The effect of Induction of different levels of mild metabolic acidosis by anionic diet on mineral homeostasis and performance of transition Holstein dairy cows

The effects of different levels of mild metabolic acidosis by anionic diet on the performance of transition dairy cows were investegieted in 12 cows from 3 weeks (wk) before calving. One wk before calving, cows assigned to two groups according to urine pH (UpH) to recommended level (R UpH=6.2 to 7) and less than 6.3 (low UpH). The average prepartum urine pH was 6.7 and 5.8 for R UpH and low UpH groups, respectively (P<0.01). The prepartum serum concentration of Ca was not affected by the experimental groups, but significantly increased in the low UpH group within 2 h after calving. A trend was observed for higher serum concentration of phosphorus in the low UpH cows before calving. Although no significant difference was observed in prepartum DMI, but postpartum DMI and milk production were higher during wk 1 after calving in low UpH group (P<0.05). Total concentrations of protein and globulin were decreased on the day before calving in low UpH group. Also, after calving the concentrations of BUN, total protein, globulin, and milk protein were lower in this group of cows (P<0.05). Therefore, the induction of higher levels of metabolic acidosis in comparison to the recommended level before calving, can improve serum concentration of Ca and performance of transition cows.