The Effects Of Anionic Salts And Vitamin D On Periparturient Dairy Cow's Ca Regulation And Health

Six trials were conducted to study the effect of dietary anionic salts and vitamin D on acid base balance, blood-ions metabolism, responsiveness to Ca related hormones and enzyme, immune function in peripartum cows. Furthermore, the mechanism of anionic salts on rumen fermentation was examined by using artificial rumen system and dairy cows fitted with permanent rumen canulas.Trial 1 studied the effects of dietary anionic salts on blood acid base and ions, urinary ions exeretion in prepartum cows. The treatment diet with -100 DCAD dietary significantly effected blood acid base status (P<0.05). Its HCO₃^- and BE were significant decreased when compared with the control diet with +100 DCAD (P<0.05). The treatment supplemented with anionic salts can significantly increase blood-ionized calcium and chlorine concentration (P<0.05), but not effect other ions in serum(p>0.05). Metabolism acidosis was induced in the prepartum cow fed anionic salts, which showed significantly low urinary pH (P<0.05), and high calcium and chlorine excretion in urine (P<0.05). The treatment had no significantly effect on the other ions in urinary excretion (P>0.05).Trial 2 and trial 3 were conducted to study the effects of different dose of anionic salts in diet on the rumen fermentation. Feeding the diet with -150 DCAD decrease pH and increased NH₃-N concentration both in artificial rumen and dry cow's rumen during 2 to 6 hours compared with control group(P<0.05), The diet with -150 DCAD group also decreased the acetic acid to propionic acid ratio in artificial rumen compared with control group (P<0.05), but not in dairy cows. The cellulytic enzyme activity was not affected by different anionic salt concentration (P>0.05).Trial 4 was designed to study the effects of anionic salt and vitamin D in diet on blood-ions and to Ca related hormones and enzymes. The results showed that the groups with anionic salts can increased the chlorine ion concentration and decreased the PTH concentration in serum (P<0.05) before 7 days of calving and on the calving day. On the calving day the treatments with anionic salts significantly increased the hydroxyproline and magnesium ion concentration in serum (P<0.05), and also increase the serum vitamin D concentration.Trial 5 was used to study the effects of anionic salt and vitamin D in diet on the serum concentration of stress related hormones, expressing level of HSPs in PMBC, and the immune function of peripartum cows. The results showed that anionic salts treatment increased serum TP concentration between pre-7 days and post-7 day of the calving day (P<0.05), improved COR level on the calving day (P<0.05). The expressing levels of HSP70 and HSP90 increased obvovisly on the calving day compared to pre-7 days of calving (P<0.05), but decreased after calving. There was not difference for HSPs expressing level among treatments (P>0.05). The number of CD3⁺CD4⁺T cells and CD3⁺CD8⁺T cells were all greatly reduced in periparturient period. But dietary anionic salts and vitamin D improved it, and the effect of dietary vitamin D was more effective than anionic salts.Trial 6 was used to study the effects of anionic salts and vitamin D in dietary on blood metabolism parameters, dairy cow performance and health. The group with anionic salts significantly increased thethe BUN concentration in serum (PO.05). Anionic salt diets trended to increase the standard milk yield (P>0.05), But decreased somatic cell count significantly (PO.05), and reduced the severity of udder edema and incidence of retained placenta.In conclusion, dietary anionic salts can manipulate body Ca balance through its effect on body acid base metabolism. The mechanism of the prevention of blood Ca decline when prepartum cows are fed anionic salts is that the rate of bone Ca mobilization is increased directly. The immune function of the peripartum cows can be improved by supplementing vitamin D in the diet.