resistance of st. croix lambs to haemonchus contortus in experimentally and naturally acquired infections.parasitological and immunological parameters of experimental or naturally acquired infections with haemonchus contortus were compared in st. croix and dorset lambs. in experimental infections, st. croix lambs developed significantly greater levels of resistance to h. contortus, following primary exposure, as compared with dorset lambs. this resistance was influenced both by age and by prior exposure to parasites. in grazing experiments on h. contortus-infected pasture, st. croix lambs shed signi ...19921502784
experimental haemonchus contortus infection in three breeds of sheep.nine- to 10-month-old florida native, st. croix and dorset/rambouillet sheep were infected with haemonchus contortus. the primary infection was terminated by anthelmintic treatment 9 weeks later and animals were then reinfected with h. contortus. dorset/rambouillet sheep showed higher fecal egg counts and decreased packed cell volumes and plasma protein levels compared with the other two breeds during the primary infection. however, no breed differences were found in total worm burdens in either ...19902399644
alveolar mastocytosis and eosinophilia in lambs with naturally acquired nematode infections of protostrongylus rufescens and haemonchus contortus.specific-pathogen-free dorset and st. croix lambs were placed on pasture contaminated with haemonchus contortus third stage larvae and slugs carrying third stage larvae of protostrongylus rufescens for an entire grazing season to evaluate breed differences in acquired resistance to these nematodes. lambs were evaluated for clinical signs, clinical pathology and histopathologic lesions associated with these infections. both breeds acquired natural infections with h. contortus and lungworm when al ...19958746699
peri-parturient rise in faecal strongyle egg counts of different genotypes of sheep in north sumatra, indonesia.faecal strongyle egg counts were monitored in peri-parturient ewes and dry ewes grazing in a rubber plantation in north sumatra, indonesia. a significant rise in faecal egg counts was observed during the post-parturient period. haemonchus contortus was the dominant species in the faecal cultures of the lactating ewes. the intensity of the peri-parturient rise was affected by the genotype of the sheep, which were the local sumatra and its f1 crosses with st. croix, barbados blackbelly and java fa ...19979066065
relative resistance of dorper crossbred ewes to gastrointestinal nematode infection compared with st. croix and katahdin ewes in the southeastern united states.a study was conducted to evaluate relative resistance of dorper crossbred (do), katahdin (ka), st. croix (sc), and hampshire (ha) ewes to natural and experimental gastro-intestinal (gi) nematode infection over a 20-month period. the objective of experiment 1 was to evaluate breeds for resistance to infection acquired naturally from mixed grass pastures. in year 1 (may-december 2000) de-worming of ewes occurred during wet, hot conditions in july and during late pregnancy in december. in year 2 (j ...200212423938
performance of hair sheep composite breeds: resistance of lambs to haemonchus contortus.this study was designed to evaluate breed differences in resistance to haemonchus contortus in lambs. a total of 181 ewe lambs representing crossbred dorsets (do) and dorpers (dp; out of 1/2-dorset, 1/4-rambouillet, 1/4-finnsheep ewes) and straight-bred katahdins (kt) were evaluated over 3 yr. an additional 144 do, dp, kt, and barbados blackbelly x st. croix (hh) wethers were evaluated over 2 yr. lambs were weaned at 60 to 90 d of age. after deworming at about 4 mo of age, ewe lambs received app ...200414974560
prevalence of anthelmintic resistance on sheep and goat farms in the southeastern united determine prevalence of anthelmintic resistance on sheep and goat farms in the southeastern united states.200819072608
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