Impact of the post-weaning parasitism history on an experimental [i]Haemonchus contortus[/i] infection in Creole goat kids
Résumé
Gastrointestinal nematode (GIN) infections have an important negative impact on small
ruminant production. The selection of genotypes resistant to these parasitic infections is a
promising alternative control strategy. Thus, resistance against GIN is an important component
of small ruminant breeding schemes, based on phenotypic measurements of resistance
in immune mature infected animals. In this study we evaluated both the impact of the
post-weaning parasitism history on the response to an experimental Haemonchus contortus
infection of resistant and susceptible Creole kids chosen on the basis of their estimated
breeding value, and the interaction with the kid’s genetic status. During the post-weaning
period (from 3 months until 7 months of age) Creole kids were reared at pasture according
to four different levels of a mixed rotational stocking system with Creole cattle: 100% (control),
75% (GG75), 50% (GG50), and 25% (GG25) of the total stocking rate of the pasture. The
level of infection of the kids decreased significantly at 50% and 25% of the total stocking rate.
After the post-weaning period at pasture, at 11 months of age kids were experimentally
infected with H. contortus. The faecal egg counts (FEC) were significantly lower in the groups
showing the highest FEC at pasture. This result suggests that a degree of protection against
an experimental H. contortus infection occurred during the post-weaning period and was
dependant on the level of parasitism. Interestingly, no interaction was observed between
this level of protection and the genetic status. In conclusion, the level of post-weaning natural
parasitism history at pasture would not influence the genetic status evaluation. More
generally our results suggest that it would be better to expose kids to a high level of gastrointestinal
parasitism during the post-weaning period in order to increase the basal level
of resistance thereafter.
Domaines
Sciences du Vivant [q-bio]
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