Assimilation Efficiency and Growth of Rhinoceros Auklet Chicks Fed With Japanese Sand Lance and Krill

27 Mar Assimilation Efficiency and Growth of Rhinoceros Auklet Chicks Fed With Japanese Sand Lance and Krill

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Abstract

ウトウCerorhinca monocerata雛にイカナゴAmmodytes perso tusとナンキョクオキアミEuphausia superbaを給餌し，その消化率と成長を調べた．イカナゴについては，雛に1日あたり湿重量で79.4±3.1 gwet/d（平均±標準偏差）与え，497.2±14.9 kJのエネルギー価，4.3±0.2 gの脂質，12.3±0.5 gのタンパク質を含んでいた．オキアミについては，雛に1日あたり湿重量で129.3±2.7 gwet/dを与え，746.8±15.5 kJのエネルギー価，3.1±0.1 gの脂質，23.3±0.5 gのタンパク質を含んでいた．窒素補正で修正した消化率，見かけの代謝エネルギー率はイカナゴを与えた雛で82.8±0.5％で，オキアミを与えた雛の76.6±0.6％より有意に高かった．実験期間中のイカナゴ雛とオキアミ雛の成長速度は11.0±4.7（g/d, n＝12）と9.7±2.7（g/d, n＝14）であった．オキアミを与えられた雛の体重増加は，日齢の効果を考慮すると，イカナゴを与えられた雛の値よりも有意に低かった．イカナゴに比べ脂質の少ないオキアミは雛の成長には不適当な餌かもしれない

English Abstract

The assimilation efficiency and growth of Rhinoceros Auklet Cerorhinca monocerata chicks (30–35 age of days) fed with Japanese Sand Lance Ammodytes perso tus 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 i dequate for chick growth of the auklets due to the poorer lipid content, compared with sand lance.