THE EFFECT OF 3 DISTINCT SEX-RATIOS AT 2 OESOPHAGOSTOMUM-DENTATUM WORM POPULATION-DENSITIES

Helminth-free donor pigs were inoculated with infective larvae of Oeso phagostomum dentatum. Five weeks later, the donor pigs were killed to recover the adult worms. By nonsurgical rectal transplantation, 6 grou ps of helminth-free recipient pigs were then given different female-to -male ratios (FMR) of O. dentatum worms (10% females [F], 50%F, 90%F) at either high (300 worms) or low (30 worms) doses. Fecal egg excretio ns were measured once weekly following transplantation until the pigs were killed 4 wt posttransplantation to assess the worm burdens and th eir location. There was a strong and significant correlation between n umbers of male and female worms located in the different sections of t he large intestine, suggesting that the worm sex as well as physiologi cal factors in the pig intestine may govern the location of the worms. There were no significant differences in fecal egg counts or female w orm fecundity between any of the groups. However at the low dose level , the female worm fecundity was markedly lower in the L10%F group than in the 2 other groups, thus suggesting for low worm densities an uppe r threshold for the FMR above which O. dentatum females produce fewer eggs.