Régulation des populations de Nématodes gastro-intestinaux ...

3. RESULTS
3.1. Dynamics of the worm population (Table 4)
Résultats
No worm and no egg excretion were recorded in uninfected control lambs during the
whole experiment. All lambs challenges were followed by a worm establishment with
efficiency rates ranging from 3% to 85% (mean 40%) ; a high individual variability among
total worm counts was observed within each group but no differences in the total worm
burdens were observed between the groups A and B. Furthermore, the development of worms
was similar in the two infected groups : only fourth-stage larvae (L4) were recovered at 4 days
post challenge (dpc) ; a majority of immature forms were present at 10 dpc ; a majority of
adult worms were observed at 17 dpc and almost only adult worms at 28 dpc. Nevertheless at
10 dpc, one lamb of group A harboured few adult worms.
Some differences were observed in faecal egg output between both infected groups. At
17 dpc, three lambs of the primary-infected group, but none of the previously-infected sheep,
shed egg in their faeces. At the end of the experiment (28 dpc), all lambs of groups A and B
shed eggs in their faeces but the difference between these two groups in egg excretion was
statistically significant (395 +/- 360 versus 795 +/- 272 for groups A and B respectively,
P