A STUDY ON THE TRANSMISSION OF OESOPHAGOSTOMUM-DENTATUM AND HYOSTRONGYLUS-RUBIDUS AMONG OUTDOOR REARED PIGS IN DENMARK

This study was carried out to obtain basic information on the transmis sion of Oesophagostomum dentatum and Hyostrongylus rubidus in outdoor reared pigs in Denmark. Eighteen 10 weeks old worm-free pigs were allo cated into 3 groups of 6 pigs each. In May, all pigs were turned out o n the same parasitologically naive pasture, and after 2 weeks the pigs in groups 2 and 3 were experimentally infected with 10,800 O. dentatu m and 8,700 H. rubidus infective larvae, respectively. Pigs in group 1 served as non-infected controls. All pigs were reared together on the experimental pasture for further 134 days until slaughter in October. Strongyle egg counts, differentiation of infective larvae at species level, serum pepsinogen, and herbage larval infectivity were monitored at regular intervals throughout. Both strongyle species established i n the originally parasite-free pigs (group 1) and cross infections wer e established in group 2 and 3. The pigs were exposed to steadily incr easing herbage infectivity of both species of strongyles. At the end o f the experiment, geometric mean worm burdens of O. dentatum in groups 1, 2 and 3 were 1202, 6136 and 1431 respectively, the burden in group 2 being significantly higher (p<0.05) than that of the 2 other groups . The geometric mean worm burdens of H. rubidus in groups 1, 2 and 3 w ere 4907, 3679 and 5246 respectively, showing no significant differenc es between groups.