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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2008-1544v1 87/7/2355    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Wang, H. Articles by Guo, X. PubMed PubMed Citation Articles by Wang, H. Articles by Guo, X.

A comparative study on urinary purine derivative excretion of yak (Bos grunniens), cattle (Bos taurus), and crossbred (Bos taurus x Bos grunniens) in the Qinghai-Tibetan plateau, China¹

H. Wang^*,, R. Long^*,,2, W. Zhou, X. Li, J. Zhou and X. Guo^*

^* International Centre for Tibetan Plateau Ecosystem Management, Lanzhou University, Lanzhou 730020, China; and Tibetan Rangeland and Yak Research Institute, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China; and Gansu Entry-Exit Inspection and Quarantine Bureau, Lanzhou 730020, China

² Corresponding author: Longrj{at}lzu.edu.cn

Two experiments were conducted to determine the urinary purine derivative (PD) excretion rates and to analyze potential variations in PD excretions between yak, Tibetan indigenous cattle, and their crossbreds under similar ecological environment, and to develop prediction equations based on PD excretion for estimating rumen microbial protein supply. Three Tibetan castrated male yaks, and similar numbers of indigenous cattle and their crossbreds, were used in a fasting trial followed by a feeding trial, using three 3 x 3 Latin squares (1 for each breedtype), to 4measure responses of PD excretion to different feeding levels. The results showed that i) daily endogenous PD excretion for yak, indigenous cattle, and their crossbreds was 134, 163, and 138 µmol/kg of BW^0.75 (P = 0.38), respectively; and ii) crossbreds have greater PD excretion rate per unit digestible OM intake than indigenous cattle (P = 0.03). However, there were no significant differences between yaks and the crossbreds (P = 0.24) or between yaks and the indigenous cattle (P = 0.25). The proportion of allantoin to total PD in urine ranged from 0.83 to 0.88, with the crossbreds having greater values compared with the 2 parents (P = 0.03). Daily glomerular filtration rate, calculated using endogenous creatinine as an internal marker, for the above animals was 3.85, 4.23, and 3.61 L/kg of BW^0.75, respectively, in fasting trial (P = 0.59). The alpine animals may develop special regulating mechanisms in the kidney in terms of glomerular filtration rate and PD excretion, which would help the animals in adapting to the harsh environment of the Qinghai-Tibetan plateau.

Key Words: allantoin • cattle • creatinine • glomerular filtration rate • Qinghai-Tibetan plateau • yak