Effects of piscivory on the fatty acid profiles and antioxidants of avian yolk: studies on eggs of the gannet, skua, pelican and cormorant

Abstract

Piscivorous birds consume diets which are rich in highly-polyunsaturated n-3 fatty acids; these play vital roles in embryonic development but are very susceptible to oxidative damage. The effects of such diets on the fatty acid composition and antioxidant content of the yolk were investigated in the northern gannet Morus bassanus, the great skua Catharacta skua, the American white pelican Pelecanus erythrorhynchos and the double-crested cormorant Phalacrocorax auritus. The phospholipid fraction of the eggs of these four species contained high proportions of the n-3 fatty acid, docosahexaenoic acid, which formed 7.5±11.3% (w/w) of the fatty acids of this fraction. The presence of eicosapentaenoic and docosapentaenoic acids also contributed to the total n-3 content of the phospholipid. The n-6 polyunsaturate, arachidonic acid, formed between 8% and 19% (w/w) of the phospholipid fatty acids. For the pelican and cormorant, this is consistent with the consumption of freshwater ®shes in which arachidonic acid may be a signi®cant acyl constituent. This ®nding is, however, more dif®cult to explain for the gannet and skua which largely consume marine ®sh with a low arachidonic acid content. The yolks of all four species contained relatively high concentrations of vitamin E (90.2±302.3 mg g 71 wet yolk) which was mainly present as a-tocopherol. The eggs of the pelican and cormorant were especially enriched in carotenoids (150.9 and 115.7 mg g 71 wet yolk, respectively).

Physiological constraints and the influence of diet on fatty acids in the yolk of gentoo penguins, Pygoscelis papua

“…The dominance of these three FA in yolk lipids agrees with their similar abundances found in the blood FA composition of Adélie penguins during yolk formation (Tierney et al 2008). The FA 16:0, 18:1n-9 and to a lesser degree 18:0 are common and often dominate constituents of yolk FA in other piscivorous birds as well as granivorous, herbivorous and carnivorous species (Speake et al 1998(Speake et al , 1999bSurai et al 2001;Barton et al 2002). In addition to contributing to energetic demands through non-specific b-oxidation, 16:0, 18:0 and 18:1n-9 can be important during embryonic development (Groscolas et al 2003).…”

“…Similar to other marine birds, penguin diets are rich in highly-polyunsaturated n-3 FA, but often contain only trace amounts of n-6 FA (Speake et al 1999a;Surai et al 2001). However, the diets of these three penguin species differ to some degree and comprise varying amounts of krill, fish and squid (Offredo and Ridoux 1986;Raclot et al 1998;Miller et al 2010).…”

NATURAL ANTIOXIDANTS IN HENS' EMBRYOGENESIS AND ANTISTRESS DEFENCE IN POSTNATAL DEVELOPMENT (review)

“…Many wild bird species can accumulate in the egg yolk great amounts of carotenoids (50-10 times more than in edible chicken eggs) (30,39). Eggs from the hens fed a maize-based diet were found to contain at least twice more carotenoids than eggs from the hens given a wheat-barley diet (44).…”

“…In a hatchling this is mainly provided by high tissue levels of natural antioxidants, especially vitamin E (27,29), and sometimes (in wild birds), carotenoids (30)(31)(32)(33)(34). In the first 10 days after hatching, the levels of vitamin E and carotenoids in the liver tissue reduce by 20 times; this occurs in chickens, as well as in turkeys, ducks, and geese (23).…”

“…Vitamin E can easily transfer to the egg yolk and then -to the developing embryo (29). Eggs of many wild bird species have a relatively high content of this vitamin (13,30,39). Accumulation of vitamin E in eggs is species-specific: feeding an equal dietary dose of vitamin E contributes to the higher level in chicken egg compared with eggs of turkeys, geese, or ducks (23).…”