The active ingredients in products used for sheep dipping and the treatment of external parasites, along with footbathing, are integral to operating efficient sheep production systems. If used incorrectly however, these products also pose a significant risk to water ecosystems.
Safeguarding these ecosystems is dependent on ensuring product does not enter water sources. This can occur from a few avenues. The source that automatically comes to mind is spent product being disposed of incorrectly.
However, a risk that is often not accounted for, but which can be significant depending on the circumstances, is spent dip being transferred from sheep directly to water sources. This can occur from freshly dipped sheep passing through water courses, or rain washing fresh dip from the fleece of sheep.
Teagasc staff in Donegal have been active in raising awareness around this topic in recent years. Shaun Roarty, an adviser with the Agricultural Sustainability Support and Advice Programme (ASSAP) has outlined best practice in this area, while Teagasc advisers have taken part in developing a video in conjunction with a number of bodies involved in the CatchmentCare Programme, which will be discussed in detail later.
Looking firstly at Shaun Roarty’s advice, he highlights that the use of sheep dips has gained increased attention in recent years, due primarily to active ingredients such as cypermethrin being suspected in waterways.
Shaun says that when such substances are found in streams and rivers, it can be confidently concluded that aquatic living insects will have been eliminated. This, in turn, has serious consequences for the health of other species (fish, birds, small mammals, humans) that are reliant on aquatic insects as part of the overall food chain.
Shaun’s advice on handling sheep dipping and footbathing products is as follows;
These recommendations also relate to pour-ons, which use active ingredients such as cypermethrin. Pour-ons, when applied to the fleece, should be allowed to dry effectively before sheep go back to an open hill or mountainous area and also any lowland area where watercourses are present.
It is advisable when making up the sheep dipping solution or footbath to wash and rinse the opening caps, foils and containers once empty. This way, the rinse solution can contribute to the solution, which will cut down on the volume of liquid to be disposed of after.
The containers will also be ready to be recycled appropriately. Unwanted concentrate must be disposed of to a licensed specialist waste disposal contractor. Local authorities will provide information on licensed contractors.
Spent sheep dip or footbathing solution should never be disposed of to a soak pit or applied on lands without the appropriate dilution in slurry or water. The advice for spent sheep dip, as outlined by the Department of Agriculture and published by the HPRA, is to dilute at a ratio of 1:3 with slurry or water and to land spread at a rate not exceeding 5,000l/ha (440 gallons per acre) of spent dip, equivalent to 20,000l/ha (1,760 gallons per acre) of diluted dip.
Similar advice is recommended by Shaun for spent footbathing solution. It is vital to note that all precautions pertaining to the spreading of animal manures are also applicable to spent sheep dip and footbathing solution, including prohibited application dates and adherence to buffer zones.
Only apply spent product to lands which have a low water pollution risk.
This means that spent solution should be stored at present until the prohibited period for applying slurry has passed. Livestock should also not graze on these areas for at least one month after spreading has taken place.
A detailed video developed by Teagasc Donegal and the CatchmentCare Programme, in association with the Loughs Agency, Donegal County Council, the Department of Agriculture and Interreg (link up between Northern Ireland, Ireland and Scotland), can be found at https://www.teagasc.ie/news--events/daily/sheep/catchmentcare---teagasc-sheep-dipping-demonstration.php.
In the video, Sean Gallanagh, catchment officer, Loughs Agency explains that the project is focused on exploring the effect that pesticide contamination has on the water quality of the Finn river in Donegal.
From a sheep dipping perspective, Sean says there are two main pesticides of concern – cypermethrin (non-organophosphate) and organophosphate compounds.
While the two chemicals differ in their make-up, they have a similar effect on aquatic insects.
“Generally, they disrupt the nervous systems of the insects, causing paralysis which leads to starvation after a while. The pests that are present on sheep (external parasites) are in the same macroinvertebrate family as those present in the river, so the pesticide basically has the exact same impact on both of them. That has to be taken in to account – if the pesticide gets in to the river, it will kill the local macroinvertebrate population just as readily as it will kill the pests on the sheep.”
If this happens, it will have grave consequences on the ecosystem within this river, as Sean outlines that the macroinvertebrates provide ecological functions such as shredding leaves and organic matter, make bacteria for fish by consuming it and making it available up the food chain. If these die off, it will remove the feed source for fish, which in turn will have a knock-on effect up the food chain.
In outlining best practice techniques, Morgan Lane, Bimeda Animal Health, says the starting point in dipping must be to have clean facilities and clean water. An accurate measurement of the dipping tub is essential for establishing how much chemical to add and top-up rates.
When mixing the dip, no other chemicals such as fleece colourants should be added to the mixture, as these, he says, can have a detrimental effect on the quality of the dip. Sheep should be allowed to rest for a couple of hours and enter the bath without adding contaminants resulting from excessive fleece daggings or soiled hooves/feet.
The head of the sheep should be fully immersed at least twice during dipping, along with ensuring the body of the sheep is well soaked.
It is crucial for sheep to spend at least 60 seconds in the dipping bath to prevent sheep scab.
“Allow 60 seconds for the dipping. That’s a full minute. It’s a long time to be standing over [sheep] so there is plenty of time to duck down the head of sheep. Sheep need that time to allow the wash to get in to the skin where the parasites are.”
Morgan points out that sheep remove a considerable amount of dip when exiting the bath and sufficient time must be allowed in the draining pen to allow this to flow back to the dipping bath.
Sheep should not be released from the draining area until they have visibly stopped dripping. Morgan says that sheep should not be shorn for three months post-dipping and that protective clothing and gloves should be worn.
The bath should be replenished after every 36 sheep and the recommended volume of concentrate should be added to ensure the solution is maintained at the correct strength.
“The sheep strip active ingredient out of the solution, it clings to their wool and weakens the batch, so it is crucially important that replenishment or topping up is carried out correctly,” Morgan says.
“One sheep per 2l of the capacity of the bath, the bath must be emptied and refilled. What that means is that for a 1,000l bath, the maximum number of sheep that should be put through is 500 sheep.”
Solution must not be retained in the bath overnight for dipping on the following day under any circumstances, as there is a huge risk of post-dipping lameness in dirty baths or baths held overnight without emptying and starting afresh. Morgan also points out that sheep should not be treated with any levamisole-based products for 14 days before or 14 days after dipping, as there is a risk of toxicity.
There are tight restrictions in place in Northern Ireland surrounding sheep dipping. Sheep producers in NI or contractors supplying dip must possess a Certificate of Competence in the Safe Use of Sheep Dips in order to purchase sheep dip. Farmers who dip sheep and spread spent dip on their land also have to receive authorisation from the Northern Ireland Environment Agency (NIEA). The regulations were covered in detail previously on the sheep pages and can be sourced in this article on www.farmersjournal.ie.