This study was conducted to evaluate the effects of intercropping hairy vetch (HV) with Italian ryegrass (IRG), oat, and rye on forage productivity and nutritive value under a rice-forage double-cropping system. A field experiment was carried out in a paddy field using six treatments (IRG, IRG+HV, oat, oat+HV, rye, and rye+HV) arranged in a randomized complete block design with three biological replications. The results showed that dry matter (DM) yield and total digestible nutrients (TDN) yield were significantly higher in rye monoculture than in the rye+HV mixture, whereas no significant differences were observed between monoculture and intercropping in IRG or oat. In contrast, crude protein (CP) yield increased significantly under intercropping in IRG and oat, confirming the nitrogen contribution and protein-enhancing effects of the legume component. For forage quality, intercropping consistently reduced neutral detergent fiber (NDF) and acid detergent fiber (ADF) concentrations and improved DM intake (DMI), digestible DM (DDM), TDN, and relative feed value (RFV) in all three species. These findings indicate that the productivity-enhancing effect of intercropping is limited under paddy field conditions, while the improvement of forage quality is substantial and consistent. Therefore, intercropping with hairy vetch can serve as an effective strategy in systems where the primary objective is to enhance CP content and overall forage quality.

ABSTRACT
Ⅰ. INTRODUCTION
Ⅱ. MATERIALS AND METHODS
    1. Experimental design
    2. Plant growth and harvest
    3. Chemical analysis
    4. Statistical analysis
Ⅲ. RESULTS AND DISCUSSION
Ⅳ. CONCLUSIONS
Ⅴ. ACKNOWLEDGEMENTS
Ⅵ. REFERENCES

• Sang-Hyun Park(Department of Animal Science, College of Agriculture & Life Sciences, Chonnam National University, Gwangju 61186, Republic of Korea)
• Tae-Hwan Kim(Department of Animal Science, College of Agriculture & Life Sciences, Chonnam National University, Gwangju 61186, Republic of Korea, Institute of Environmentally-friendly Agriculture, Chonnam National University, Gwangju 61186, Republic of Korea)
• Bok-Rye Lee(Institute of Environmentally-friendly Agriculture, Chonnam National University, Gwangju 61186, Republic of Korea) Corresponding author