Farmer-led mineral focus group in face of drench resistance

Drench resistance has been a ticking time bomb for a while. Veterinarian Erin Riley first saw the signs of it in the UK before she moved to New Zealand, but was hopeful that the evolution of combination drenches would buy more time.

Resistance was seen as a more of a North Island problem, but it became apparent that rapid acceleration of drench resistance was affecting her North Canterbury farming clients after years of drought, and that the dry had been masking a much bigger problem right under her nose.

“We are looking for it now, but I suspect we have had an issue for a while. When it was dry there wasn’t much drenching either, but the 2022 and 2023 wet season meant there were a lot more parasites about,” she explains. 

North Canterbury Veterinary clinic has been working with local farmers combining regular faecal egg testing for parasites alongside knowledge of their drench use and farming systems.

In reviewing the data to find trends across dry and wet seasons, Erin says there is still huge variability from farm-to-farm. With the reduction in drench use, she fears farmers are unaware of the levels of trace minerals that are in some drenches, and are still required. For instance, with the removal of the bionic capsules that had 100 days of cobalt and selenium, the animal still requires a source of these key minerals in replacement in the face of parasite pressure in the pasture.

“We are only starting to scratch the surface as most of the research was done in the 80s and 90s and we farm so differently now. We also have different sheep genetics, so what they knew back then may no longer be relevant. It will take a lot of onfarm testing and a real focus on mineral solutions for the next 10-15 years to combat the situation we are in as a country.”

Why not apply the required minerals to the soil?

“Depending on the trace elements, as some can transition between the soil to the animal, you have to test the soil to know it’s there. It then has to be available to the plant to uptake and then eaten by the animal and then the animal has to utilise the minerals. Not all minerals operate that way,” explains Erin. 

An example is copper. A herbage test would indicate the plant has taken up the copper from the soil from fertiliser, but when it enters the sheep there are other trace elements, such as molybdenum (moly), sulphur and iron that affect the absorption of copper and the animal is therefore still deficient.

Selenium does transfer from the soil to the animal, but needs to be put on at the right time for when the animals need to absorb it, as it doesn’t last in the soil for 12 months.

Cobalt is crucial for turning into B12 in sheep but she says grass doesn’t always actively take up the cobalt, so if it’s not growing at all from the dry, or growing fast, high-soil cobalt levels don’t transition to animal availability.

How do you select the right products?

Erin works with Vetpak Healthy Ewe product range and Smartrace Sheep Boluses, which have been an integral part in her mineral toolbox of solutions for her farmer clients.

“You have your general oral drenches that have most goodies in them if you just want something you can drench and feel good. But if you want to target what you are deficient in, then you can target what the animal needs at certain times in the season,” she explains. Sheep have high physiological demands for certain vitamins and minerals during critical periods of their reproductive cycle, pre-tup and late pregnancy, which may not be met by their normal feed intake. Vitamin E, for example, has been shown in trials to be a key trace element with lamb survivability.

Vetak offer a strategic range of short acting oral multivitamin / mineral supplements under the Healthy Ewe range designed to provide supplementary levels of trace elements during these critical periods.

If you are in a hill country farm system where yarding-up ewes and lambs every few weeks is labour intensive, considering Smartrace Sheep boluses could be an advantage.

‘What we are finding is even neighbours have different challenges and solutions that work. There is no one size fits all.’ – Erin Riley, North Canterbury Veterinary Clinic

Boluses ensure you are setting up your lambs for success with iodine, selenium and cobalt when ewes are in lamb and will provide active cover for four months.

“Everything comes down to the right fit for the right system. For some, the cost of boluses may not make sense compared to an oral supplement, especially if you are on the flat and yarding is relatively straightforward. But if you are on hill country and mustering every few weeks is harder, you will want the length of action and the ease of administration of a bolus. You just have to weigh up the cost versus the labour and what’s right for your system.”

Bolus application with a contractor on a conveyor may help ensure they are correctly administered if you and your team are not confident to do it yourselves.

Farmers learning from farmers

Erin’s dedicated mineral focus group with North Canterbury sheep farmers has provided a peer-learning environment for the past four years.

They take data from lamb liver biopsy and blood tests pre-mating, pre-lamb time to see what the trends are in trace elements and they have a discussion three times a year about different products and approaches. The next step is to overlay production data and see what impact it’s having. 

“I present the data and they talk it over amongst themselves about different angles to try. I don’t mind what they want to try, I just want to track it as it might be useful for someone else to try. What we are finding is even neighbours have different challenges and solutions. There is no one size fits all,” shares Erin.

For example, she says with some of the long-acting mineral injections, if they reduce the dose rate it won’t last as long, but it will last the length of time required to be effective which cuts the cost back but gets the full benefit.