Comparative Study On The Effects Of Alfalfa Silage And Alfalfa Hay On Rumen Bacteria And Milk Production Performance Of Dairy Cows

With the continuous expansion of dairy cow farming in china,the self-sufficiency rate of high-quality alfalfa is far from meeting the needs of the development.Therefore,developing high quality alfalfa industry is essential for the dairy industry.How to make efficient use of alfalfa has become the crucial technical difficulties in the process of dairy farming.Whereas,the storage form of alfalfa for the aim to achieve the best production performance is unclear.The main form to storage the alfalfa are alfalfa hay and alfalfa silage.Due to the difference of the production process,there are certain differences in nutritional value and feeding effection for dairy cows.The purpose of this study was to compare the differences in feeding effection,rumen fermentation,bacterial attachment,production performance,composition of raw milk lipid and fat acid of dairy cow fed these two forms.1.The purpose of this experiment is to compare the dynamic degradation of alfalfa hay and alfalfa silage in rumen by nylon bag method,and the variation of attached bacteria during the degradation process.The results showed that the effective degradation rate of neutral detergent fiber of alfalfa hay was significantly higher than that in alfalfa silage,while the slow degradation rate of neutral detergent fiber was significantly lower than that of alfalfa silage（P<0.05）.And,most of bacteria reach the highest level in 24 h during the degradation of feed in rumen,such as Fibrobacteres,Anaeroplasma Abactoclasticum,Fibrobacter succinogenes.2.The second experiment is aim to compare the effection of alfalfa silage and alfalfa hay on milk production performance of dairy cows.42 healthy mid-lactation Holstein cows were selected and randomly divided into three groups with 14 cows in each group.The three group are fed a total mixed ration formulated by alfalfa hay,50%alfalfa hay and 50%alfalfa silage,alfalfa silage for a 3-week pre-feeding and 6-week trial period.The results showed that the pe NDF content of TMR is significantly higher with the addition of alfalfa silage in TMR（P<0.05）.Feeding alfalfa silage and alfalfa hay had a significant variation on milk yield and milk composition of dairy cows.With the increase of alfalfa silage content in diet,the milk production was decreased significantly,while the milk fat,milk fat yield and total solid content increased significantly（P<0.05）,and the total solid yield also tented to increased.The nutrient intake and apparent digestibility of cows fed alfalfa silage were significantly higher than those cows fed alfalfa hay（P<0.05）.3.The purpose of this experiment was to compare the variation of lipid and fatty acid composition in raw milk induced by alfalfa silage and alfalfa hay.The results showed that the major phospholipids such as PC,PE,PS and SM in alfalfa silage group tend to higher than those in alfalfa hay group,in which PC is significantly higher in alfalfa silage than that in alfalfa hay group（P<0.05）,while DAG and Cer were lower than those in alfalfa hay group（P<0.05）.Compared with the alfalfa hay group,the content ofω-6 PUFA in alfalfa silage group was significantly decreased,the content ofω-3 PUFA was significantly increased,and the ratio ofω-6/ω-3 was extremely decreased,the content of functional fatty acids,such as ALA and DPA was significantly increased（P<0.05）.4.The purpose of this experiment was to compare the variation of rumen fermentation parameters and rumen bacterial composition induced by alfalfa silage and alfalfa hay.Results showed that feeding alfalfa silage and alfalfa hay led to the variation of rumen internal environment in dairy cows.The rumen p H and NH₃-N concentration（P<0.05）in alfalfa silage group were significantly lower than those in alfalfa hay group.Feeding alfalfa silage decreased the relative abundance of dominant phyla Firmicutes,and increased the relative abundance of Succiniclasticum ruminis,Selenomonas＿ruminantium,Prevotella＿sp＿＿CA17,Succinimonas＿amylolytica,Succinivibrio＿dextrinosolvens,Methanobrevibacter＿sp＿＿YE315atspecieslevel.Methanobrevibacter＿sp＿＿YE315,Neisseria＿sp＿,Selenomonas＿ruminantium,Succiniclasticum ruminis（P<0.05）in rumen have significant positive correlated with milk fat and milk fat yield.Neisseria＿sp＿and Selenomonas ruminantium also had a significant positive correlation with total milk solids content,while Aerococcus＿urinaeequi had a significant negative correlation with milk fat,milk fat yield and total milk solids content.In conclusion,feeding alfalfa silage and alfalfa hay lead to the variation of the rumen internal environment,resulting in the significant difference in the composition of dominant bacteria in rumen.Feeding alfalfa silage could improve the milk fat,milk fat yield of dairy cows,theω-3 PUFA and the major phospholipids content.Thus,feeding alfalfa silage made the milk lipid composition beneficial for human health.