Study on break-down energy of grasses used at foraging of grazing animals -comparison of cattle to horse

反刍动物会使上门牙退化。这项研究是为了阐明与马相比，上门牙在草食时的这种退化的优势。这些试验是在1999年7月用三匹纯种马和三头干荷斯坦奶牛，以及在2000年7月和8月用三只去势的萨福克羊进行的。1999年采用多年生黑麦草叶(PRG)、高羊茅叶(Tf)和芦竹(RCG)，果草叶(OG)施氮量分别为0、10和20 kg/10a。1999年将这些牧草固定在15个单向测力仪上，2000年将其固定在5个三向测力仪上，并进行动物放牧。在抓取咬合时，用测力仪测定牧草的分解强度。饲喂PRG和TF叶时，奶牛每1g DM的预负荷为22.9~27.9 kg，马为17.7~23.6 kg，绵羊为75.2 kg，高叶密度时为41.2 kg。在PRG…放牧时，每咬一口的平均负荷量，奶牛为12.5公斤，马为19.4公斤和Tf叶较多，绵羊2.8-3.3公斤。牛为1.9%，马为3.6%，体重为8.7%。按各点观测到的最大总负荷值计算，绵羊向前运动总载荷为2.01~2.26 kg，向下运动总载荷为2.63~2.65 kg。这一结果表明，绵羊在向前移动时可以通过较低的门牙有效地割草，从而获得较低的总负荷量。在RCG硬秆和软质PRG/TF叶的混合物中，由于硬秆的抗拉强度较高，奶牛可以选择性地剪除软叶而不需要上前缘。Hoese用结实、移动和敏感的上嘴唇收集青草，并用上下门牙将其剪掉。在放牧时，马把树叶和秸秆剪在一起。为此，提出了反刍动物觅食的“梳出式”策略，以避免硬秆。这个词来自于梳理头发的相同行为。结果很快就会公布。较少

Ruminants degenerate upper front teeth. This study was carried out in order to clarify an advantage of this degeneration of upper front teeth at grass foraging, compared with horse. The experiments were carried out using three thoroughbred horses and three cows of dry Holstein in July 1999, and three castrated Suffolk sheep in July and August 2000. Grass species used were perennial ryegrass leaves (PRG), tall fesue leaves (TF) and reedcanary culms (RCG) in 1999, and orchardgrass leaves (OG) applied with 0, 10 and 20 kg/10a of nitrogen. These grasses were fixed on 15 one-way loadcells in 1999 and 5 three-way loadcells in 2000, and were grazed by animals. At prehending bite, break-down strength of grasses was measured by loadcells.Prehending load per 1g DM was 22.9-27.9 kg in cow 17.7-23.6 kg in horse when PRG and TF leaves were given, and 75.2 kg at low leaf density and 41.2 kg at high leaf density in sheep. Mean load per 1 bite was 12.5 kg in cow and 19.4 kg in horse at grazing of PRG … More and TF leaves, and 2.8-3.3 kg in sheep. These values were correspondent to 1.9% in cow, 3.6% in horse and 8.7% of body weights. Sheep used 2.01-2.26 kg of total load at forward movement and 2.63-2.65 kg kg of total load at buckward movement when maximum values of total loads observed at each point were used. This result suggests that sheep can effectively sever grasses by a lower front teeth at forward movement, resulted in lower total load.Cow wrap their tongues around grass and pull to pregend it. In a mixture of hard culms of RCG and soft PRG/TF leaves, cow could selectively shear soft leaves without upper front theeth, because hard culms were avoided for their higher tensile strength. Hoese use strong, mobile and sensitive upper lip to collect grass and shear off it by both upper and lower front teeth. At grazing, horse sheared both leaves and culms together. Therefore, "comb-out" strategy of ruminant foraging is made a proposal concerning an avoidance of hard culms. This term was brought from the same behavior of combing out a hair. The result will be published soon. Less