Where do deer get their sodium from?

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K21338
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 40:Forestry and forest products science, applied aquatic science, and related fields
• Research Institution: Kyushu University
• Principal Investigator: Chiwa Masaaki 九州大学, 農学研究院, 准教授 (30380554)
• Co-Investigator(Kenkyū-buntansha): 内海 泰弘 九州大学, 農学研究院, 准教授 (50346839)
• Project Period (FY): 2020-07-30 – 2024-03-31
• Keywords: シカ / ナトリウム / 草食動物

Outline of Final Research Achievements

In recent years, the population of Japanese sika deer (Cervus nippon) has been increasing rapidly. This study focused on the fact that herbivore, including deer, are prone to sodium deficiency, and hypothesized that water in livestock manure (hereafter referred to as "manure water") and snow on roads sprayed with road salt (hereafter referred to as "road water") may contain high concentrations of sodium and serve as a source of sodium for deer. The sodium concentration in the manure water was 5 mM, about 100 times higher than that in nearby forest soil water. In addition, the sodium concentration in the road water was about 100 mM, which is on the same order of magnitude as the reported sodium concentrations in the water at natural mineral-licks. These results indicate that manure water and road water have high enough concentrations to be a source of sodium for deer.

Free Research Field

生物地球化学

Academic Significance and Societal Importance of the Research Achievements

シカ個体数の管理は農林業被害対策として緊急の課題である．本研究は，これまでシカ増加の原因としてほとんど研究されてこなかったナトリウムに着目した．その理由は，シカを含む植食動物はナトリウム不足になりやすいためである．通常，植物にとってナトリウムは必須元素ではなく，植物中のナトリウム含有量は少ない．本研究では，家畜ふん堆肥中の水や凍結防止剤が散布されている道路上の雪（以下，道路水）中のナトリウム濃度を計測し，シカにとってナトリウム源となりうるほど高濃度であることを明らかにした．