Parasite resistance in sheep - sheepgenomics program trials

The sheepgenomics program sought to discover the differences between sheep bred to be resistant to parasitic gastro-intestinal nematodes (GIN), and those bred to be susceptible to infections with these parasites.\nThe data provided details the design of sheep trial experiments and data from the animals housed in the experiments, including information identifying individuals and their relatedness. The experiments were approved to be conducted under the animal ethics legislation of NSW, with animal research authorities (ARAs) issued by the CSIRO Armidale animal ethics committee (ARAs 03/75, 04/49, 05/58).\nLineage: Sheep in these trials were raised to be helminth naive (HN). HN lambs are born either indoors or transferred indoors during the first day post parturition. The indoor environment has either wooden slatted or steel mesh flooring so that faeces from sheep is separated from the animals. The environment is maintained so that no plant growth can occur. These provisions prevent parasites infecting sheep via the faecal-oral route, so that HN lambs had no immunological exposure to parasites prior to their use in the trials. Lambs were kept indoors with their dams until weaning at approximately 12 weeks of age when the dams were returned to the outdoor environment. \nSheep were between 99 and 139 days of age when they were entered into the trials. The trials were:\nFG1 - conducted 2003/4\nFG2 - conducted 2004/5\nFG3 - conducted 2005/6\nTrichostrongylus colubriformis infections occurred in FG1, with euthanasia at day 3 of either a primary or a third infection.\nHaemonchus contortus infections occurred in FG2, with euthanasia at day 3 of either a primary or a third infection.\nBoth H. contortus and T. colubriformis infections were conducted in FG3, with euthanasia after 3, 7, 14 or 21 days of a primary infection.\nIn FG1 and FG2 unrelated, uninfected HN animals were kept in the experiment alongside the others. In FG3 related uninfected HN animals were kept in the experiment alongside the others.\nThe sheep were from either the Haemonchus selection flock (HSF aka AB49) or the Trichostrongylus selection flock (TSF). Both flocks had been subject to genetic selection over more than 30 years prior to the experimental trials and consisted of two lines; a resistant line (R) bred for increased resistance to parasite infection, and a susceptible line (S) bred for decreased resistance to parasite infection. The selection protocols for the TSF and HSF flocks differed somewhat and further information can be found in the publications listed in the explanatory notes.