SummaryGenetic resistance to gastrointestinal worms is a complex trait of great importance in both livestock and humans. In order to gain insights into the genetic architecture of this trait, a mixed breed population of sheep was artificially infected with Trichostrongylus colubriformis (n=3326) and then Haemonchus contortus (n=2669) to measure faecal worm egg count (WEC). The population was ge...

Rates of production and oxidation of ruminal acetate were measured in young sheep (1) infected with T. colubriformis; (2) kept worm-free and pair-fed to (1); and (3) kept worm-free and given feed ad lib. Both voluntary food consumption and the production rate of acetate were reduced by up to 76 per cent in sheep on treatment (1) compared with (3). Acetate production rate was 30 per cent lower i...

A stock of Trichostrongylus colubriformis infective larvae (L3) was stored for up to 15 weeks at 24 degrees C. At three weeks intervals, samples of L3 were taken to assess exsheathment rate and enzyme activity Leucine Amino Peptidase (LAP) and Alkaline Phosphatase (AP). From 0 to 9 weeks of storage, a decrease in enzyme activity was observed correlated with a decrease in exsheathment rate (perc...

This study investigated the gastrointestinal parasitism by helminths and protozoa in sheep (Ovis aries) Santa Inês breed, municipality of Lajes, Rio Grande do Norte. Monthly, from April 2005 to August 2007, stool samples were collected from two tracer lambs in the first day of the experiment and performed a necropsy of these animals in 44th day. A total of 64 lambs were sampled, but only 62 lam...

Trichostrongylids infection has gained significant public health importance since Trichostrongylus spp. infections have been reported in humans in Lao PDR. In this study, gastrointestinal nematodes were identified and the intensity of infections was determined in goats and cattle, which are animals greatly used for meat production in Lahanam Village, Lao PDR. The total number of goats and bovin...

Background: It is necessary to identify phenotypic traits related to natural resistance against gastrointestinal nematodes (GIN) in order to know the host immunity status in productive ewes. Objetive: To determine haematological and immunological parameters (IgA and IgG) during pregnancy and lactation in Blackbelly ewes naturally infected with GIN. Methods: The number of eggs per gram (EPG), pa...

This study aimed to identify putative quantitative trait loci (QTL) that significantly affect internal parasite resistance in a backcross sheep population. A Romney x Merino backcross (to Merino) flock was challenged in 3 separate infections with Trichostrongylus colubriformis (primary and secondary) and Haemonchus contortus (tertiary). Haematological parameters were measured and faecal worm eg...