Inhibition effects of volatile organic compounds from Artemisia frigida Willd. on the pasture grass intake by lambs

- A. frigida released lots of VOCs, and terpenoids were the abundant compounds.
- A. frigida shoots reduced grass intake for the intense odor.
- Inhibition of food intake by 3 terpenoids showed terpenoids playing a major role.
- The protection of VOCs promoted A. frigida to become the dominating species.
- The intense odor from A. frigida may influence the livestock production.

Plants release a wide spectrum of volatile organic compounds (VOCs) which can defense against herbivores. In previous studies, we found that VOCs from Artemisia frigida Willd. had strong allelopathic effects on local plants, which facilitated A. frigida dominance in heavily grazed and degraded grasslands. However, it is unknown whether these VOCs from A. frigida can affect the ingesting behavior of sheep. In this study, we analyzed the composition of VOCs from A. frigida grown in heavily grazed and degraded grasslands. The food intake, feeding time and feeding rate were determined after the lambs were supplied with local pasture grasses mixed with A. frigida shoots or sprayed with 1,8-cineole, β-pinene and α-terpineol, respectively. Terpenoids, which were the abundant compounds among A. frigida VOCs, mainly included 1,8-cineole, β-pinene, α-terpineol, m-cymene, camphor, ρ-menth-1-en-4-ol and β-terpineol. When local pasture grasses were mixed with A. frigida shoots, the food intake by lambs, according feeding time and feeding rate were inhibited markedly, with the inhibitory effect of 51.8%, 20.0% and 39.8%, respectively, in the treatment with 30% A. frigida. The inhibitory effects were also found in the treatments with 1,8-cineole, β-pinene and α-terpineol, in which 1,8-cineole had the strongest effects on the ingestion. These results showed that the VOCs (mainly terpenoids) can protect A. frigida from intake by sheep, which might also promote the plant to become the dominant species in heavily grazed and degraded grasslands. We suspected that the intense odor of terpenoids from A. frigida might influence pasture grass intake by sheep and even livestock production.