BY: TREVOR COOK
The most boring and repetitive job that I do is mow my lawns. No matter how well I do them I know that I will have to do them again in a few weeks. This summer rain makes it more like three weeks. If I do not mow them they become a hay paddock because 50 years ago they became a lawn when a fence was put around a very large house section in a paddock. A hay crop outside the house windows is domestically not acceptable. The regenerative brigade would be proud of my lawn due to its biodiversity arising from its farm paddock origins and its non-selective grazing by my lawn mower. To not have this regular mowing demand I need to do something quite different. Put in synthetic lawn or establish kikuyu would have that effect. Or more drastically, replace the lawn with concrete or asphalt, or create a large shrub garden.
While performing this task this summer I reflected that at a similar frequency on most sheep and beef farms throughout the country lambs, bull calves and dairy heifer calves were being drenched. It is a boring and repetitive job and similarly to my lawn mowing, no matter how well they are drenched, they will need to be drenched again in a few weeks. It is embedded in our farming systems as a necessary animal health task. It will be done monthly at least until the winter, but lots of bull calves and dairy heifer calves are drenched that frequently for 12 months. The consequences of not doing this are likely to be much more severe than those if I did not mow my lawn. Lowered weight gain, dags, and even death are probable outcomes.
After having nearly 60 years of access to effective anthelmintics it is of little surprise that farmers have not come up with a different way to manage parasites in these vulnerable livestock. It is a testament to how effective these products have been since 1964. However there are several reasons why confining internal parasite control to just monthly drenching is plain silly. I admit to frequently advising such as a necessary intervention to prevent significant production costs in the absence of doing something different. Firstly it is silly because to have to treat that frequently means that the stock are being exposed to a consistent and substantial worm challenge. We have science-backed studies that show the liveweight cost to young animals being exposed to such a challenge. Despite frequent drenching, for those same animals to continue to consume a few thousand worm larvae per day will still lower their liveweight gain. That weight gain loss can be up to 45% without there being any sign of a worm burden.
Secondly, there is a significant cost to this approach to managing worms. Product, time and yarding are all costs. For lambs 30 to 40 cents per drench dose, for calves nearer $1-plus. Add to that the time cost which is very often not accounted for in such analyses. But separate to this I believe that there is a significant production cost to yarding. The incidence of enzootic pneumonia for example, could be influenced by the amount of yarding for lambs. If we could better quantify that cost we might be more circumspect about how much we do.
The third reason why this singular approach to managing worms is silly is that after 60 years the worms have been given the opportunity to develop resistance to these once effective products. Drench failure is now so widespread that this embedded repetitive practice is no longer as effective as it once was.
Just as for me to not have to mow my large lawn so often I need to do something quite different with it, to get away from this current worm management practice requires a different approach. Given that we know a lot about the parasitic worms that we are dealing with, in particular their life cycles, that there are grazing techniques out there that depower those cycles and we know how effective forage programmes are in disrupting the cycles, why on the majority of farms is four-weekly drenching still the norm? Particularly when there are good reasons why it is a silly management practice. I get tired of the word sustainable, but in this case the current practice is not sustainable in any way. I no longer get any satisfaction from giving advice on sustainable worm management. After 40 years of trying to do that I now have to accept that I failed. Not just me, but the industry has failed to encourage enough behaviour change for us to not end up with so much drench resistance. But beside this, as described above, there are two other compelling reasons why the current practice of four-weekly drenching is silly. I have heard from many old farmers how prior to getting thiabendazole drench lamb losses were huge and two-tooth weights were poor. But I have also heard from some old farmers how they planned grazing areas for lambs using beef cattle and how effective that was to reduce these losses. The new drenches were so effective that those enlightened grazing systems got swept aside.
I do get satisfaction from helping set up management systems that reduce the need to drench. Lamb and calf weight gains are higher and overall costs are less. This is about looking at whole farm systems, exploiting the strengths of our multi-species and age class stock mixes and the varied landforms. It is not about being organic or regenerative, but borrowing some of their concepts could help. We need to be a lot smarter.
