Effects of Addition Ratio and Ensiling Days on the Silage Quality of Mixed Chaff and Alfalfa
In this study,different proportions of chaff(0、15%、20%、25%、30%)were mixed with alfalfa for silage.The fermentation quality,nutritional quality and aerobic stability of mixed silage were measured at 0,3,5,7,15,and 30 days of ensiling.The results showed as follows:Compared with con-trol group without chaff addition,the contents of lactic acid and acetic acid in all groups with chaff addition were significantly decreased(P<0.05).Additionally,the pH,the content of propionic acid and butyric acid were decreased but the differences were not significant.The ammonia nitrogen/total nitrogen ratio was increased but the differences was not significant.The addition of chaff indirectly promoted the fermen-tation of isotype lactic acid bacteria and improved the fermentation quality of silage.Except for 30%treat-ment group,the aerobic stability of other chaff treatment group was significantly increased(P<0.05).In all treatment groups,the contents of crude protein and water soluble carbohydrate were significantly decreased(P<0.05),the content of dry matter,crude ash,neutral detergent fiber,acid detergent fiber,acid detergent lignin,cellulose and hemicellulose and hemicellulose were significantly increased(P<0.05).The nutritional quality of mixed silage decreased.Compared with silage raw materials,the con-tents such as dry matter,pH value,water soluble carbohydrate and hemicellulose were significant decreased after 30 days of ensiling,while the contents of crude protein,crude ash,acid detergent fiber,lac-tic acid,and acetic acid were significantly increased(P<0.05).Butyric acid was detected only after three days of ensiling.Linear regression was used to analyze the relationship between silage days and the proportion of mixed bran addition and each index.The results showed that the fermentation index and nutrient index of mixed silage followed the regression prediction model when the added amount of chaff was in the range of 15%to 30%,and the scientific ratio could be made according to the nutritional requirements of different animals.The findings indicated that the quality of mixed silage was the best when the ratio of chaff to alfalfa was 25∶75.
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