Induction of lactic acidosis in cattle with sucrose: relationship between dose, rumen fluid pH and animal size.

To determine an efficient way to induce rumen lactic acidosis (rumen fluid pH 4.2 to 3.9 at 20 h after dosing), different dosages of sucrose on a basis of body weight (BW; 12 g/kg BW), metabolic weight (MW; 60 g/kg BW0.75 and corrected metabolic weight (CMW; y = 1057 + 43.1 BW0.75) were used in cattle of different size. In all cases rumen lactic acidosis occurred, although yearling steers given sucrose on a basis of BW had higher rumen fluid pH than yearlings given sucrose on a basis of MW and CMW. The heavier the yearlings given sucrose were (on a basis of BW and MW), the lower the rumen fluid pH. Bullocks given sucrose on a basis of BW and MW presented lower rumen fluid pH than those given sucrose on a basis of CMW. The heavier the bullocks given sucrose on a basis of BW and MW, the lower the rumen fluid pH. Only cattle given sucrose on a basis of CMW had a predictable rumen fluid pH within the desired range in both animal sizes. Larger cattle were more vulnerable to rumen lactic acidosis than smaller ones.