| In order to take full advantage of forage resource in Tibet and improve the nutritional value of the silage,this study choosed crop straw,grasses and legumes as fermented materials and maked mixed silage.The fermentation quality and nutritive value of mixed silage with different proportions were investigated and a suitable proportion of mixture was screened.The purpose is to improve the nutritional value of the silage on the basis of ensure good fermentation quality.There are five experiements in this study.Experiment 1:Effects of different mixed ratio of hullessbarley straw,tall fescue and legumes on fermentation quality and crude protein content.Based on the fresh weight ratio(4:6)of hullessbarley straw and tall fescue,silage was mixed with 0%,10%,20%and 30%of legumes(alfalfa or common vetch).The results show that,when silage was mixed with legumes,the pH value had no significant difference(P>0.05),the fermentation quality improved and the crude protein content increased.As for the alfalfa group and the common vetch group,both of them had no significant difference in the pH value,lactic acid and butyric acid content,however,the AN/TN of common vetch group was lower(P>0.05)or significantly(P<0.05)lower than that of the alfalfa one.Therefore,when silage was mixed with barley straw and tall fescue,common vetch was better than alfalfa.With the increase of the legumes proportion,the pH value had no significant difference(P>0.05),but lactic acid,protein content and AN/TN showed an uptrend.From the perspective of fermentation quality and crude protein content,it is recommended that 28%hullessbarley straw + 42%tall fescue + 30%alfalfa or common vetch is more appropriate.Experiment 2:Effects of different mixed ratio of wheat straw,tall fescue and legumes on fermentation quality and crude protein content.Based on the fresh weight ratio(4:6)of wheat straw and tall fescue,silage was mixed with 0%,10%,20%and 30%of legumes(alfalfa or common vetch).The results show that,when silage was mixed with alfalfa,the pH value and butyric acid had no significant difference(P>0.05),but the lactic acid content,AN/TN and dry matter digestibility rose obviously and the crude protein content increased(P<0.05).When mixed with wheat straw and tall fescue,common vetch was better than alfalfa.With the increase of the alfalfa proportion,the pH value and AN/TN had no significant difference(P>0.05),but the crude protein content increased.From the perspective of fermentation quality and crude protein content,28%wheat straw + 42%tall fescue + 30%alfalfa is more appropriate.In the common vetch group,different mixing ratios had no influence on crude protein content,and the common vetch ratio of 20%had the minimum pH and AN/TN,it is recommended that 32%wheat straw + 48%tall fescue + 20%common vetch is more appropriate.Experiment 3:Effects of different mixed ratio of oat straw,tall fescue and legumes on fermentation quality and crude protein content.Based on the fresh weight ratio(4:6)of oat straw and tall fescue,silage was mixed with 0%,10%,20%and 30%of legumes(alfalfa or common vetch).The results show that,when silage was mixed with alfalfa,the pH value was lowered to 4.2,dry matter and butyric acid content decreased,the lactic acid,crude protein contents and AN/TN increased,but there were no significant difference(P>0.05).When mixed with common vetch,the pH value reached up about 5.0,the buyric acid content and AN/TN were extremely high,which is a typical clostridial fermentation.Comparing the two mixed silage,the alfalfa is better than the common vetch.With the increase of alfalfa proportion,the pH value,AN/TN,lactic acid and butyric acid contents had no significantly different(P>0.05),but the crude protein content increased.From the perspective of fermentation quality and crude protein content,it is suggested that 28%oat straw + 42%tall fescue +30%alfalfa is more appropriate.With the increase of common vetch proportion,the crude protein content increased,however,the pH value and butyric acid levels of 30%common vetch group were significantly(P<0.05)higher than the 20%common vetch group,it is proposed that 32%oat straw + 48%tall fescue + 20%common vetch is more appropriate.Experiment 4:Effects of different mixed ratio of rape straw,tall fescue and legumes on fermentation quality and crude protein content.Based on the fresh weight ratio(4:6)of rape straw and tall fescue,silage was mixed with 0%,10%,20%and 30%of legumes(alfalfa or common vetch).The results show that:when silage was mixed with alfalfa,the pH value and dry matter content were significantly(P<0.05)lowered,the AN/TN and butyric acid content declined,the fermentation quality improved.The crude protein content and acid detergent fiber digestibility significantly(P<0.05)increased.When mixed with common vetch,the pH value was significantly(P<0.05)increased,however,butyric acid were significantly(P<0.05)decreased,although AN/TN rose but still within the standard range,the fermentation quality was also better.With the increase of alfalfa proportion,the pH value had no significant difference(P>0.05),the AN/TN gradually rose,and the 20%alfalfa group had the highest crude protein content and the lowest butyric acid content.With the increase of the common vetch proportion,the pH value was rising,the lactic acid content was decreasing,the AN/-TN was gradually increasing,20%and 30%vetch group had a similar crude protein content.From the perspective of increasing straw utilization and improving the crude protein content,it is suggested that 32%rape straw + 48%tall fescue + 20%alfalfa or common vetch is more appropriate.Experiment 5:Effects of different mixed ratio of maize straw and legumes on fermentation quality and crude protein content.Basing on the fresh weight ratio of 100:0,90:10,80:20 and 70:30,maize straw and legumes(alfalfa or common vetch)was mixed.The results show that,when silage was mixed with legumes,the pH value was still as low as about 4.0 although it was slightly higher,the dry matter,lactic acid and crude protein content increased,the AN/TN lowered,the butyric acid was significantly(P<0.05)reduced.The fermentation quality improved.Both the alfalfa group and common vetch group had good fermentation quality.With the increase of the legumes proportion,the pH value increased slightly and the butyric acid content decreased,the crude protein content increased.From the perspective of improving the crude protein content,it is proposed that 70%maize straw + 30%alfalfa or common vetch is more appropriate. |
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