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

反刍动物的上门牙退化。本研究是为了阐明这种退化的上门牙在草觅食的优势，与马相比。实验于1999年7月以3匹纯种马和3头干荷斯坦奶牛为实验对象，2000年7月和8月以3只阉割的萨福克羊为实验对象。1999年施用的牧草品种为多年生黑麦草叶片（PRG）、高羊茅叶片（TF）和芦苇秆（RCG），果园草叶片（OG）施氮量分别为0、10和20 kg/10a。这些草在1999年和2000年分别被固定在15个单向测压台上和5个三向测压台上，并被动物放牧。在预咬伤时，用载荷传感器测定草的抗压强度。饲喂PRG和TF叶片时，牛的预负荷为22.9 ~ 27.9 kg / g DM，马的预负荷为17.7 ~ 23.6 kg / g DM，羊的预负荷为75.2 kg / g DM，羊的预负荷为41.2 kg / g DM。在放牧PRG . More和TF叶片时，牛和马每一口的平均负荷分别为12.5 kg和19.4 kg，羊的平均负荷分别为2.8 ~ 3.3 kg。这些值分别为牛的1.9%、马的3.6%和体重的8.7%。当使用在每个点观察到的最大总负荷时，绵羊向前运动时使用2.01-2.26 kg的总负荷，向后运动时使用2.63-2.65 kg的总负荷。结果表明，绵羊在向前运动时，下门牙能够有效地切断草地，从而降低总负荷。牛用舌头缠绕草，拉草来催情。在RCG硬秆与PRG/TF软秆混合的条件下，奶牛可以选择性剪切没有上前齿的软叶，因为硬秆具有较高的抗拉强度。软管使用强壮，灵活和敏感的上唇收集草，并通过上下门牙将其剪掉。吃草时，马把叶子和茎都剪了。因此，提出了反刍动物觅食的“梳出”策略，以避开硬秆。这个词来源于梳理头发的同样行为。结果将很快公布。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