Changes in incisor dentition of sheep influence biting force
Changes in incisor dentition of sheep influence biting force
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绵羊门牙列变化对咬合力的影响
DOI：
10.1111/j.1365-2494.2004.00428.x
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发表时间：
2004
影响因子：
2.4
通讯作者：
M. Akimoto
中科院分区：
文献类型：
--
作者：
A. Hongo;J. Zhang;Y. Toukura;M. Akimoto
放牧行为的羊，临时门牙的损失后，他们的更换与永久门牙之前，进行了比较后，第一对永久门牙已经完全开发放牧实验，从2001年6月至9月，与三个萨福克阉割公羊，出生于2000年3月下旬。采用人工构建的鸭茅（Dactylisglomerata）人工草地，每隔15 cm分别放置4片（4L）、8片（8L）、12片（12 L）、16片（16 L）和20片（20 L）鸭茅叶片，建立了一种新的咬合量和咬合力测定方法。每组叶片连接到单独的三向测力传感器。
从暂时切牙脱落到恒牙萌出的时间为c。1个月每组叶片的叮咬数量随着叶片密度的增加而增加。每组叶子的叮咬次数在临时门齿的损失后比在永久门齿的损失后高。每口咬的叶片数和干物质（DM）摄入量几乎是永久切牙丢失后的两倍;每咬合力的DM摄入量分别为3.9 - 4.9 mg N-1和1.7 - 2.6 mg N-1。暂时切牙缺失后，4L处理组前向力占总力的0.805，8L ~ 20 L处理组前向力占总力的0.155 ~ 0.317。与此相反，前向力的比例在4L处理中仅占0.292，在8L-20 L处理中占0.026 - 0.163。前向咬合力的角度基本相同（54.7 ~ 56.3 °），后向咬合力的角度基本相同（51.3 ~ 57.3 °）。
The grazing behaviour by sheep, after the loss of the temporary incisors and before their replacement with the permanent incisors, was compared with that after the first pair of permanent incisors had completely developed in grazing experiments, conducted from June to September 2001, with three Suffolk castrated male sheep, born in late-March 2000. A new method was developed to investigate bite mass and bite force, using hand-constructed swards, which were composed of groups of four (4L), eight (8L), twelve (12L), sixteen (16L) and twenty (20L) leaves of cocksfoot (Dactylis glomerata) arranged 15 cm apart. Each group of leaves was attached to a separate three-directional load cell.
The period of time between loss of temporary incisors and the complete eruption of permanent incisors was c. 1 month. The number of bites per group of leaves increased with increasing leaf density. The number of bites per group of leaves was higher after the loss of temporary incisors than with the permanent incisors. The number of leaves per bite and dry-matter (DM) intake per bite were almost twice as great with permanent incisors than after the loss of temporary incisors; DM intakes per bite force were 3·9–4·9 mg N−1 and 1·7–2·6 mg N−1 respectively. After the loss of temporary incisors, the proportion of forward-direction forces accounted for 0·805 of the forces in the 4L treatment and 0·155–0·317 of the forces in the 8L–20L treatments. In contrast, the proportion of forward-direction forces accounted for only 0·292 in the 4L treatment and 0·026–0·163 in the 8L–20L treatments with permanent incisors. The angles of bite forces were almost the same (54·7–56·3°) when sheep used a forward direction, and were 51·3–57·3° when sheep used a backward direction.