Abstract: 【Objective】 The objective of this study were to estimate the discrepancy of forage producing performance and the nutrients digestibility of different maize (Zea mays L.) and alfalfa(Medicago sativa L.) intercropping models, thus to provide a scientific basis for applying the intercropping of maize and alfalfa in practice. 【Method】 Four intercropping treatments, alternating alfalfa and maize rows according to 2﹕2, 3﹕2, 4﹕2, 5﹕2, were designed with three replicates for each. Maize and alfalfa sole crop were the control groups. By determining the forage dry matter and nutrients yields, nutrients digestibility, degradable nutrients yields, and rumen microorganism counts of sheep fed harvested alfalfa-maize mixtures from different intercropping groups, to evaluate the forage production potential and explore the mechanism. 【Result】 The results showed that the yields of dry matter, nutrients and utilizable nutrients of maize and alfalfa intercropping system and alfalfa sole crop were all significantly improved along with the advancing of establishing years (P＜0.05); The yields of dry matter between each treatments had no significant difference (P＞0.05); Compared with the maize sole crop, the intercropping system improved the output and digestibility of crude protein (CP) and the yield of degradable CP, additionally, a linearly response was observed with increasing proportion of alfalfa in intercropping; Compared with the alfalfa sole crop, the intercropping system enhanced the yields and digestibility of ether extract (EE), carbohydrate and gross energy, as well as the yields of corresponding utilizable nutrients; The increase of rumen microorganism counts contributed to the enhanced nutrients digestibility and rendered much more straws tissue cells to be digested in rumen, when the harvested mixtures from intercropping were used as ruminant diets. 【Conclusion】 The alfalfa and maize intercropping system have greater forage nutrients yields than alfalfa or corn monoculture, and improve the digestibility of nutrient and the output of utilizable nutrients, thus it is a viable culturing mode for higher forage production, therefore the result can provide a scientific reference for structuring the optimal ruminant forage producing system in the future.

Key words: alfalfa, maize, intercropping, forage potential, mechanism