Effects of harvest period and mixed ratio on the characteristic and quality of mixed silage of alfalfa and maize

In order to improve the silage quality and rationally develop and utilize feed resources, the experiment will explore the effects of harvest periods and the ratios on silage characteristics and quality of silage maize (Zea mays L.) and alfalfa (Medicago sativa L.). Results showed that dry matter (DM) content, neutral detergent fiber (NDF), acid detergent fiber (ADF) of whole silage maize increased significantly (P < 0.05), water soluble carbohydrate (WSC) content of in 3/4 milk line stage was significantly lower than that in other harvesting stages (P < 0.05), and the CP content of 1/4 milk line stage and relative feed value (RFV) of late milk stage were the maximum, respectively; With the delay of the mowing period, the content of DM, NDF and ADF in the third crop of alfalfa increased significantly (P < 0.05), while the CP content decreased significantly (P < 0.05), the harvest period with the highest RFV was at the early flowering period. To sum up, silage corn can be harvested at the end of milk maturity to early wax maturity, and the third crop of alfalfa can be harvested at the early flowering stage, so that silage materials with high nutritional value can be obtained. The corn silage harvested in late september the best harvest period was mixed with alfalfa at the ratio of 10:0, 8:2, 6:4, 5:5, 4:6, 2:8, 0:10, and the mixed silage was fermented for 60 days, then proceeded determination of silage quality, and the principal component analysis (PCA) was used to analyze 10 nutritional quality indicators of 7 different mixed ratios. The results showed that compared with alfalfa silage alone, in the mixed silage of alfalfa and corn silage, with the increase of the proportion of corn silage, the fermentation quality of silage was gradually improved. Sensory evaluation scores and RFV values were higher, WSC and lactic acid (LA) contents were significantly increased (P < 0.05), and pH and ammonia nitrogen (AN) content were significantly decreased (P < 0.05). The in vitro gas productions ( IVGP, at 0, 2, 4, 6, 8, 12, 24, 36, 48 and 72 h) were measured, the results showed that IVGP increased with the increase of silage corn mixed ratio. In summary, the effects of the harvest period of silage corn and alfalfa and different mixing ratios of silage on the quality of silage provide a theoretical basis for improving the quality of silage and rationally developing and utilizing feed resources, so as to be better applied to actual production.