ブリ2年魚の配合飼料および生餌主体モイストペレットのタンパク質消化吸収率に及ぼす水温の影響  [in Japanese] Effect of water temperature on the protein digestibility of extruded pellet, single moist pellet and Oregon moist pellet in one-year-old yellowtail  [in Japanese]

ブリ2年魚の各季節におけるエクストルーダーペレット(EP),シングルモイストペレット(SMP)および生餌主体モイストペレット(OMP)のタンパク質消化性を,胃食塊量とタンパク質消化吸収率の食後変化から算出した累積タンパク質消化率により評価した。OMPの累積タンパク質消化率は,季節を問わず86-89%と一定して高かっかが,SMPのそれは9月の84%から3月の69%へと水温低下に伴い著しく低下した。一方,EPの同消化率は12月や3月の低水温期でも83-84%であり,ブリ成魚のEPのタンパク質消化吸収率は比較的高いことが推察された。

Post-feeding changes of apparent protein digestibility (APD) and gastric digesta contents in one-year-old yellowtail Seriola quinqueradiata fed extruded pellets (EP), single moist pellets (SMP), and Oregon moist pellets (OMP) were compared to estimate the protein digestibility (EPD) of those diets between seasons. APD of OMP were constant at 85-90% irrespective of the season and post-feeding time. APD of EP and SMP were 65-80% at the earlier time of post-feeding and 80-90% at the later time. In fish fed SMP, however, APD decreased in low temperature seasons. Gastric evacuation rates were slower in fish fed EP than in fish fed SMP and OMP throughout the seasons. Protein digestibility values estimated based on post-feeding changes of gastric digesta contents and APD were about 86-89% in fish fed OMP during all seasons. Though those values of fish fed EP were relatively high (83-84%) in low-temperature seasons (December and March), those values decreased from 84% to 69% in fish fed SMP as water temperature fell. These results indicate that EPD of SMP is lower than OMP for one-year-old yellowtail during the low-water-temperature periods, while that of EP is identical to OMP.