Effects Of Dietary Cation-Anion Difference On Ca Utilization And Health Condition Of Transitional Cows

Twenty Holsteins were blocked and assigned randomly to treatments of +89.43, -53.75, -106.96, -150.07meq[(Na++K+)-(Cl^-+S^2-)]/Kg of DM dietary.The first was control group,the others were treatment groups.The other main nutrient index (CP, P, ME) almost had no difference among diets.The objective of this study was to examine the inflence of dietary cation-anion differnce (DCAD) on serum Ca, P, PTH, CT and oxyptoline concentration, the apparent digestibility of Ca and P , the variation of Ca and in milk and the ocurrence of disease.The results indicated that the serum Ca, CT, AKP and oxyptoline concentrations increased and pH in urine declined with DCAD decreasing.The total average Ca concentrations in treatment groups were significantly higher than that of control group(p<0.01).In group A, B and C,it promoted by 47%, 71%and 48% than that of control group respectively.But in control group it declined by 27%-56% than normal value and the cows were in subclinical hypocalcaemia condition all along(normal value is generally 1.80-3.10mmol/l).The curve of it fluctuated markedly and parturient serum Ca concentration decreased dramanticaly.The total average Ca concentration in group B improved by 71%, 17% and 15% than that of contol group, group A and B respectively,It was exetremly higher than those in the other groups(p<0.01) and the curve of it was equable pre-and-post calving,the DCAD was optimum. The total average Ca concentration had no significant difference between group A and C(p>0.05).The sernm P concentrations were not affected by supplementing the diet of dry cows with anionic additive,which maitained normal(normal value is generally 1.06-3.09mmol/l),and it decreased to the lowest on the first day precalving and later gradually increased. The total PTH average concentration in control group was the highest, which had no significant difference with group B (p>0.05) and increased by 220%, 22% and 236% than that of group A, B and Crespectively,both of them were exetremely higher than those of the other two groups(p<0.01).The total PTH average concentration had no significant difference between group A and C(p>0.05).But the total average Ca concentration in control group was the lowest, which declined 32% 42% and 33% than that of group A B and C respectively.The total CT average concentration in control group was the lowest, which had no significant difference with group A (p>0.05) and declined 8% 36% and 39% than group A B and C respectively,But they both were much lower than those of the other two groups(p<0.01).The total average AKP concentration in group C was the highest , which was exetremely higher than those of control group and group A (p<0.01),and had no significant difference with group B. The total average AKP concentration in group A was significantly lower than that of the others. The oxyptoline concentrations in all groups were in negatively correlation to Ca.The total average oxyptoline concentration in B group was the highest, which was in siginificantly correlation to Ca(p<0. 01). Control group was the lowest.which declined by 7% 77% and 32% than that of group A, B and C respectively. In treatment groups the apparent digestibility of Ca and P the average yield of milk also increased with DCAD decreasing. But the Ca and P concentrations in the milk were unaffected by adding anionic additive to the diet. The incidence of retained Placenta in control group and treatment groups were 20% and 7% respectively,the former declined by 65% than the latter.