Supplementation of ewes on pasture to provide an epidemiological benefit for gastrointestinal parasitism

Abstract

The potential epidemiological benefit of reducing the peri-parturient relaxation in immunity to gastro-intestinal nematode parasites through supplementing twin-bearing ewes during the first four weeks of lactation was evaluated in a replicated farmlet study. In two sequential years, ewes either grazed pasture alone or grazed pasture while supplemented with 0.5 kgDM/d of a high-protein pellet. Supplementation did not affect ewe live weight or body condition score or weight of lamb weaned per ewe (P>0.05). Ewe faecal egg counts (FEC) showed a time x supplementation interaction (P<0.05), being reduced by 50% from week six of lactation in both years, although this only resulted in transient and inconsistent reductions in pasture larval contamination. After weaning, there was no consistent parasitological benefit to lambs grazing areas where ewes had been supplemented that were reflected in either pasture larvae concentrations, lamb FEC, the requirement for anthelmintic treatment or lamb growth rate (P>0.05 for all). Despite supplementation of ewes during the first four weeks of lactation successfully reducing ewe faecal egg count by 50%, this was not sufficient to provide a measureable and consistent epidemiological benefit to the lambs.