重水希釈法によるイヌの体脂肪率測定にあたって,投与された重水が体内で平衡に達する時間および体内から排出される時間を確認するために,ビーグルに体重kgあたり0.2mlの重水分を静脈内投与し,血漿重水濃度を経時的に測定した。その結果,血漿重水濃度は投与15分以降180分まで一定した高値を示した。また3日後にはピーク値の64%,7日後には26%まで減少し,49日後には投与前値に復した。以上のことから体脂肪率測定に重水希釈法を用いるにあたっては,無麻酔のイヌでは重水分投与15分以降180分以内の血漿重水濃度を用いれば良いこと,連続して測定する際は7週間の間隔を空ける必要があることが示された。重水希釈法により得られた供試犬の体脂肪率は各々18,23および39%で,それぞれのBCS3,3および4とも矛盾無く照応した。またイヌにおける体水分の生物学的半減期は約4日と考えられた。

抄録全体を表示

Four mature Beagles weighing 15 kg on average were used to determine digestible energy (DE) and digestible crude protein (DCP) contents of 20 samples of 17 feedstuffs, and nitrogencorrected metabolizable energy (MEn) was individually estimated with an equation [MEn = -DE1.25DCP], which was proposed by our previous work. Digestibility of crude protein, acid ether extract, and nitrogen-free extract varied in a wide range among feedstuffs, even among three samples of feather meal. The digestibility of crude protein, acid ether extract, and nitrogen-free extract as well as the DE content showed a significant negative correlation with crude fiber contents among 13 samples of 12 feedstuffs other than animal by-product feedstuffs and cornstarch. The system proposed by NRC to evaluate dietary metabolizable energy (ME) in dogs tended to underestimate the energy value of some feedstuffs, especially low-fiber starchy feedstuffs such as cereals and cornstarch, but tended to overestimate other feedstuffs, especially high-fiber feedstuffs such as wheat bran and rice bran. This was due to the fixed digestibility of proximate components adopted by NRC. Present results suggest that the MEn obtained by applying actually determined DE and DCP to the above equation would be more reliable than the ME values estimated according to the NRC system.

抄録全体を表示