Initiative that faced drench-resistance head-on

Blair and Jane Smith continue to challenge all Newhaven Stock under nil-drench three decades on from David Ruddenklau’s work.

“This is no time for ease or comfort, it is the time to dare and endure” – wise words from Winston Churchill – and relevant to the drench-resistance battle that our sheep sector faces today.

Otago sheep breeder David Ruddenklau’s decision 30 years ago to breed a sheep that required very little drenching (and eventually no drench) would be a game-changer for the New Zealand sheep sector.

The 1990s were a hard time in the farming sector, especially North Otago – an area that spent most of the decade in debilitating drought.

David’s original goal to decrease the amount and frequency of drenching wasn’t from a cost-saving point of view, but from a “robustness” ethos, frustrated at the industry mindset of blanket drenching every few weeks or months.

In the early 1990s, David ceased all drenching of ewes and then worked with AgResearch to identify genes within Newhaven stud lambs and hoggets that had the genetic resilience to “fight and still grow” under a high worm burden. The “feast or famine” grass growth curve of North Otago meant high worm burdens often overwhelmed sheep during warm, wet periods following a drought.

While faecal egg counting (FEC) was a massive step forward for the industry, David wasn’t particularly interested in seasonal peaks and troughs of worm burden, but instead how each animal responded to the burden of high worm counts. Finding bloodlines that had the innate ability to get on and earn their keep in terms of growth rates while some of their peers needed to be culled out under a nil-drench regime was the key.

Humble beginnings have led to over three decades of nil-drench at Newhaven.

In 1990 worm antibody testing commenced in all hoggets at Newhaven, analysing antibody levels at work to fight both clinical and sub-clinical effects of the challenge, lined up against seasonal conditions, weight and growth rates. Interestingly, the 1990 test-kit handbook pre-warned of “looming drench-resistance throughout New Zealand from reliance on high drench regimes” – a haunting prediction of the position the sector finds itself in today.

Rome wasn’t built in a day and nor was the identification of bloodlines with an inbuilt resilience to worm burden, but as a stud operator, David felt an obligation to march on and continue to identify a way forward.

In 1996 as a trial, a third of all ram lambs were un-drenched from birth to sale. The demand for these ‘nil-drench’ rams conservatively increased over the first few years – initially from organic farmers – but after observing that the nil-drench rams looked just as impressive as their peers, the demand for the nil-drench rams skyrocketed and demand outgrew supply. By 2009 all ram lambs born would remain totally un-drenched from birth to sale, two decades after the original testing was carried out at Newhaven. This remains a pioneering industry initiative today with genetics one of the few tangible tools available to face drench resistance head-on.