The effect of monensin against swine dysentery.

The use of monensin sodium against naturally transmitted swine dysentery was evaluated in 4-week-old piglets, with an average weight of 8 kg, over a period of 112 days. Three treatments were compared using between two and four pens per treatment and 12 pigs per pen. Monensin was administered via the feed, either immediately post weaning to four pens of pigs (T1), or after 12 days (T2, two pens). The T1 group received monensin at the rate of 100 ppm (days 0-56), 50 ppm (days 57-84) and 25 ppm until the end of the trial. In the other group monensin was given at 100 ppm (days 12-84) and at 50 ppm (days 85-112). Unmedicated feed was given to two pens (T3). The continuous administration of monensin from weaning was effective in the control or prevention of swine dysentery. A significant (P less than 0.05) improvement, in comparison with the other two groups, was observed in terms of mortality, diarrhoea score, average daily gain (ADG) and feed conversion ratio (FCR). There was a reduction in mortality, diarrhoea score/days and an improvement in growth performance parameters in pigs treated with monensin after the disease had been established, with ADG and FCR values significantly (P less than 0.05) different compared with the untreated controls.