| This experiment has investigated the effection of addition different concentration of magnesium salt to anionic diets to the production performance and blood.The motive was to discover suitable concentration of magnesium salt,to provide thereunder for further investigation on cow puerperal fever of dairy cows.24 Holsteins were divided into four groups stochastically,one control group and A,B,C three treated groups.They were assigned to treatments by fed the diets with DCAD numerical valuing +98.64 meq/kgDM;-110.96meq/kgDM which added ammonium chloride 100g,ammonium sulfate 75g,magnesium sulfate 12.73g;-110.96meq/kgDM which added ammonium chloride 100g,ammonium sulfate 50g,magnesium sulfate 45.45g; -110.96meq/kgDM which added ammonium chloride 100g,magnesium sulfate 90.90g.The other main nutrient index(CP,NND,Ca,P) almost had no difference among diets.Mensurate each group of cow perinatal urine PH value,blood serum calcium(Ca), blood serum magnesium(Mg),the blood serum hydroxyproline and the blood serum parathyroid element(PTH) change,observe the occurence of disease.The result indicated that:1.the cows'serum calcium value of the control group was lower than the treated group during pre-natal and post-natal,with average content 1.36±0.30*10-3mol/l,which was at sub-clinical low blood calcium condition(normal value was generally 1.80-3.00*10-3mol/l).Compared with A group,B group and C group,the control group reduced 29.17%,38.74%and 28.42%separately.There was no remarkable difference between A group of and C group(P＞0.05).The blood serum calcium of A group was in normal range,The blood serum calcium of C group was lower than 1.80*10-3mol/l on the procreation day,other times were in the normal level.The blood calcium reduced suddenly on the procreation day,the curve change scope was big,the stress responds was in a big way,overall effect was worse than A group.B group's mean value content and various times blood serum calcium value all was higher than other groups(mean value content compared to control group,A group and C group elevated 63.24%,15.63%and 16.84% separately),and was higher extremely than the control group on the procreation day(P＜0.0 1),the curve change scope was small,B group's overall effect was best.2.Each group's blood serum magnesium elevated gradually before procreation,but the change scope was small.The blood serum magnesium droped gradually,but the treated group was higher than the control group.Compared with A group,B group and C group,the value of the control group's blood serum magnesium reduced 5.21%,11.65%and 12.50%separately,and was lower than the normal value slightly.A group's blood serum magnesium content was in the normal range,B group and C group's blood serum magnesium content was higher than other group in various times obviously(P＜0.05). The difference between the control group and A group was not remarkable(P＞0.05).3.The content of the blood serum hydroxyproline of the control group was lowest,reduced 26.32%,43.59%and 4.94%compared to that of A group,B group and C group separately. The content of the blood serum hydroxyproline of each group was not different remarkable on the 14th day and 7th day before procreation,and the 7th after procreation,the 3th day before procreation was lowest,was lower obviously than that of B group,was extremely lower than that of C group(P＜0.01).The average content of A group was higher obviously than that of the control group,the average content of B group was extremely higher than other groups(P＜0.01).The range of variation was big between A group's blood serum hydroxyproline content before procreation and after procreation,other groups' change was consistent,the change scope was small,the content fell to the lowest on the procreation day,then elevated gradually,but the content of B group was higher than other groups all the time.4.The average content of the parathyroid hormone(PTH) of the control group was highest,elevated 199.32%,273.50%and 217.09%separately,compared to that of A group,B group and C group,there was no remarkable difference between that of the control group and B group(P＞0.05),the control group and B group was extremely higher than A group and C group(P＜0.01),the difference between A group and C group was not remarkable(P＞0.05).The difference of PTH's content between before procreation and after procreation was remarkable(P＜0.05).On the 7th day after procreation,the PTH's content of the control group was higher remarkablely than that of A group,and was higher extremely on other pHases(P＜0.01).the PTH's content of C group was lower than B group on the 7th day before procreation,on the third and 14th day after procreation.There was no remarkable difference between C group and B group on the 14th day before procreation.on the 3th before procreation,on the procreation day and on the 7th day after procreation (P＞0.05).there was no remarkable differencebetween A group and C group on all pHases(P＞0.05).The PTH's content of B group and C group elevated from pre-natal 14th days to the procreation day,then reduced gradually.The control group and A group reached highest on the procreation day,reduced gradually afterward,then tend to hoist on the 7th day.5.The clinical puerperal fever rate was 33.33%in the control group,The clinical puerperal fever rate was 16.67%in the A and C group,We have not observed the clinical puerperal fever in B group.The placenta detention rate was 33.33%in the control group,but the treated groups were only 5.56%.
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