Relationship of histamine in tissues and antiparasitic substances in gastrointestinal mucus to the development of resistance to trichostrongyle infections in young sheep.
The development of resistance to nematode infection and self-cure in a flock of young grazing sheep were examined in relation to changes in the levels of histamine in tissues and levels of antiparasitic substances in gastrointestinal mucus. Analysis of faecal egg counts showed that when the sheep were ranked according to individual mean monthly egg counts there was a significant trend to similar rankings in successive months. Sheep with high and low egg counts were slaughtered at monthly intervals for examination and comparison. Histamine levels in blood and intestinal content fluids were similar in both groups of sheep and were highest during maximum challenge by larval nematodes. Antiparasite activity of the intestinal mucus was significantly higher in sheep with low egg counts than those with high counts, between January and May, and was associated with significantly lower burdens of fourth stage larvae.
D000018:Abomasum / Q000378:metabolism; D000818:Animals; D005243:Feces / Q000469:parasitology; D006632:Histamine / Q000097:blood / Q000378:metabolism*; D007419:Intestinal Secretions / Q000276:immunology*; D007421:Intestine, Small / Q000378:metabolism; D009093:Mucus / Q000276:immunology*; D010270:Parasite Egg Count / Q000662:veterinary; D012621:Seasons; D012756:Sheep; D012757:Sheep Diseases / Q000276:immunology* / Q000469:parasitology; D013045:Species Specificity; D014251:Trichostrongyloidea / Q000276:immunology*; D014252:Trichostrongyloidiasis / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*
D006632:Histamine