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Avilamycin, an oligosaccharide antibiotic with growth-promoting properties in pigs, has proved to be effective in controlling stress-induced post-weaning diarrhoea in piglets, caused mainly by Escherichia coli. The present study includes two trials, in which 400 newly-weaned piglets were used (200/trial). The following five different treatments were tested; 0, 40 and 80 p.p.m. avilamycin, 50 p.p.m. olaquindox and 100 p.p.m. apramycin. In each trial there were four pens (each with five females and five males) per treatment. Avilamycin when given at 80 p.p.m. reduced average daily diarrhoea score (ADDS) and mortality, and improved liveweight gain and feed conversion ratio (FCR), compared with the untreated controls, the 40 p.p.m. avilamycin and the 50 p.p.m. olaquindox (P less than 0.05) treatments. The overall performance of 40 p.p.m. avilamycin and 50 p.p.m. olaquindox was similar. The results indicate that avilamycin at the dose level of 80 p.p.m. in the starter feed can control post-weaning diarrhoea of piglets and prevent loss of productivity. Nevertheless, the antibiotic apramycin, whose spectrum of activity is mainly against the Gram-negative bacteria, given at the therapeutic level of 100 p.p.m., was more effective than any other experimental treatment (P less than 0.05), except for ADDS and FCR which were not significantly different from that of avilamycin 80 p.p.m.

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.

Social and environmental stressors during the critical period of weaning frequently affect not only performance but also the health status of piglets. Pigs unable to cope with the changes associated with weaning develop a condition characterized by slowing of growth and a listless or unthrifty appearance, known as the wasting pig syndrome (WPS). In the present investigation a total of 100 4-week-old wasting pigs were studied. The pigs were divided randomly into 10 pens (10 animals per pen). Half the number of pigs were treated orally with amperozide (2.5 mg/kg body-weight), a psychotropic drug shown to modify emotional behaviour in response to social stress. Control groups were treated with long-acting oxytetracycline and vitamins (A + D3 + E). There were significant improvements in average daily weight gain (P less than 0.05) and feed conversion ratio (P less than 0.01) in amperozide-treated pigs compared with controls. Furthermore, there was a significant reduction (P less than 0.05) in mortality in amperozide treated groups. Within 2 weeks following amperozide treatment the clinical signs of the WPS had disappeared and the pigs grew at the same rate as normal healthy pigs.