In order to compare the susceptibility to acute rumen lactic acidosis (RLA), four Jersey (J) (Bos taurus) and four Gir (G) (Bos indicus) steers were used to evaluate the degree of metabolic acidosis (MA) and the metabolism of L-lactate during the RLA. The RLA was induced by the administration of sucrose into the rumen. Blood samples were collected at following times: zero, 14th,16th, 18th, 20th, 22nd and 24th h. Total lactic acid and its isomers, and blood gas determination were measured. At the most critical moments (14th to 18th h) the MA was severe in both breeds, but the MA became moderate in the G steers and remained severe in the J steers at the end of the trial. Higher amounts of D-lactate was absorbed from the rumen to the blood of the J steers; the higher the D-lactate plasma level, the lower the blood pH in this breed (r = - 0.78). Conversely, L-lactate was more absorbed and metabolised in the G steers promoting a partial recovery of the acid-basic homeostasis, as measured by the pO2 and pCO2 changes. The Bos indicus steers were less susceptible to metabolic acidosis than the Bos taurus steers.
cattle; breeds; susceptibility; metabolic acidosis; lactate
