Please use this identifier to cite or link to this item: 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)orcid ; Kahn, Lewis  (author)orcid 
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: Amsterdam, The Netherlands
ISSN: 1873-2550
0304-4017
Field of Research (FOR): 070708 Veterinary Parasitology
070205 Animal Protection (Pests and Pathogens)
Socio-Economic Outcome Codes: 830311 Sheep - Wool
830310 Sheep - Meat
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
Statistics to Oct 2018: Visitors: 248
Views: 263
Downloads: 0
Appears in Collections:Journal Article
School of Environmental and Rural Science

Files in This Item:
2 files
File Description SizeFormat 
Show full item record

SCOPUSTM   
Citations

7
checked on Nov 26, 2018

Page view(s)

62
checked on Mar 1, 2019
Google Media

Google ScholarTM

Check

Altmetric


Items in Research UNE are protected by copyright, with all rights reserved, unless otherwise indicated.