title: Maintenance of acquired immunity to Trichostrongylus colubriformis in Merino sheep that are losing weight.
abstract: The effect of loss of weight on maintenance of acquired immunity to Trichostrongylus colubriformis in Merino sheep was assessed in 2 experiments. Adult Merino sheep with previously acquired immunity to T colubriformis were housed in individual pens. Sheep were infected 3 times weekly with 2000 T colubriformis larvae. A diet based on chopped oaten and lucerne hay (experiment 1) or a pelleted diet based on lucerne hay and grain products (experiment 2), was offered in amounts to sustain a moderate gain in body weight, or was reduced step-wise to cause a loss in body weight. Worm egg counts were determined weekly. The reduction in feed on offer resulted in a mean weight loss of 4.0 kg over 9 weeks (experiment 1) or 4.8 kg over 7 weeks (experiment 2). Based on worm egg counts, there was no indication of a change in immunity to T colubriformis in either of the experiments. These results suggest that acquired immunity to T colubriformis in adult sheep that are exposed to infection is maintained during periods of moderate loss of weight associated with inadequate nutrition.
authors.affiliation: CSIRO Division of Animal Health, Pastoral Research Laboratory, Armidale, New South Wales.
authors.forename: M F
authors.initials: MF
authors.lastname: van Houtert
authors.forename: D L
authors.initials: DL
authors.lastname: Watson
authors.forename: I A
authors.initials: IA
authors.lastname: Barger
mesh_terms: D000821:Animal Feed / Q000592:standards; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000909:Antibodies, Helminth / Q000276:immunology; D001835:Body Weight / Q000502:physiology; D004435:Eating / Q000502:physiology; D002523:Edible Grain / Q000592:standards; D005243:Feces / Q000469:parasitology; D007110:Immunity, Active; D008297:Male; D010270:Parasite Egg Count / Q000662:veterinary; D012756:Sheep; D012757:Sheep Diseases / Q000276:immunology* / Q000503:physiopathology; D014253:Trichostrongylosis / Q000276:immunology / Q000503:physiopathology / Q000662:veterinary*; D014254:Trichostrongylus / Q000276:immunology*; D015431:Weight Loss / Q000502:physiology*
chemical_list: D000909:Antibodies, Helminth