Effects Of Dietary Copper And Molybdenum Levels On Blood Biochemical Indexes、Digestion Metabolism And Rumen Microorganisms Of Sunit Sheep

Based on the investigation of lamb death in the northern desert steppe of Inner Mongolia in recent years,the effects of different supplemental levels of copper(Cu)and molybdenum(Mo)on blood biochemical indexes,digestion and metabolism and rumen microflora of Sunit ewes were studied,aiming to solve the practical problem of high incidence of secondary copper deficiency in desert steppe during production.Twelve healthy Sunit ewe with the same age and similar body weight(43±2.3 kg)were randomly divided into 3 groups with 4 sheep per group.The experiment was divided into 3 phases(14 days per phase,7 days per prefeeding period and 7 days per trial period),with a total of 42 d.Capsules with different Cu and Mo contents were added to each group after morning feeding.The level of Mo in the first phase was 1 mg/kg(low molybdenum group),the level of Mo in the second phase was 4 mg/kg(medium molybdenum group),and the level of Mo in the third phase was 6 mg/kg(high molybdenum group).The supplemental levels of Cu in diets were 5 mg/kg(low copper group),10 mg/kg(medium copper group)and 15 mg/kg(high copper group),respectively.Blood samples from jugular vein were collected at each stage to determine the activity of blood copper,serum Ceruloplasmin(Cp)and plasma Superoxide dismutase(SOD).Rumen fluid was collected at each stage to determine the rumen microflora.In the third phase of the experiment,combined with the actual production,the effects of different Cu supplemental levels on the digestion and metabolism of the body were studied under the high Mo level of the diet,and the digestion and metabolism experiment was carried out by the total fecal collection method.The results showed as follows:(1)different Cu levels in the diet had significant effects on blood copper content after 2 h of capsule feeding(P<0.05),and different Mo levels in the diet had significant effects on blood copper content after 8 h of capsule feeding(P<0.01).Under the same Cu level,blood copper content was significantly decreased with the increase of dietary Mo level(P<0.05);Under medium and high Mo diet conditions,all three Cu levels will lead to blood copper deficiency over time.Different supplemental levels of Mo had a significant effect on Cp activity(P<0.05),while different supplemental levels of Cu and their interaction had no significant difference on Cp activity(P>0.05).Under the same Cu level,Cp activity decreased significantly with the increase of Mo level in the diet(P<0.05).Different levels of Mo in the diet had significant differences on SOD activity(P<0.01),but different levels of Cu in the diet and their interaction had no significant differences on SOD activity(P>0.05),indicating that SOD activity was sensitive to the changes of Mo in the diet.Under the same Cu level,SOD activity decreased significantly with the increase of Mo supplemental level(P<0.05).(2)Under the same Cu level,the richness and diversity of rumen microflora decreased with the increase of Mo supplemental level in diet;At the same Mo level,the richness and diversity of rumen microbial flora increased with the increase of Cu supplemental level in the diet,and the appropriate Cu and Mo supplemental levels could keep the internal environment of rumen microbial stable.Firmicutes,Bacteroidetes and Actinobacteria are the dominant bacteria with different added amounts of Cu and Mo,and their dominant position does not change with the change of added amounts of Cu and Mo.After capsule feeding for 2 h,the effect of Mo level in the diet on the relative abundance of Actinobacteria,Bacteroidetes,Proteobacteria and Spirochaetes was significant(P<0.05).The effect of Cu level in the diet on the relative abundance of Firmicutes,Actinobacteria,Bacteroidetes,Proteobacteria and Spirochaetes was significant(P<0.05).After capsule feeding for 8h,the effect of Mo level in the diet on the relative abundance of Firmicutes,Actinobacteria and Spirochaetes was significant(P<0.05).Under the same Cu level,with the increase of Mo level in the diet,the relative abundance of Firmicutes and Bacteroidetes was significantly decreased(P<0.05),while the relative abundance of Actinobacteria was significantly increased(P<0.05).Under the same Mo level,with the increase of Cu supplemental level,Bacteroidetes and Bacteroidetes in the diet could increase the relative abundance of Actinobacteria.The relative abundance of Firmicutes showed an increasing trend(P<0.05).At the genus level,Ruminococcus＿2 is the dominant genus.When 15mg/kg Cu is added at high Mo level,Ruminococcus＿2 is higher,and the overall relative abundance of Bifidobacterium is significantly higher than that at low Mo level.At low Cu and high Cu levels,Olsenella was significantly increased with the increase of Mo supplemental level(P<0.05).Adding appropriate Cu and Mo can improve the immune ability and fiber degradation of animal body.(3)Under the condition of high Mo,the digestibility of crude protein,neutral detergent fiber,acid detergent fiber,crude fat and organic matter showed an increasing trend with the increase of Cu supplemental level in the diet.In conclusion,under the condition of high Mo diet,high Cu level can increase the content of copper in blood,SOD activity in plasma and Cp activity in serum.With the increase of Cu level,the bacterial community of fibrinolysis in rumen increases.High Cu level can improve the nutrient digestibility of Sunit sheep by improving the degree of nutrient metabolism in the body.