The Effect of Growth Stage and Cutting on Agronomic Traits, Chemical Composition and Nutritional Value of Sainfoin

In this study, the effect of different growth stages and cuttings on agronomic traits, chemical composition, and nutrient digestibility of sainfoin (Onobrychis viciifolia) in 2003-2004 cropping season was investigated. Chemical composition was measured by standard laboratory method and the nutrient digestibility by using 20 Mehraban male lambs. Agronomic traits and chemical composition data were obtained from a factorial experiment arranged within a completely randomized design. Nutrient digestibility coefficients were determined in a completely randomized design. The growth stages included full budding (I), early flowering (II), and full flowering (III), and the cuttings included first, second, third, and fourth cuttings. The bush height, wet and dry weight of forage, DM%, and NDF% increased with the advancement of plant age, and on the contrary the leaf: stem ratio, CP%, and NFC% decreased. There was significant difference for bush height at three growth stages and for leaf: stem ratio at stage I as compared with other stages (P<0.05). The effect of cutting on agronomic traits was significant, so that bush height increased from second cutting to fourth cutting and leaf: stem ratio decreased. Bush CP and NDF differed significantly between different cuttings and were 21.41% and 37.82% for stage I, 19.47% and 42.20% for stage II, and 18.21% and 48.79% for stage III, respectively (P<0.05). The crude protein of bush at fourth cutting (20.73%) was significantly higher than other cuttings and bush NDF at first cutting (40.68%) was significantly lower than other cuttings (P<0.05). The digestion coefficients of DM, CP, NDF, NFE, OM, CF and TDN decreased significantly with the advancement of growth stage (P<0.05). Results show that sainfoin at early flowering stage and third cutting has more desirable qualitative and quantitative capabilities.