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https://hdl.handle.net/1959.11/10123
Title: | No loss of production due to larval challenge in sheep given continuous anthelmintic treatment via a controlled release capsule | Contributor(s): | Kelly, Gareth A (author); Walkden-Brown, Steve W (author)![]() ![]() |
Publication Date: | 2012 | DOI: | 10.1016/j.vetpar.2011.07.033 | Handle Link: | https://hdl.handle.net/1959.11/10123 | Abstract: | This study aimed to quantify production loss due to larval challenge in sheep administered a controlled release albendazole capsule (CRC) and thus determine the suitability of CRC treated sheep as a proxy for worm-free sheep in grazing experiments. The experiment used an incomplete 2 x 3 latin square design with 81 Merino wethers. Sheep were either infected (INF) with mixed oral infection of albendazole-susceptible 'Haemonchus contortus', 'Trichostrongylus colubriformis', and 'Teladorsagia circumcincta' (initial bolus then thrice weekly maintenance) or remained uninfected (UINF). Worm control treatments were with a CRC (CRCT), threshold treatment with a short-acting anthelmintic when worm egg count (WEC) exceeded 1500 epg (TT) or untreated (UT). The experiment was conducted in two 63-day periods (separated by a 14 day washout period) with infection treatments swapped between periods. A subset of animals was killed at the end of each period for worm counts and tissue sampling. Faecal worm egg count in UINF-UT reached 10,204 and 6078 epg at day 63 in periods 1 and 2, respectively, and remained 0 throughout in the CRT treatments. There was no difference in live weight gain or wool growth of INF-CRCT sheep (67 and 70 g/d) relative to UINF-CRCT (67 and 76 g/d). Live weight gain was significantly lower in INF-UT (27 g/d) and INF-TT (55 g/d) than UINF-UT (88 g/d) or UINF-TT (81 g/d) treatments. During the first infection period, greasy fleece weight growth was significantly lower in INF-UT (6.33 g/d) and INF-TT (6.37 g/d) than UINF-UT (7.80 g/d) or UINF-TT (7.32 g/d) treatments. The effects of infection on production persisted in INF-UT, but not INF-TT sheep for several weeks after termination of infection. Eosinophil counts were elevated in all infected groups and the antibody response to 'T. colubriformis' was greater in INF-CRCT and INF-TT groups compared to uninfected sheep. Together, these results indicate that larval challenge in sheep with a CRC is mildly immunogenic but is not associated with production loss. The results also showed that the CRC itself reduced live weight gain and that anthelmintic treatment at a WEC threshold of 1500 epg reduces production loss during infections and prevents persistence of adverse effects following infection. | Publication Type: | Journal Article | Source of Publication: | Veterinary Parasitology, 183(3-4), p. 274-283 | Publisher: | Elsevier BV | Place of Publication: | Netherlands | ISSN: | 1873-2550 0304-4017 |
Fields of Research (FoR) 2008: | 070708 Veterinary Parasitology 070205 Animal Protection (Pests and Pathogens) |
Fields of Research (FoR) 2020: | 300909 Veterinary parasitology 300304 Animal protection (incl. pests and pathogens) |
Socio-Economic Objective (SEO) 2008: | 830311 Sheep - Wool 830310 Sheep - Meat |
Socio-Economic Objective (SEO) 2020: | 100413 Sheep for wool 100412 Sheep for meat |
Peer Reviewed: | Yes | HERDC Category Description: | C1 Refereed Article in a Scholarly Journal |
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Appears in Collections: | Journal Article School of Environmental and Rural Science |
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