These experiments were to investigate the variations of rye on forage quality, productivity and β-carotene concentration affected by maturity in Pyeongchang region. Limited information are available about how forage quality and β-carotene content are affected by various factors. Samples were collected from rye harvested every 5 days, from April 25 to May 31 (April 25, April 30, May 4, May 9, May 15, May 21, May 25 and May 31). Dry matter (DM) content, plant height, DM yield and total digestible nutrient (TDN) yield increased continuously with the progressed maturity. However, crude protein (CP) content, in vitro dry matter digestibility (IVDMD) and relative feed value (RFV) decreased markedly with the delay of harvesting, while TDN content decreased from April 25 till May 15, then followed by a stable fluctuation. Conversely, acid detergent fiber (ADF) and neutral detergent fiber (NDF) value increased and then fluctuated slightly after blooming stage. For quality of plant parts, stem contained the lowest CP content and RFV value, and the highest ADF and NDF contents compared with other parts, while the grain showed the higher CP, IVDMD, RFV and lower fiber contents than others. With the plant matured, leaf proportion decreased while stem and grain proportion increased, and feed value of all the three parts decreased till blooming stage and followed by a stable phase. β-carotene concentration showed its highest on jointing stage, and then fell down sharply on the sequential stages. In conclusion, harvest around May 15 (blooming) is proper for forage rye if directly consumed by livestock as green chop in Pyeongchang under the consideration of both nutritive yield and forage quality.

ABSTRACT
Ⅰ. INTRODUCTION
Ⅱ. MATERIALS AND METHODS
    1. General information
    2. Preparation of rye
    3. Chemical analysis of rye
    4. Statistical analysis
Ⅲ. RESULTS AND DISCUSSIONS
    1. Effect of harvest dates on agronomic characteristicsand yield composition
    2. Effect of harvest dates on forage quality of rye
    3. Effect of harvest dates on β-carotene content
    4. Effect of harvest dates on leaf-stem-grain ratio
    5. Effect of plant parts and harvest dates on feed valueof forage rye
Ⅳ. CONCLUSION
Ⅴ. ACKNOWLEDGEMENT
Ⅵ. REFERENCES

• Guo Qiang Zhao(Graduate School of International Agricultural Technology, SNU)
• Sheng Nan Wei(Graduate School of International Agricultural Technology, SNU)
• Yan Fen Li(Graduate School of International Agricultural Technology, SNU)
• Eun Chan Jeong(Graduate School of International Agricultural Technology, SNU)
• Hak Jin Kim(Research Institute of Eco-friendly Livestock Science, GBST, SNU)
• Jong Geun Kim(Graduate School of International Agricultural Technology, SNU/Research Institute of Eco-friendly Livestock Science, GBST, SNU) Corresponding author