Mitchell G, Roberts D G, van Sittert S J
Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA; Centre for Veterinary Wildlife Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa.
Centre for Veterinary Wildlife Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa.
Comp Biochem Physiol A Mol Integr Physiol. 2015 Sep;187:119-29. doi: 10.1016/j.cbpa.2015.05.015. Epub 2015 Jun 2.
We have measured rumen-complex (rumen, reticulum, omasum, abomasum) and intestine (small and large combined) mass in 32 wild giraffes of both sexes with body masses ranging from 289 to 1441 kg, and parotid gland mass, tongue length and mass, masseter and mandible mass in 9 other giraffes ranging in body mass from 181 to 1396 kg. We have estimated metabolic and energy production rates, feed intake and home range size. Interspecific analysis of mature ruminants show that components of the digestive system increase linearly (Mb(1)) or positively allometric (Mb(>1)) with body mass while variables associated with feed intake scale with metabolic rate (Mb(.75)). Conversely, in giraffes ontogenetic increases in rumen-complex mass were negatively allometric (Mb(<1)), and increases in intestine mass, parotid gland mass, masseter mass, and mandible mass were isometric (Mb(1)). The relative masseter muscle mass (0.14% of Mb) and the relative parotid mass (0.03% of Mb) are smaller than in other ruminants. Increases in tongue length scale with head length(0.72) and Mb(.32) and tongue mass with Mb(.69). Absolute mass of the gastrointestinal tract increased throughout growth but its relative mass declined from 20% to 15% of Mb. Rumen-complex fermentation provides ca 43% of daily energy needs, large intestine fermentation 24% and 33% by digestion of soluble carbohydrates, proteins, and lipids. Dry matter intake (kg) was 2.4% of body mass in juveniles and 1.6% in adults. Energy requirements increased from 35 Mj/day to 190 Mj/day. Browse production rate sustains a core home range of 2.2-11.8 km(2).
我们测量了32只体重在289至1441千克之间的雌雄野生长颈鹿的瘤胃复合体（瘤胃、网胃、瓣胃、皱胃）和肠道（小肠和大肠合并）质量，以及另外9只体重在181至1396千克之间的长颈鹿的腮腺质量、舌头长度和质量、咬肌和下颌质量。我们估算了代谢率和能量产生率、采食量和活动范围大小。对成年反刍动物的种间分析表明，消化系统的组成部分随体重呈线性增加（Mb(1)）或正异速生长（Mb(>1)），而与采食量相关的变量则随代谢率呈比例变化（Mb(.75)）。相反，在长颈鹿中，瘤胃复合体质量的个体发育增加呈负异速生长（Mb(<1)），肠道质量、腮腺质量、咬肌质量和下颌质量的增加呈等速生长（Mb(1)）。相对咬肌质量（占体重的0.14%）和相对腮腺质量（占体重的0.03%）比其他反刍动物小。舌头长度的增加与头长(0.72)和Mb(.32)呈比例，舌头质量与Mb(.69)呈比例。胃肠道的绝对质量在整个生长过程中增加，但其相对质量从体重的20%下降到15%。瘤胃复合体发酵提供约43%的每日能量需求，大肠发酵提供24%，通过消化可溶性碳水化合物、蛋白质和脂质提供33%。幼体的干物质摄入量（千克）为体重的2.4%，成体为1.6%。能量需求从35兆焦/天增加到190兆焦/天。嫩枝生产率维持着2.2 - 11.8平方千米的核心活动范围。
