Riek Alexander, Van Der Sluijs Leendert, Gerken Martina
Institute of Animal Breeding and Genetics, University of Goettingen, Goettingen, Germany.
J Exp Zool A Ecol Genet Physiol. 2007 Dec 1;307(12):667-75. doi: 10.1002/jez.a.419.
Energy expenditure and water flux were measured in free-ranging alpacas Lama pacos, a South American camelid, on natural pastures of the Peruvian Andes (altitude: 4,400 m above sea level). Water influx rate (WIR) was estimated in 16 males (age 2 years, weight 48.5+/-8.6 kg) labelled with 2H. In addition, the field metabolic rate (FMR) was measured in four of these animals labelled with both an oxygen (18O) and a hydrogen (2H) isotope. The WIR averaged 3.62 L H2O/day and the mean total body water 33.1 kg, equal to 68.2% of body weight (BW). The FMR of the four doubly labelled animals was 14.05 MJ/day. New allometric equations were calculated describing the relationships between WIR or FMR and BW, respectively, including published data on ruminants and the present alpaca results. The regression equation indicates that daily WIR scales to a similar metabolic size (kilograms of BW(0.94)) in alpacas than in wild or domesticated ruminants and camelids originating from arid and semiarid habitats. The resulting regression equation for FMR explained over 99% of the variation and corresponded to the function FMR (kilojoules per day)=1079 (kilograms of BW0.668) (n=5, r2=0.995, P<0.001). The FMR measured in this study, the first reported for a South American camelid species, suggests that free-ranging alpacas have similar energy expenditures on a metabolic weight basis as other wild ruminants living under harsh climatic conditions.
在秘鲁安第斯山脉（海拔4400米）的天然牧场上，对自由放养的南美骆驼科动物羊驼（Lama pacos）的能量消耗和水通量进行了测量。对16只2岁、体重48.5±8.6千克的雄性羊驼标记2H后，估算了其水流入率（WIR）。此外，对其中4只同时标记氧（18O）和氢（2H）同位素的动物测量了野外代谢率（FMR）。WIR平均为3.62升水/天，平均总体水为33.1千克，相当于体重（BW）的68.2%。4只双标记动物的FMR为14.05兆焦/天。计算了新的异速生长方程，分别描述了WIR或FMR与BW之间的关系，包括已发表的反刍动物数据和当前羊驼的研究结果。回归方程表明，羊驼的每日WIR与来自干旱和半干旱栖息地的野生或家养反刍动物及骆驼科动物的代谢大小（BW(0.94)千克）相似。由此得出的FMR回归方程解释了超过99%的变异，对应函数为FMR（千焦/天）=1079（BW0.668千克）（n = 5，r2 = 0.995，P < 0.001）。本研究中测量的FMR是首次报道的南美骆驼科物种的数据，表明自由放养的羊驼在代谢体重基础上的能量消耗与生活在恶劣气候条件下的其他野生反刍动物相似。
