Effect of Monensin in Ameuorating Subacute Lactic Acidosis in Buffalo Calves

Ahuja A. K., S. S. Randhawa, S. S. Rathor: Effect of Monensin in Ameliorating Subacute Lactic Acidosis in Buffalo Calves. Acta vet. Bmo, 59, 1990: 171-178. The efficacy of monensin feeding on rumen metabolism, acid base status and gas tension of blood in molasses induced subacute lactic acidosis in buffalo-calves was evaluated. Subacute lactic acidosis was induced by oral administration of molasses at a dose 10 g/kg body mass as a single dose. Monensin was found to be effective in improving rumen liquor pH and significantly decreasing the lactic acid content of rumen liquor. The total volatile fatty acid (TVFA) concentration and their individual proportion was not affected following administration of first dose of monensin at 12 h after experimental induction. However, administration of second dose at 24 h resulted in marked increase in the concentration of TVFA associated with decrease in the ruminal acetate and butyrate production and proportionate increase in the ruminal propionate concentration. The blood lactic acid content also showed a significant decline in the monensin treated group indicating its efficacy also in combatting developing systemic acidosis as reflected by improvement in the actual bicarbonate, standard bicarbonate, acid base excess and bicarbonate to carbonic acid ratio following acid-base analysis of the venous blood. Rumen acidosis, Ionophore antibiotic, acid base status, rumen metabolism It has been demonstrated that growth of major lactate producing bacteria Streptococcus bovis and Lactobacillus spp. is inhibited by the antibiotic monensis (Dennis et al. 1981a). This antibiotic also helps in lowering the lactic acid content in the in vitro rumen fermentations (Nagaraja et al. 1981). Selective inhibition of major lactate producing bacteria by monensis in vitro suggests its potential use in controlling lactic acidosis in ruminants. The objective of this study was, therefore, to test the efficacy of monensin feeding on rumen metabolism and acid-base status of blood under molasses induced subacute lactic acidosis in buffalo calves. Materials and Methods The experiment was carried out on four Murrah buffalo calves of about one year age. Three of the calves were placed on monensin treatment and the fourth was kept as control. After an overnight fasting subacute lactic acidosis was induced in all the calves by oral feeding of molasses at a dose 10 g/kg body mass as a single dose. After the induction of acidosis, the first dose of monensin was given orally at a dose 3 mg/kg body mass after 12 h of induction and the same dose repeated 24 h after induction. Ruminal and blood samples were collected every 6 h from 0 to 24, then every 12 h from 24 to 48 h. Rumen liquor samples treated with 0.5 ml of saturated mercuric chloride were collected via ruminal cannulae and the pH determined immediately. Before each collection, blood samples were drawn into heparinized syringes for analysis of acid-base status and blood gas tensions by blood gas analyser (Radiometer, Copenhagen, Denmark). The rumen liquor samples were. analysed for lactic acid by the method of Barker (1961). Ammonia-N (NHa-N) was analysed by the micro diffusion technique (Conway 1957). Total volatile fatty acids were analysed according to the method of Annison (1954) and molar proportion of individual fatty acids by gas chromatography (Bernard and Boucque 1968).