GASTROINTESTINAL TRANSIT AND LIPID ASSIMILATION EFFICIENCIES IN 3 SPECIES OF SUB-ANTARCTIC SEABIRD

Using tritium‐labeled glycerol triether ([3H] GTE) as a nonabsorbable lipid‐phase marker and tritium‐labeled polyethylene glycol 4000 ([3H] PEG) as a nonabsorbable aqueous‐phase marker, we examined gastrointestinal transit of homogenized Antarctic krill (Euphausia superba) meals fed to white‐chinned petrels (Procellaria aequinoctialis), sooty albatrosses (Phoebetria fusca), and rockhopper penguins (Eudyptes chrysocome). The aqueous‐phase marker was excreted significantly more rapidly than was the lipid‐phase marker by the two procellariiform species, whereas no differential transit rates for the two markers were observed in the penguins. Aqueous‐phase marker recoveries after 48 hours from the three species were statistically indistinguishable (78.6% ± 3.7%, n = 5; 71.9% ± 11.3%, n = 7; and 77.0% ± 9.4%, n = 4, respectively). Lipid‐phase marker recovery from the penguins after 48 hours was nearly complete (83.8% ± 19.3%, n = 5, and 92.7% ± 14.8%, n = 5, for two dietary lipid supplements, see below), whereas less than 50% of the original dose of lipid marker was recovered from the two procellariiform species. Substantial lipid‐phase marker was recovered as stomach oils from the procellariiforms. Assimilation efficiencies of [1‐14C] tripalmitin dissolved in wax ester and [1‐14C] cetyl oleate dissolved in triglyceride were compared for the same three seabirds by comparing 3H/14C ratios in the food and feces of birds simultaneously fed one of the above 14C‐labeled lipids, and the non‐metabolizable marker [3H] GTE. The petrel and the albatross showed high assimilation efficiencies (> 80%) of both 14C‐labeled neutral lipids. Rockhopper penguins consistently excreted [3H] GTE faster than did adult sooty albatrosses and were significantly less efficient at assimilating both neutral lipids (62% and 45% respectively). Sooty albatross fledglings excreted lipids significantly more slowly than did adults of this species, but lipid assimilation efficiencies did not differ with age. Gut measurements showed that the intestine of the rockhopper penguin was three and six times as long as those of the sooty albatross and white‐chinned petrel respectively. Copyright © 1990 Wiley‐Liss, Inc., A Wiley Company