The objective ot this study was to determine the most proper harvesting stage for sainfoin harvested at five different maturities (budding, 25% blooming. 50% blooming, 100% blooming and seedling) using in vivo and in vitro digestibility. Dry matter (DM), organic matter (OM), neutral detergant fiber (NDF), acid detergant fiber (ADF) and acid de-tergant lignin (ADL) contents of sainfoin increased, but crude protein (CP) and ash contents decreased due to increased maturity (P<0.05) DM, OM, CP, NDF, ADF and ADL concentrates were 11,65%, 17.39%, 23,49%. 28.96% and 30.59%; 90 75%, 92 19%, 93.13%, 94.04% and 93.76%; 21.62%, 16 06%, 12.35%, 12.31% and 11.60%; 4012%, 48.38% 52.31%. 52.03% and 55.38%; 29.72%, 37.92%, 41,71%, 40,39% and 44.22%; 6.69%, 7.15%, 8.04%, 9.48% and 9 31% for 1 2 3. 4 and 5th harvesting stages, respectively (P<0.05). DM yield, in vitro OM digestibility (IVOMD), digestible energy (DE), metabolizable energy (ME), net energy for lactation (NEL) levels of sainfoin were 333.5, 629.2. 815.2, 1112.6 and 1020.9 kg/da. 71 15%. 63 94, 62.69%, 56.63% and 58.36%;13 13, 11.80, 11.57, 10.45 and 10.77 MJ/kg DM; 10,76, 9 67, 9 48, 8.57 and 8.83 MJ/kg DM; 6.79, 6.05, 5.93, 5.30 ve 5 48 MJ/kg DM for 1. 2. 3. 4. and 5«ı harvesting stages, respectively (P<0.05). Coefficiencıes ot DM. OM, CP, NDF, ADF digestibilities determined in vivo were 69 95. 68.39%. 62 95%, 61 60% and 58 85%; 71.80%. 69.88%. 64,54%, 62.34% and 5961%: 78.04%, 76.63%, 71.11%. 65.22% and 72 28%; 47.91%, 4111%, 43.46%, 42.38% and 40,18%; 46.78%, 36.28%. 37.18%, 36.92% and 33.84% (or 1. 2. 3 4. and 5m harvesting stages, respectively (P<0.05). DE, ME and NEL levels determined in vivo were 13.25, 12.89, 11.91. 11.50 and 11 00 MJ/kg DM; 10.86, 10.57. 9.76, 9.43 and 9.02 MJ/kg DM; 6,86, 6.66, 6.11, 5 89 and 5 61 MJ/kg DM. Organic matter digestibilities and energy contents of samples were similar wnen in vitro ar>d in vivo techniques were compared except tor organic matter digestibilities at 2 and 4th harvesting stages. Even though IVOMD decreased, in vitro digestible OM yields increased with maturity because of increases in DM yields of sainfoin with maturity The highest in vitro digestible OM yield were observed at 3., 4.. and 5th harvesting stages (50% blooming, 100% bSooming and seedling). Similariy, the highest DE, ME and NEL values were observed at same harvesting stages (P<0.05).