title: Negative covariance between parasite load and body condition in a population of feral horses.
abstract: In wild and domestic animals, gastrointestinal parasites can have significant impacts on host development, condition, health, reproduction and longevity. Improving our understanding of the causes and consequences of individual-level variation in parasite load is therefore of prime interest. Here we investigated the relationship between strongyle fecal egg count (FEC) and body condition in a unique, naturalized population of horses that has never been exposed to anthelmintic drugs (Sable Island, Nova Scotia, Canada). We first quantified variation in FEC and condition for 447 individuals according to intrinsic (sex, age, reproductive status, social status) and extrinsic (group size, location, local density) variables. We then quantified the repeatability of measurements obtained over a field season and tested for covariance between FEC and condition. FECs were high relative to other horse populations (mean eggs per gram ± SD = 1543·28 ± 209·94). FECs generally decreased with age, were higher in lactating vs non-lactating females, and unexpectedly lower in males in some part of the island. FECs and condition were both spatially structured, with patterns depending on age, sex and reproductive status. FECs and condition were both repeatable. Most notably, FECs and condition were negatively correlated, especially in adult females.
authors.affiliation: Department of Biology,University of Saskatchewan,112 Science Place, Saskatoon, SK S7N 5E2,Canada.
authors.forename: Lucie
authors.identifier: 0000-0003-0019-125X
authors.initials: L
authors.lastname: Debeffe
authors.affiliation: Department of Biology,University of Saskatchewan,112 Science Place, Saskatoon, SK S7N 5E2,Canada.
authors.forename: Philip D
authors.initials: PD
authors.lastname: McLoughlin
authors.affiliation: Department of Biology,University of Saskatchewan,112 Science Place, Saskatoon, SK S7N 5E2,Canada.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Medill
authors.affiliation: Department of Biology,University of Saskatchewan,112 Science Place, Saskatoon, SK S7N 5E2,Canada.
authors.forename: Kathrine
authors.initials: K
authors.lastname: Stewart
authors.affiliation: Department of Biology,University of Saskatchewan,112 Science Place, Saskatoon, SK S7N 5E2,Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Andres
authors.affiliation: Parks Canada Agency,52 Campus Drive,Saskatoon SK S7N 5B4,Canada.
authors.forename: Todd
authors.initials: T
authors.lastname: Shury
authors.affiliation: Department of Veterinary Microbiology,University of Saskatchewan,52 Campus drive,Saskatoon,SK S7N 5B4,Canada.
authors.forename: Brent
authors.initials: B
authors.lastname: Wagner
authors.affiliation: Department of Veterinary Microbiology,University of Saskatchewan,52 Campus drive,Saskatoon,SK S7N 5B4,Canada.
authors.forename: Emily
authors.initials: E
authors.lastname: Jenkins
authors.affiliation: Department of Comparative Biology and Experimental Medicine,University of Calgary,3330 Hospital Drive,Calgary,AB T2N 4N1,Canada.
authors.forename: John S
authors.initials: JS
authors.lastname: Gilleard
authors.affiliation: Department of Comparative Biology and Experimental Medicine,University of Calgary,3330 Hospital Drive,Calgary,AB T2N 4N1,Canada.
authors.forename: Jocelyn
authors.initials: J
authors.lastname: Poissant
mesh_terms: D000367:Age Factors; D000818:Animals; D002170:Canada; D005243:Feces / Q000469:parasitology; D005260:Female; D006734:Horse Diseases / Q000469:parasitology*; D006736:Horses / Q000469:parasitology*; D006790:Host-Parasite Interactions; D008297:Male; D010270:Parasite Egg Count / Q000662:veterinary; D059208:Parasite Load; D012621:Seasons; D012737:Sex Factors; D013319:Strongyle Infections, Equine / Q000469:parasitology*; D013323:Strongylus / Q000302:isolation & purification* / Q000502:physiology
keywords: gastrointestinal parasite; mammal; nematode; repeatability; strongyle; ungulate; wild population