Parasite Control in Southern Prime Lamb Production Systems

Summary

Awareness that internal parasites were a threat to profitability of an expanding prime lamb industry prompted establishment of a project to study their epidemiology and economic impact and improve efficiency of worm management programs. Research was conducted on fifteen properties in South Australia and Victoria.
The most important worms are Trichostrongylus and Ostertagia. Peak transmission is from May –
September, but can continue through summer in coastal areas. Seasonal patterns are similar on irrigation and dryland. Problems include autumn contamination of paddocks, failure to provide clean weaning paddocks, quality decline of irrigated pasture in summer and variable efficacy of drenches.
The main losses were due to reduced growth rates. In 38% of trials, worms reduced growth by
12.2%, with daily penalties averaging 19 g/day. Estimated annual impact on the lamb industry in South Australia, Victoria and the Riverina is $65.73 million, comprised of $49.47 million (74%) direct losses and $16.26 million (26%) in control programs.
Comprehensive new knowledge is provided on prime lamb worm management in all production systems, suitable for uptake by a wide range of producers. Modest changes on properties with significant worm problems can realise huge savings for the industry.