Case Study-Noonameena

Brian Cusack and his son Andrew run a mixed farming operation on undulating fertile country south-east of Young (Annual rainfall about 650mm). They run a fine wool Merino self-replacing sheep flock, a small Hereford beef cattle herd and grow winter crops. Noonameena is a conservatively managed property with good improved pastures and excellent nutrition of livestock.

In 1986 Dr John Evers, District Veterinarian with the Young Rural Lands Protection Board, chose Noonameena as a profile property to begin intensive monitoring. Dr Evers set up a number of profile properties and the results were used as an extension tool throughout the district.

Prior to 1986 Brian had used the drench he found most convenient – which was levamisole. Brian had noted scouring in his flock and testing confirmed high level resistance to levamisole (53% efficacy LEV, 100% BZ). Brian switched to a white drench, which had not been used on the property for 10–15 years. Within two seasons, significant resistance to the white drench re-emerged. By 1989 there was significant dual resistance to white and clear drenches.

“At this point we decided to move away from the conventional system of only using drenches with 95% efficacy because that was going to lock us into ML and my belief was that within five years we could be looking at ML resistance,” explains Dr Evers. “We opted to use drenches of about 80% efficacy in rotation with an ML. We were able to use white/clear combination drenches for this but their efficacy deteriorated rapidly.”

In 1996 Rametin was launched and was immediately incorporated into the drench program at Noonameena. “We’ve been using the Rametin/BZ combination in annual drench rotations for eight years with excellent results across the district, said Dr Evers.

“For example, last summer we used the Rametin/BZ combination at Noonameena and it gave close to 100% activity with no need to further drench the breeding flock for 12 months. That’s how effective it was.”

Dr Evers believes the introduction of Rametin has allowed Noonameena to delay the onset of ML resistance by giving them a rotation option rather than using MLs every drench. “My belief is that if we hadn’t had access to Rametin I’d be telling you today that we had mectin resistance.”