鶏の消化に関する基礎的研究Ⅱ : 筋胃運動に及ぼす砂礫の影響について

　長期間砂礫を給与せずに，ケージ中で飼育した成鶏に粒・粉餌混合飼料を給与し，粒餌，特に大粒玉萄黍の採食不良のものおよび良好のものについてX線観察を行なうとともに，筋胃内に砂礫を全く容しない鶏6羽を選定し，砂礫給与前後の採食状況および筋胃運動をX線連続間接撮影により観察を行ない，砂礫が筋胃運動に及ぼす影響について検討した.その結果は次の通りである.
1) 粒・粉餌混合飼料を給与した際，粒餌の採食が不良の鶏の筋胃内には砂礫は全くないか，存在しでも極く少量に過ぎない.一方，粒餌の採食良好の鶏では，多量の砂礫の滞留を観察した.
2) 砂礫給与後では大粒の飼料を好んで啄食し，粒餌の採食状態は著しく良好となった.筋目内の砂礫は粒餌の採食と何等かの関係があることが推測された.
3) 筋胃に砂礫を容しない胃囊運動は，砂礫給与後に比べ著しく緩慢であり，収縮不全の状態が観取された.
4) 砂礫給与後の筋胃運動は，収縮運動時間が短縮し，また収縮も著しく強烈となり，定型的収縮運動を反復した.その運動経過は，胃囊は運動開始に伴って位置が移動して反転し，次いで球型に収縮した後弛緩期に移る強烈な収縮運動であり，砂礫給与前lこ観察された胃囊異常運動は全く認められない.
　筋胃内の砂礁は胃壁を刺戟して胃囊運動を充進せしめるのに役立つものと判断される.

Experiments on the effects of grit feeding upon the movements of the gizzard and the prehension in the fowl were conducted with hens kept in the cages which had been fed no grit for 5 months before trials. Those were supplied with the experimental feed (grain- mash feed: 6-8, 8-10, 10-20 mesh size grain and mash). Hens showed great individuality in the amount of intake of coarse grain of feed. The gizzard of each hen was respectively observed by means of X-rays.

1) The hens which retained much quantity of grit in the gizzard consumed more amount of coarse grain than hens that retained little (Fig. 3) or no grit (Figs. 1, 2).
2) Six hens which retained no grit in the gizzard were fed grit before supplying with the experimental feed. They consumed much amount of coarse grain. It was suggested that feeding grit affected the amount of intake of coarse grain of feed.
3) The gizzard in which no grit is retained presented slow movements and insufficient contractions (Figs. 5-16, Text-fig. 1). The movements of the gizzard after feeding grit recurred at regular intervals, increasing in frequency and vigor (Figs. 17-20, Figs. 21-24, Text-fig. 1).
4) It was ascertained, therefore, that the grit in the gizzard played a significant role in the gizzard movements as well as in increasing the amount of intake of coarse grain.