Threshold levels of artificial infection with Haemonchus contortus impacting lamb physiology and production
Year: 2025
Type: article
Abstract: This study examined the effects of levels of artificial Haemonchus contortus infection on lamb behaviour and physiology. Forty 6-month-old Romney-cross wethers were assigned to one of four treatments (n = 10/treatment): 8000 L3 larvae (High; H), 4000 L3 larvae (Medium; M), 1000 L3 larvae (Low; L), or water (Control; C). Lambs were monitored 1 week pre- and 6 weeks post-treatment. Weekly measurements included faecal egg counts, liveweight, blood counts, and cytokine concentrations (e.g., IL-6). Behaviour was continuously monitored using cameras and accelerometers. Faecal egg counts increased in H, M, and L lambs from week 3 post-treatment, exceeding 830 epg in H and M lambs by week 6 (P ≤ 0.05). No behavioural differences were observed (P > 0.19). At week 3, H lambs had lower red blood cells, haemoglobin, and haematocrit, and higher mean corpuscular volume (P < 0.02). IL-6 concentrations tended to be higher in H lambs from weeks 4–6 (P = 0.06). Liveweight gains were lower in challenged lambs by trial end, differing significantly from controls 2 weeks post-trial (P = 0.04). These results suggest that while H. contortus infection may not affect lamb behaviour, higher doses (4000–8000 larvae) cause dose-dependent physiological changes indicative of anaemia, immune activation, and reduced weight-gain, negatively impacting lamb welfare and productivity.
Source: Figshare
Authors: Hempstead, Melissa, Candy, Paul, Hannaford, Rina, Ross, Mallory, Sutherland, Ian, Sauermann, Christian
Institution: AgResearch
Language: English
Subfield: Small Animals
Field: Veterinary
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7077488787
FWCI:
Cites:
Cited by:
Related to: