| In recent years,China dairy industry is developing rapidly.To alleviate the dependence on imported feed resources and solve the problem of shortage of domestic high-quality feed resources,it is important to develop unconventional feed resources.Mulberry（Morus alba L）,as an edible medicinal plant,is planted in more than 20provinces in China.Previous studies have shown that mulberry branches and leaves（MBL）could be used as feed resources in the production of sheep and beef cattle.However,Few studies had applied for dairy cows and the effect on rumen environment of dairy cows is still unclear.Therefore,5%and 10%of MBL silage were added to the cow’s dairy diet to ensure that the nitrogen level in each group were equal.Hence,This study aims to determine the effects of MBL silage on the production performance,blood metabolism and rumen environmentof dairy cows,which provided theoretical basis for the application of MBL silage on dairy cow production.1.Effects of MBL silage on lactation performance and blood metabolism in Holstein dairy cowTo explore the effects of MBL silage on lactating performance and blood metabolism of dairy cows.A total of 36 mid-lactating Holstein cows were randomly divided into 3 groups according to parity,lactation days,body weight and milk production,with 12 cows in each group.The control group（C）was fed the pasture TMR diet,the 5%MBL silage group（L）and the 10%MBL silage（H）group were added to 5%and 10%MBL silage to replace silage corn,adjusting the dosage of alfalfa hay and oat grass to make the energy-nitrogen ratio similar in all groups.During the trial period,the MBL were collected for the determination of biologically active ingredients and nutrient content.Feed and milk samples were collected every week for detection of feed intake,milk production and milk composition.Meanwhile,the blood samples were gathered at week 3 and 6 for plasma physiological and biochemical parameters determination.The results showed that the biologically active components of mulberry leavest are mainly palmitic acid（5.42%）,melibiose（3.13%）,choline（1.71%）,4-hydroxycoumarin（1.56%）and vaccenic acid（1.13%）and so on.The replace of MBL silage had no significant effects on the dry matter intake（DMI）and the apparent digestibility of nutrient component in each group.With the replace of MBL silage,milk fat yield,milk fat percentage,lactose yield increased significantly（P<0.05）,and 4%FCR tend to improve（P=0.10）.The 4%FCM,ECM,milk protein yield,milk protein rate,lactose rate,and total solid content in each group had no significant differences,but the effect of MBL silage groups was better than that of C group.In terms of blood metabolism,the replace of MBL silage had no significant effect on blood biochemical metabolism indexes（P>0.05）.The MDA content of group L was significantly lower than that of C group（P=0.04）,the SOD content increased linearly,extremely significantly higher than that of C group（P<0.01）,the Ig A content of H group was significantly higher than that of C group（P=0.02）.These results suggested that MBL silage could improve lactating performance and blood antioxidant capacity of dairy cows.2.Effect of MBL silage on the rumen environment in Holstein dairy cowsTo investigate the effects of MBL silage on rumen environment of dairy cows,rumen fluid was collected in the last week to check rumen fermentation parameters and microbial diversity.The results showed that the replace of MBL silage had no significant effect on the rumen p H,NH3-N,acetic and TVFA content.With the increasing of MBL silage,the concentration of propionic acid was significantly increased（P<0.05）,the rumen ethylene-propylene ratio was reduced（P<0.05）.Moreover,the increasing of MBL silage changed the rumen fermentation mode of dairy cows,which could significantly change the structure of rumen bacterial colony but didn’t significantly change theα-diversity of rumen microorganism.A total of 247genera of microorganisms were detected in 3 groups of samples.the dominant phyla are Bacteroides,Firmicutes,and Proteobacteria at the phylum level.With the increase of MBL silage,the abundance of Bacteroides significantly decreased（P<0.01）,compared to the control group.the abundance of Bacteroides in group L and H were reduced by 20.97%and 28.98%（P<0.01）.The Firmicutes and Proteobacteria abundance increased but not significantly,the abundance of Firmicutes in group L and H increased by 30.88%and 34.95%（P>0.05）,respectively,Proteobacteria abundance in group H was extremely significantly higher than Cgroup（P<0.01）.At the genus level,compared with the control group,the abundance of Prevotella in the L and H groups was reduced by 29.66%and 36.14%,respectively（P<0.05）,Succinivibrionaceae＿UCG-001 in the H group was increased by 68.69%（P>0.05）,Ruminococcaceae＿NK4A214＿group and Succiniclasticum in group L increased by33.15%and 73.62%,respectively（P>0.05）.Linear discriminant analysis with LEf Se software（LDA=2.5）showed that the characteristic microorganisms with significant abundance difference in group H are mainly Firmicutes which were considered as fiber degradation function,including Lachnoclostridium,Coprococcus,Ruminococcus＿gauvreauii＿grou,Lactobacillus and Desulfobacterota（Desulfovibrio）which are positively related to the synthesis of milk fat.Correlation analysis of environmental factors showed that a total of 8 species of bacteria were significantly positively correlated with the concentration of propionic acid,all belonging to Firmicutes,and 4 significantly negatively species which belonging to Bacteroides.It suggestedthat adding MBL silage couldaddthe abundance of Firmicutes that related to fiber degradation,milk fat synthesis and propionic acid production in the rumen,thereby changing the rumen fermentation mode and increasing the milk fat rate of dairy cows.In summary,as feedstock for dairy cows,the MBL silage could regulate rumen fermentation mode and microbial composition,promoting degradation of feed fiber,rumen propionic acid production and milk fat synthesis,increasing milk fat percentage,milk fat yield,lactose yield and blood antioxidant capacity,to improve the lactation performance of dairy cows. |
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