Ecological Research (2003) 18, 65–72 Blackwell Science, LtdOxford, UK ERE Ecological Research 0912-38142003 Ecological Society of Japan 181January 2003 533 Parotid and rumen papillae in gazelle Z. Jiang et al. 10.1046/j.0912-3814.2002.00533.x Original Article6572BEES SGML *Author to whom correspondence should be addressed. Present address: Japan Science and Tech- nology Corporation, Laboratory of Animal Ecology, Yamanashi Institute of Environmental Sciences, 5597- 1, Kenmarubi, Kamiyoshida, Fujiyoshida, Yamanashi 403-0005, Japan. Email: jiang@yies.pref.yamanashi.jp Received 22 April 2002. Accepted 19 July 2002. Seasonal changes in parotid and rumen papillary development in Mongolian gazelle (Procapra gutturosa Pallas) ZHAOWEN JIANG, 1 * SEIKI TAKATSUKI, 2 WEN WANG, 3 JUNSHENG LI, 3 KUN JIN 3 AND ZHONGXIN GAO 3 1 Laboratory of Wildlife Biology, School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan, 2 The University Museum, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8654, Japan and 3 College of Wildlife Resources, North-east Forestry University, Hexing Road 26, Harbin 150040, China The Mongolian gazelle (Procapra gutturosa Pallas) lives in the Mongolian Plateau, where conditions are dry and cold from late autumn to early spring. The climate results in apparent seasonal changes in the nutrition of forage plants on the plateau. The morphology of the gazelle’s rumen papillae and the weight of their salivary glands also reflect these changes. The relative weight of the parotids to body mass (0.8–1.3 g kg -1 and 1.8–2.7 g kg -0.75 ) and the surface enlargement factor (SEF) of the internal rumen wall (8.5–12.0) fell within the range of mixed (intermediate) feeders. Although previous studies in a great number of ruminants have shown that parotid mass and SEF are positively related to feed quality, we found that relative parotid mass to body mass increased in winter, the dry and cold season, during the poorest dietary conditions. The surface enlargement factor increased from autumn to winter and spring, during the poorest and best seasons in feed quality, respectively. It is possible that an increase in parotid mass is related to water shortage from both feed and habitat in winter. An increase in parotid mass, suggesting an increase in saliva production, could meet the liquid needs of the gazelles during feeding and rumination in poor and dry forage seasons. The development of rumen papilla and the consequent increase in SEF in poor food seasons should result in the effective absorption of nutrients by Mongolian gazelles. Key words: Mongolian gazelle; parotid; Procapra gutturosa; rumen papillae; seasonal changes. INTRODUCTION The morphophysiological adaptations of the diges- tive organs of ruminants are the result of their coevolution with specifically selected forage plants. This coevolution has genetically influenced the structure and function of the digestive system towards a species-specific optimum, with a wider or narrower range of tolerance revealing an adap- tive ability in acute situations involving food qual- ity and availability, feeding and digestion (Hofmann 1985). The structure and function of the ruminant digestive system are closely related to the forage selected, and rumen papillae and salivary glands are well known indicators of this relationship (Hofmann 1973, 1989; Kay 1987). The relative weight of salivary gland tissue to body mass and the development of rumen papillae are positively related to forage or feed quality (Hofmann 1973, 1985, 1989; Hofmann et al. 1988a,b). Salivary glands secrete saliva at a rate related to food intake and rumination and provide water and alkaline salts (Kay 1987). Two important functions of the parotids are: (i) buffering the excessive acidity of the fermentation products in the rumen; and (ii) carrying or flushing soluble cell contents and