Blowfly strike

There have been many more reports of blowfly strike in the last week, with some cases increasing in severity. Part of the increased incidence is likely due to sheep sheltering during peak daytime temperatures and more fly activity in the shade.

As such, it is important to monitor sheep regularly. As touched upon in the recent sheep handling focus, the manner in which blowfly preventative product is applied will have an influence on the level of protection achieved.

Product should be applied to a clean fleece and in a manner that promotes optimum binding to the fleece. This includes avoiding periods of peak temperatures where there is a risk of product evaporating before optimally binding with the fleece.

It is easy to overlook safety concerns when applying pour-ons to treat and prevent external parasites. However, there is a significant risk of inhaling chemicals through aerosol mist of liquid particles. As such a respiratory mask with appropriate chemical filters should be used, along with correct protective clothing to prevent absorption through the skin.

Nematodirus

There are also some reports of lambs displaying clinical signs of nematodirus – i.e. a characteristic green-coloured scour, a sharp drop in performance and in serious cases, lambs congregating around water troughs.

It is important to note that some flock owners may have to treat lambs more than once, as there is no product that offers residual cover.

Lambs currently at risk are those born later in the season that have received no treatment to date or that may not have been aged between six and 12 weeks of age and consuming significant volumes of grass when the first treatment was administered. The product of choice remains a white drench, or the benzimidazoles class of anthelmintic to lower the risk of resistance developing to other worm species.

SIS egg counts

This week’s summer animal health focus discusses worm control and the importance of ensuring anthelmintics are working effectively.

For flocks participating in the parasite control (faecal egg count) action of the Sheep Improvement Scheme (SIS), it is important to note that faecal egg counts must be submitted to a laboratory approved for the scheme by the Department of Agriculture. A full listing can be found on the SIS page of the Department’s website.

To recap on actions, lowland flocks must submit a minimum of two faecal egg counts between 1 June and 30 September 2025. The second count must be taken at least seven days after the first. The aim of the action is to establish the worm burden to make informed decisions in relation to a dosing regime. Hill flock participants must carry out one faecal egg count on lambs for the presence of worms within four weeks post-weaning within the scheme year.

Weed control

Forecast rainfall will boost grass growth but also growth in weeds. The optimum treatment stage for most weeds in grassland swards is the rosette stage, or when plants are at a height of about 150mm to 250mm or 6in to 10in for docks, nettles, etc.

The growth pattern of thistles is different and allows optimum spray coverage at a height of 200mm (8 inches). It is important to follow manufacturer’s guidelines regarding the safe use of pesticides to protect water quality.