Study On Different Forms Of Selenium And Appropriate Supplemental Levels Of Beef Cattle

This study first adopted an in vitro method.To study the effects of different levels o Na₂SeO₃ and yeast selenium on the rumen fermentation parameters of Jinjiang cattle to select the most appropriate amount of Na₂SeO₃and yeast selenium,Then adopt in vitro and rearing methods,comparing appropriate adding amount of Na₂SeO₃and yeast selenium to jinjiang cattle apparent digestibility of nutrients,blood indexes,rumen fermentation,and the influence of rumen microflora,aimed to provide basis for application of beef cattle production.This experimental study consists of 4 parts,and the design of each part is as follows:Section 1 Effects of Different Additions of Na₂SeO₃on Rumen Fermentation Parameters of Jinjiang Cattle（In vitro Experiment）.Three Jinjiang cattle with the same weight and permanent fistulas were selected,and the liquid was collected from three points in the rumen before morning feeding.Used for in vitro batch culture and fermentation of Na₂SeO₃.A single factor design was used for in vitro fermentation experiment.Six supplemental levels of sodium selenite（Secontent 1%）were set as 0.0 mg/kg,0.1 mg/kg,0.2 mg/kg,0.3 mg/kg,0.4 mg/kg and 0.5 mg/kg,respectively,and each supplemental dose was set as 4 replicates.The results show that:（1）Compared with the control group,the pH of rumen fermentation fluid in experimental groups was significantly decreased（P<0.01）,and the pH of group F was the lowest（2）ADietary supplementation of sodium selenite in groups D and E significantly increased the concentration of MCP in rumen fermentation fluid（P<0.01）;（3）The effect of dietary sodium selenite supplementation on NH3-N was firstly increased and then decreased,and the concentration of NH₃-N in group D was significantly increased（P<0.01）;（4）Rumen substrate IVD_MD in group D was significantly increased（P<0.05）;（5）The effect of sodium selenite on rumen fermentation broth GP was not significant（P>0.05）;（6）Group D significantly increased the concentration of total volatile fatty acids（TVFA）（P<0.01）,and also significantly increased the concentrations of acetic acid,propionic acid,isobutyric acid,valerate and isobutyric acid（P<0.01）.Compared with group A,group D decreased by 0.20%and the difference was significant（P<0.05）,but the increase of butyric acid concentration was not significant（P<0.01）,Compared with group A,the VFA in group D decreased by 0.20%（P<0.05）,while the increase of butyric acid concentration had no significant difference（P>0.05）.When sodium selenite was added at other concentrations,the VFA showed A trend of decreasing at first and then increasing.In conclusion,the optimal dietary Na₂SeO₃supplemental level is 0.3 mg/kg.Section 2 Section 2 The effect of different levels of yeast selenium on rumen indicators（in vitro Fermentation）.Three Jinjiang cattle fitted with permanent fistulas with the same body weight were selected.Rumen fluid was collected by three-point method before morning feeding for batch culture and fermentation of selenium yeast in vitro.Six supplemental levels of yeast selenium（0.1%Secontent）were set as 0.0 mg/kg,0.1 mg/kg,0.2 mg/kg,0.3 mg/kg,0.4mg/kg and 0.5 mg/kg,and each supplemental dose was set as 4 replicates.The results indicate that:（1）Ⅳ,Ⅴgroup compared with pHⅠgroup decreased significantly（P<0.05）;（2）Adding selenium yeast had no significant effect on NH3-N and MCP of rumen fermentation broth compared with the control group（P>0.05）.（3）IVD_MDⅣgroups increased significantly compared withⅠgroup（P<0.05）;（4）Ⅱgroup compared withⅠgroup gas production increased significantly（P<0.05）;（5）Ⅳgroup of rumen fermentation liquor propionic acid,butyric acid,pentanoic acid,isovaleric acid significantly increased compared withⅠgroup（P<0.05）;（6）Ⅴyeast selenium andⅠgroup improved significantly compared with isobutyric acid and total volatile fatty acids（P<0.05）;Ⅳgroup b/c significantly reduced（P<0.05）;The effect of selenium yeast supplementation on acetic acid content of rumen fermentation fluid was not significantly different from that of control group（P>0.05）.Thus it can be seen,The appropriate amount of yeast selenium in the diet is 0.3 mg/kg.Section 3 Comparison of Effects of Appropriate Supplementary Doses of Na₂SeO₃and Effect of Yeast Selenium on Rumen Index of Jinjiang Cattle（in vitro Test）.According to the results of the first and second sections,the purpose is to further study the effects of sodium selenite and selenium yeast on rumen fermentation parameters of Jinjiang cattle,compare the advantages and disadvantages of the two effects,and conduct in vitro fermentation test.The results indicate that:（1）The pH value of groupsⅲandⅱwas significantly lower than that ofⅰirradiation group（P<0.05）;There was no significant difference between groupⅲand groupⅱ;（2）The concentration of microbial protein in groupⅲwas significantly higher than that in groupⅰand groupⅱ（P<0.05）;（3）Groupsⅱandⅲhad no significant effects on gas production,ammonia-nitrogen concentration and IVD_MDof rumen fermentation of Jinjiang cattle（P>0.05）,（4）The GP and IVD_MD of groupsⅱandⅲwere slightly higher than those of groupⅰ,and the gas production and IVD_MD of groupⅲwere slightly higher than those of groupⅱ.The concentration of ammonia nitrogen was lower than that of the control group,but the difference was not significant（P>0.05）;（5）Compared with 0,the effects of VFAs in groupⅱand groupⅲwere significantly different except for isobutyric acid（P<0.05）;Compared with groupⅱ,the contents of acetic acid,propionic acid and total volatile fatty acids in groupⅲwere significantly increased（P<0.05）;TThe effect on isobutyric acid was not significant（P>0 0.05）.In conclusion,dietary supplementation of sodium selenite and selenium yeast can help in vitro rumen fermentation and improve the rumen environment of Jinjiang cattle;0.3 mg/kg selenium yeast was better than sodium selenite in the diet.Section 4 Comparison of Effects of Suitable Supplemental Doses of Na₂SeO₃and Selenium Yeast on Nutrient Digestibility,Blood Indexes and Rumen Microflora of Jinjiang Cattle（in vivo Test）.On the basis of experiment 3,the effects of appropriate supplemental doses of Na₂SeO₃and selenium yeast on nutrient digestibility,blood indexes and rumen microflora of Jinjiang cattle were studied by in vivo method.Three Jinjiang cattle with similar body weight（409±21）fitted with permanent fistulas were selected.3*3 Latin square design was adopted and divided into three groups:basal diet group（O）;Basal diet 0.3 mg/kg Na₂SeO₃group（A）;Basal diet add 0.3 mg/kg selenium yeast group（B）.The experimental period was divided into three periods,and the prefeeding period of 10 days was added before the start of each period（the turnover of trace elements in the animal body is slow）.The formal period was 16 days,and the blood,feces and rumen fluid samples of Jinjiang cattle were collected.The results indicate that:（1）The nutrient apparent digestion of Jinjiang cattle in groups A and B had no significant effects（P>0.05）.（2）The total antioxidant capacity and glutathione peroxidase in groups B and O were significantly increased（P<0.05）.Other antioxidant measures did not differ much（P>0.05）.（3）There was no significant difference in serum immune indexes of Jinjiang bovine IgG,IgM,IgA,IL-2,IL-6 and TNF-αin groups A and B compared with group O（P>0.05）.（4）The content of alkaline phosphatase in groups A and B was significantly lower than that in group 0（P<0.05）;Compared with group 0,groups A and B had no significant effects on other serum biochemical indexes of Jinjiang cattle（P>0.05）.（5）Group A and B had no significant effect on serum hormone indices of Jinjiang bovine（P>0.05）.（6）Compared with groups0 and A,rumen fluid pH of group B was significantly decreased（P<0.05）,and NH₃-N concentration was significantly increased（P<0.05）.Other rumen fermentation parameters had no significant difference（P>0.05）.（7）There is a big difference in the ACE index of rumen fluid between group A and group B（P<0.05）,but no differences in other indexes（P>0.05）.There was no significant difference in rumen chyme Chao and Ace index between A and B groups（P>0.05）.No difference in other indicators（P>0.05）.In rumen chyme,the XPB 1014 group of pilorucillaceae in group A was significantly higher than that in group B（P<0.05）,and there was no difference in the abundance of the top 10 bacteria in the other two groups.The results showed that 0.3mg/kg selenium yeast was better than Na₂SeO₃in the diet of Jinjiang cattle.Thus it can be seen,（1）dietary supplementation of Na₂SeO₃and selenium yeast has significant effects on rumen fermentation parameters of Jinjiang cattle,and can improve the antioxidant property of Jinjiang cattle,and improve the immune and other biochemical indexes.（2）dietary supplementation of selenium yeast has better effects than that of Na₂SeO₃.