The response of breeding doses to nematodiasis: segregation into "responders" and "non-responders".
Responder and non-responder does were identified from a flock of 95 Scottish cashmere 2-6 year-old does exposed to natural nematode infection over a 12-month period. Every 5 weeks, the does were faecal sampled for worm-egg counts prior to anthelmintic treatment. Responsive and non-responsive individuals were identified on the basis of their cumulative faecal egg count (FEC) rankings: the 8 lowest and 8 highest rankings were deemed to be responders and non-responders, respectively. Retrospective analysis showed that the mean egg count of the 8 responders was significantly lower than that of the 8 non-responders. The selected responders and non-responders were subsequently housed together with 8 randomly selected does from a control line, and given a mixed trickle challenge with Teladorsagia circumcincta and Trichostrongylus vitrinus larvae (L3). Mean responders FEC was significantly lower following artificial infection than that of non-responder and unselected does. Peripheral eosinophilia was significantly greater in responders in the first 3 weeks of this infection. On day 60, the infection was terminated with anthelmintic and 7 days later the goats were given a single challenge of 50,000 T. circumcincta L3. The mean responder worm burden was lower, and exhibited greater evidence of retardation of worm development, than those of non-responder and unselected does. Responders had significantly more mast cells and globule leukocytes post-challenge than did the other 2 groups. These results suggest that under the conditions encountered in this experiment, it is possible to segregate goats into responders and non-responders using simple parasitological criteria, as individual responsiveness is a relatively repeatable phenomenon.
Patterson
D M
DM
Moredun Research Institute, Edinburgh, U.K.
Jackson
F
F
Huntley
J F
JF
Stevenson
L M
LM
Jones
D G
DG
Jackson
E
E
Russel
A J
AJ
D000821:Animal Feed; D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use*; D001947:Breeding; D005273:Fenbendazole / Q000627:therapeutic use*; D015511:Goat Diseases; D006041:Goats / Q000469:parasitology / Q000502:physiology*; D007814:Larva; D007958:Leukocyte Count; D010270:Parasite Egg Count; D012606:Scotland; D012621:Seasons; D014251:Trichostrongyloidea / Q000302:isolation & purification*; D014252:Trichostrongyloidiasis / Q000503:physiopathology / Q000517:prevention & control / Q000662:veterinary*; D014253:Trichostrongylosis / Q000503:physiopathology / Q000517:prevention & control / Q000662:veterinary; D014254:Trichostrongylus / Q000302:isolation & purification*
D000871:Anthelmintics; D005273:Fenbendazole