Nofs S A, Dierenfeld E S, Backus R C
Nashville Zoo at Grassmere, Nashville, TN, USA.
Ellen S. Dierenfeld, LLC, St. Louis, MO, USA.
J Anim Physiol Anim Nutr (Berl). 2018 Feb;102(1):e316-e325. doi: 10.1111/jpn.12748. Epub 2017 Jun 14.
The giant anteater (Mymercophaga tridactyla) is a highly specialized insectivore for which nutrient requirements are not clearly established, making diet formulation challenging for this species. Multiple clinical reports suggest anteaters have an obligate dietary taurine (TAU) requirement. Sulphur amino acid (SAA) metabolism in adult anteaters was evaluated using noninvasive methods to measure TAU synthesis potential from dietary methionine (MET) and a basal diet containing on a dry matter (DM) basis 1.7 mg TAU/kg DM and 6.9 g MET/kg DM. Urinary equilibrium times for TAU excretion were determined by feeding the basal diet with or without 1.5 g/kg DM supplemental TAU (crossover design; n = 4). Effects of supplemental dietary TAU (1.7, 2.0, 2.4, 2.7, 3.0, 3.3 g/kg DM) or MET (6.9, 9.0, 11.2 g/kg DM) on urinary TAU were evaluated (randomized block trials; n = 5 or 4 respectively). All urinary values (TAU, MET, unbound inorganic sulphate) were normalized to creatinine (CRT). Results indicate urinary TAU equilibrium in anteaters requires at least 2 weeks of feeding. Urinary ratio of TAU to CRT (TAU:CRT) increased as dietary TAU content increased from 1.7 to 3.0 g/kg DM, consistent with renal homoeostatic modulation of TAU excretion. Our data indicate that TAU needs were met by TAU in the basal diet or by de novo synthesis. Supplemental MET resulted in ~five- to eightfold increases in urinary TAU:CRT excretion, further supporting existence of mechanisms for TAU synthesis from dietary SAA in anteaters. Adult anteaters appear able to synthesize TAU when diets contain adequate SAA, but dietary TAU may be critical if protein intakes are low or of poor quality. This study may provide guidance on choice of domestic canids vs. felids as suitable physiologic models for improved nutrition in giant anteaters, and also outlines a noninvasive method for assessing TAU status/metabolism that may be useful across species.
大食蚁兽（Myrmecophaga tridactyla）是一种高度特化的食虫动物，其营养需求尚未明确确定，这使得为该物种制定饮食配方具有挑战性。多项临床报告表明，食蚁兽对牛磺酸（TAU）有绝对的饮食需求。使用非侵入性方法评估成年食蚁兽的硫氨基酸（SAA）代谢，以测量从膳食蛋氨酸（MET）和基础日粮（以干物质（DM）计，含1.7毫克TAU/千克DM和6.9克MET/千克DM）中合成TAU的潜力。通过给基础日粮添加或不添加1.5克/千克DM补充TAU来确定TAU排泄的尿平衡时间（交叉设计；n = 4）。评估补充膳食TAU（1.7、2.0、2.4、2.7、3.0、3.3克/千克DM）或MET（6.9、9.0、11.2克/千克DM）对尿TAU的影响（随机区组试验；分别为n = 5或4）。所有尿液值（TAU、MET、未结合的无机硫酸盐）均以肌酐（CRT）进行标准化。结果表明，食蚁兽的尿TAU平衡需要至少2周的喂食时间。随着膳食TAU含量从1.7克/千克DM增加到3.0克/千克DM，尿TAU与CRT的比值（TAU:CRT）增加，这与TAU排泄的肾脏稳态调节一致。我们的数据表明，基础日粮中的TAU或从头合成可满足TAU需求。补充MET导致尿TAU:CRT排泄增加约五至八倍，进一步支持了食蚁兽从膳食SAA合成TAU的机制的存在。当饮食中含有足够的SAA时，成年食蚁兽似乎能够合成TAU，但如果蛋白质摄入量低或质量差，膳食TAU可能至关重要。本研究可为选择家犬与家猫作为改善大食蚁兽营养的合适生理模型提供指导，还概述了一种评估TAU状态/代谢的非侵入性方法，该方法可能对跨物种有用。
