质类别不变。然而，在各阶段中观察到总血浆FA和单不饱和FA（油酸和神经）丰度的差异。此外，在Lr阶段观察到n-3：n-6比率降低。脂蛋白中的差异可能与整个繁殖期间能量需求的变化有关。此外，在FA丰度和n-3中观察到的变化：