Comparison Of Nutritional Strategies Of Tibetan Red Deer During Withered Grass Period And Green Grass Period

Plants grow abundantly in the Shannan region of the Tibetan Plateau during green grass period,but wither for up to 8 months during withered grass period.Tibetan red deer(Cervus elaphus wallichii)population distributes in this region coexist with livestock and faces potential competition during green grass period.Meanwhile,Tibetan red deer has to face the harsh environment during withered grass period.I selected typical time of withered grass period and green grass period on the Tibetan Plateau in 2021 and 2022,respectively,to study the food composition and nutritional strategy of Tibetan red deer population in Sangri Tibetan Red Deer Nature Reserve,Shannan,Tibet.Original data on feeding and food composition of Tibetan red deer were obtained by gnawing survey method with direct observation and noninvasive fecal microscopic analysis.By integrating field browsing data with altitude,the fecal microscopic analysis data with plant nutrient measurements,we compared nutritional strategies of Tibetan red deer during withered grass period and green grass period.Data mining was performed in two-dimensional Euclidean space to study the nutrition strategies of Tibetan red deer population at different time inceptions under the time scale,that can be matched with sample collection methods.Research would fill the gaps in the nutritional ecology of Tibetan red deer during withered grass period and provide foundation for the comprehensive revealing of the nutrient ecological process of Tibetan red deer acclimating to plateau ecosystem.The main results are as follows:(1)The results of direct observation in the field showed that Tibetan red deer mainly fed on Salix daltoniana,Dasiphora parvifolia and Rosa macrophylla var.glandulifera during withered grass period.They fed on R.macrophylla,Berberis temolaica and Artemisia wellbyi in low elevation area of the reserve,and fed on Poa annua,Anemone rivularis,Sibiraea angustata and Carex littledalei in the higher elevation area.The Tibetan red deer mainly fed on S.daltoniana,P.annua and C.littledalei during green grass period.They fed on P.annua in low elevation area,and chose to feed on S.daltoniana and C.littledalei in high elevation area.(2)The results of fecal micro-histological analysis showed that Tibetan red deer fed on 20 species of plants from 13 families during withered grass period,with S.daltoniana,Rhododendron fragariiflorum and Juniperus pingii var.Wilsonii as staple food,46 species of plants from 17 families during green grass period,with S.daltoniana,P.annua and C.littledalei as staple food.There was no significant difference in the proportion of Tibetan red deer eating Salicaceae during withered grass period and during green grass period,but the proportion of the red deer eating Rosaceae,Ericaceae and Cupressaceae was significantly higher than that in the green grass period.Proportion of Fabaceae,Asteraceae and Poaceae was significantly lower than that of green grass period.Proportions of arbors and shrubs were significantly higher than that in the green grass period and proportion of feeding on forbs and graminoids was significantly lower than that in the green grass period.Compared with green grass period,food composition pattern in the withered grass period showed a higher proportion of Hippophae tibetana,Ceratostigma ulicinum and B.temolaica.Some individuals of Tibetan red deer had food composition pattern dominant by R.macrophylla during withered grass period.Most Tibetan red deer had a food composition pattern mainly composed of P.annua and C.littledalei during green grass period,while a few Tibetan red deer individuals had a food composition pattern mainly composed of R.fragariiflorum and J.pingii.Contents of crude protein,ash and non-structural carbohydrate in grazing plants of Tibetan red deer during withered grass period were lower than those during green grass period,while the contents of neutral detergent fiber,acid detergent fiber,acid detergent lignin and carbohydrate were higher than those during green grass period.Contents of crude protein and acid detergent lignin were higher in arbors and shrubs.Contents of neutral detergent fiber,acid detergent fiber and carbohydrate in graminoids were the highest,while non-structural carbohydrate contents were the lowest.(3)Concentrations of crude protein,ash and non-structural carbohydrate of Tibetan red deer during withered grass period were significantly decreased compared with those during green grass period,but concentrations of crude fat,neutral detergent fiber,acid detergent fiber and carbohydrate were significantly increased.Results of RMT showed that the relative contribution rate of crude protein and crude fat during withered grass period was close to 1:1.8,and relative contribution rate of crude protein and crude fat during green grass period was close to 1:0.9.Relative contribution rate of carbohydrate remained stable,ranging from 76.95% to85.82%.Relative contribution rate of non-fiber energy-supplying nutrients in the green grass period was higher than that in the withered grass period,but relative contribution rate of nonfiber energy-supplying nutrients and non-nutrient components during withered grass period and during green grass period was close to 3:1.