Abstract
The assimilation efficiency and growth of Rhinoceros Auklet Cerorhinca monocerata chicks (30-35 age of days) fed with Japanese Sand Lance Ammodytes personatus and Antarctic Krill Euphausia superba were investigated. Chicks were fed 79.4 ± 3.1 gwet /d (mean ± SD) of sand lance, which included 497.2 ± 14.9 kJ energy, 4.3 ± 0.2 g lipid, and 12.3 ± 0.5 g protein. Chicks were fed 129.3 ± 2.7 gwet /d krill, which include 746.8 ±15.5 kJ energy, 3.1 ±0.1 g lipid, and 23.3 ±0.5 g protein. The assimilation efficiency (corrected with nitrogen retention) of the sand lance-fed chicks (82.8 ±0.5%) was significantly higher than the krill-fed chicks (76.6 ±0.6%). During the experiment, daily mass increments of the sand lance-fed chicks were 11.0 ±4.7 (g/d, n=12) and of the krill-fed chicks 9.7 ±2.7 (g/d, n=14). Sand lance-fed chicks gained body mass significantly faster than did krill-fed chicks after controlling for the significant age effect. Krill may be inadequate for chick growth of the auklets due to the poorer lipid content, compared with sand lance.
