PHYSIOLOGICAL AND BIOCHEMICAL RESPONSE OF THE DRAFT HORSE TO PLOWING IN RICE FIELDS

In order to determine the effort performed by crossbred draught horses in agricultural work, the biochemical and physiological response of f ive horses was evaluated after performing five hours of work (3 in the morning and 2 in the afternoon) with a 90 minutes break between the p eriods. Blood samples were obtained from the jugular vein with a vacut ainer. The haemoglobin concentration and globular volume were determin ed in whole blood. Lactic acid was determined in deproteinised blood, while cortisol and enzymatic activities were determined in plasma. Car diac and respiratory frequencies increased significantly with the work . These physiological variables were recovered 30 minutes post exercis e. Haemoglobin, globular volume, plasmatic cortisol and enzymatic acti vities of creatine kinases and aspartate aminotransferase increased si gnificantly during the exercise, but lactic dehidrogenase and lactic a cid presented no significant changes. The results showed that the musc ular effort performed by the horses was very intense, but this exercis e did not produce any evident injury or muscular fatigue on the animal s.