Approaches To The Diet Selection Behavior Of Grazing Sheep

Animal behavior is one of the activity field in the research of grazing ecology, in which the diet selection are important components of animal foraging behavior. The diet selection is influenced by water resource, characteristics of the studied region and soil, and the plant species and the quality of patches, and the characteristics of the animal physiology and the animal communities. Simultaneity, the spatio-temporal change of the plant communities is an important factor. We studied the animal behavior with sheep happened in the natural grasslands by a controlling experiment in the year 2002 mainly including the selection of plant species, height and density.There are five plant species in the experimental paddock including Leymus chinensis, Phragmites communis, Puccinellia tenuiflora, Aposynum lancifolium and Kalimeris integrifolia. The whole paddock was divided into four hundred small patches. The whole paddock was characterized by the biggest heterogeneity in density, and then the biomass, the height was the last one. The average intake mass in given time and the total intake mass varied with the change of the growth season. The average intake mass peaked the value in the July with 0.329 g/m2*s, then with 0.149 g/m2*s in the September, the lowest in the May. The intake mass correspond to the intake mass within a given time. The biggest value appeared in the July with 1827.104 g/m2. The animal behavior was also impacted by the species in the patches. Sheep favored the patches of P. communis and L. chinensis, then the plants in the patches named with P. tenuiflora or A. lancifolium.The diet selection of sheep happened at patch level was influenced by the change of the season and the plant species. The index in the height selection showed that the index was biggest in the patches of L. chinensis and Kalimeris integrifolia in May, and patches of P. tenuiflora and A. lancifolium in July, and the patches of L. chinensis and A. lancifolium in September. The components of patches was also a key factor in the selection happened at patch level. Generally, the hierarchy for the whole patch was A. lancifolium > Kalimeris integrifolia, P. communis > P. tenuiflora and L. chinensis。The bite depth in the patch of L. chiensis was 3.0 cm in May and 2.2 in July. Because there was few plant available to the animal in September, the utilization in the patch of L. chnensis increased and could reached 7.1 cm. The mean bite depth in the five patch species was 4.1 cm. The grazing behavior was affected by the plant phenology of the plant species, the component in one patch according to the diet depth of sheep.In a word, there was selection behavior happened at patch level. And the selection was impacted by the plant species, the phenology, height and density of the patches. So further research conducted at patch level was need for the study of animal behavior.