title: Multitrait indices to predict worm length and number in sheep with natural, mixed predominantly Teladorsagia circumcincta infection.
abstract: Accurately identifying resistance to gastrointestinal nematode infections requires the ability to identify animals with low and high intensities of infection. The pathogenic effects of nematodes depend upon both the length and number of worms, neither of which can be measured in live animals. Indices that predict these quantities are urgently needed. Monthly fecal egg counts, bodyweights, IgA concentrations and pepsinogen concentrations were measured on Scottish Blackface sheep naturally infected with a mixture of nematodes, predominantly Teladorsagia circumcincta. Worm number and average worm length were available on over 500 necropsied lambs. We derived predictive indices for worm length and number using linear combinations of traits measured in live animals. The correlations between the prediction values and the observed values were 0.55 for worm length and 0.51 for worm number. These indices can be used to identify the most resistance and susceptible lambs.
authors.affiliation: Institute of Biodiversity,Animal Health & Comparative Medicine,University of Glasgow,Bearsden Road,Glasgow G61 1QH,UK.
authors.forename: Colette
authors.initials: C
authors.lastname: Mair
authors.affiliation: Institute of Biodiversity,Animal Health & Comparative Medicine,University of Glasgow,Bearsden Road,Glasgow G61 1QH,UK.
authors.forename: Louise
authors.initials: L
authors.lastname: Matthews
authors.affiliation: Institute of Biodiversity,Animal Health & Comparative Medicine,University of Glasgow,Bearsden Road,Glasgow G61 1QH,UK.
authors.forename: Joaquin Prada J
authors.initials: JP
authors.lastname: De Cisneros
authors.affiliation: Institute of Biodiversity,Animal Health & Comparative Medicine,University of Glasgow,Bearsden Road,Glasgow G61 1QH,UK.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Stefan
authors.affiliation: Institute of Biodiversity,Animal Health & Comparative Medicine,University of Glasgow,Bearsden Road,Glasgow G61 1QH,UK.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Stear
mesh_terms: D000818:Animals; D001835:Body Weight; D005243:Feces / Q000469:parasitology; D007070:Immunoglobulin A / Q000097:blood; D015999:Multivariate Analysis; D009348:Nematoda / Q000033:anatomy & histology* / Q000502:physiology; D009349:Nematode Infections / Q000469:parasitology / Q000662:veterinary*; D010270:Parasite Egg Count; D020116:Pepsinogen A / Q000097:blood; D012756:Sheep; D012757:Sheep Diseases / Q000469:parasitology*
chemical_list: D007070:Immunoglobulin A; D020116:Pepsinogen A
keywords: predictive index