The Effects Of Functional Plants On Foraging Behavior Of Sheep

Taking sheep as research object, we studied intake mass, diet selection and foraging behavior strategies by supplement of different functional plants and improvement of functional group diversity in indoor controlled experiment. This research attempted to examine role of different functional plants and functional group diversity in sheep foraging from the perspective of potential positive effect of plant secondary metabolites (PSM) on herbivores, and preliminarily explore utilization mechanism of herbivore for PSM, which is significant for developing herbivore-plant co-evolution theory.The results of experiment showed as follows:(1) Functional plants can improve intake mass of sheep significantly (P<0.01). In addition, different functional plants had different effects on intake mass of sheep. The average daily intake of sheep on treatments of CK, Apocynum venetum, Kochia sieversiana and Artemisia scoparia was 812.7, 888.1, 955.5, and 805.9g respectively. A. venetum and K. sieversiana can increase intake mass of sheep significantly, whereas A. scoparia did not affect intake mass of sheep. When the number of the Plant Functional Group (PFG) changing, intake mass of sheep showed regularity accordingly. When the number of FG was 1, 2, 3 and 4, intake mass of sheep is 807.3, 930.3, 1017.1, 977.4g, respectively. With the increase of PFG diversity, daily intake of sheep showed improvement significantly.(2) Intake mass of sheep in the afternoon was larger than that in the morning, which wasn't affected by functional plants and the number of PFG. Intake mass of sheep decrease gradually with foraging proceeding. Effects of regulation of A. venetum on intake mass of sheep reduce with lengthening of forging time. However, the effect of regulation of K. sieversiana wasn't affected by forging time of sheep.(3) Different functional plants and the increase of PFG diversity had no significant effects on foraging time of sheep, because sheep almost didn't need to spend time on traveling in the door. Intake rate of sheep showed the consistent regularity with intake mass.(4) Diet selection of sheep was different when different functional plant was supplied. A. venetum and A. scoparia can improve consumption of sheep on leguminous plants with high quality and reduce intake mass and foraging frequency on low-quality gramineous plants, whereas supplement of K. sieversiana can enhance intake mass of sheep on leguminous and gramineous plants.(5) Intake mass and diet switching frequency of sheep increased and selectivity strengthened with the number of PFG increase. Furthermore, function group diversity can relieve negative effects induced by foraging leguminous plants. The content of Na+ in K. sieversiana reaches 0.463%, the content of Na+ in saliva of sheep was enhanced from 0.195% to 0.302% and Na+/K+ rate increases from 2.655 to 6.210 after sheep foraging K. sieversiana. Accordingly, K. sieversiana can be used as supplementary plant of Na+ and play an assistant nutrition role.In summary, some plants which contain PSM can improve and regulate sheep consumption. Conversely, some plants containing plenty of PSM have no significant effects and even show negative effects. The acting mechanism needs to be further studied in the future. Sheep preferred plants with high crude proteins (CP). In addition, PSM can improve utilization ratio of CP and reduce negative effects caused by foraging proteins. Therefore, CP is key factor affecting foraging behavior of sheep. Both PSM and mineral have regulative effects. According to our results, we suggest that improving species richness of plants, especially species richness of different functional plants can contribute to improve nutrient balance and intake mass of sheep, and that proper addition of functional plants is of importance to regulate taste of sheep in livestock husbandry.