The dietary cation-anion balance (DCAB) effect on the macromineral (Ca and P) balance, urinary and fecal pH, blood concentration of ionic and total calcium, as well as on the dry matter intake, was studied in four Holstein steers. Initially the animals were fed on a basal diet with +74.12 mEq/kg DM of DCAB. Further the diets were supplemented with ammonia sulfate to decrease the DCAB at the level of -154.84 mEq/kg DM. There were no differences (P>0.05) on fecal pH, phosphorus balance, as well as on ionic calcium concentration in function of time. The urine pH reduced significantly with the decrease of DCAB (P<0.01). No treatment differences (P>0.05) were observed for calcium balance, however, in the urine the calcium was higher for anionic diet. The serum total calcium concentration increased significantly (P<0.05) from the 19th day. Therefore, anionic diets with ammonia sulfate, offered in total mixed ration form had no effect in the DM ingestion. Besides, the urinary pH is an excellent indicative of the anionic diet efficacy and it took 19 days for an anionic diet of -154.84 mEq/kg DM to raise the total seric calcium levels in Holstein steers.
Steer; DCAB; calcium; phosphorus; dry matter intake; pH
