Targeted use of bioactive forages as a treatment for lambs

Abstract

A production-based TST was used to identify individual lambs suffering from parasitism and subsequently graze them on bioactive forages (chicory, plantain, white clover) to provide a chemical free method of control. Overall growth rates of lambs grazing either T. circumcincta or T. colubriformis infected blocks were 200g/d and 160g/d respectively. There was a significant paddock time effect (p<0.05) on both blocks reflecting a benefit of hospitalisation on lamb live weight gain (LWG) early in the season, with 80% of lambs responding to switch in sward (treatment). Anthelmintic use improved growth rates by 32% and 39% in comparison to TST animals (P<0.01) for T. circumcincta and T. colubriformis blocks, respectively. Mean FEC were high (>1000epg) on both blocks and there were no significant differences in FEC between animals grazing ryegrass or hospital paddocks. In year two the bioactive effect of the plantain /chicory sward was investigated. Drenching of lambs onto bioactive sward was no more beneficial than drenching back onto pasture however LWG were reduced by 80% in untreated lambs grazing on either ryegrass or plantain /chicory sward which suggests that previous results were a response to reduced larval intake and not due to any bioactive forage effect.