Capsules offer parasite control option

Sheep farmers are stepping into another farming year with strong prospects of continuing good returns, and the opportunities to build on flock performance and health are greater than ever.

Richard Sides, veterinary technical advisor with animal health company Boehringer Ingelheim says the start of the new farming year is a good time to re-assess flock parasite management, and getting selective about treatments with flocks can help make the most from already promising returns.

One of the most frequently debated tools available for parasite control is the long acting anthelmintic capsule.

A recent research study on the use of long acting capsules conducted by Massey University associate professor in sheep and cattle production Anne Ridler was released in the New Zealand Veterinary Journal earlier this year.

The research has revealed the success that can accompany selective use of long acting capsules in younger sheep, with positive cost-benefits being delivered.

Professor Ridler’s research studied the production responses of long acting pre-lamb capsule treatment in two flocks of commercially run hoggets. The benefit of the treatment was determined by measuring weight gains made in ewes, and final weaning weights of their lambs.

As a group, ewes one year old or younger are recognised as a stock class that could potentially expect a more consistent benefit from long acting capsule treatment. This is due to their immunity to parasites being less developed than that in older sheep.

Because there was a lack of published studies to prove this, the researchers decided to investigate the production responses from two flocks of hogget ewes.

The results of the research showed that in the flock where an economic analysis was done there was a definite cost:benefit advantage in using the capsules.

The treated ewes in both flocks recorded both a higher lamb weight at weaning, and higher ewe weight at weaning. In the flock where the further measures were done the treated hoggets went on to extend their weight-gain advantage going into the following tupping.

The extra lamb weights were two fold. They came directly in the current season, and in the likely extra lambs coming from the heavier 2-tooth tupping weights leading to higher lambing percentage in the following season.

These were added together where they equated to a gross extra return of $13.29 per ewe.

Allowing for a capsule cost of $3.85, the net return of $9.44 per treated ewe represents a significant economic gain. No economic analysis was carried out for reduced dags, increased fleece weights, or reduced numbers of ewe replacements required over time.

The researchers found the average success to weaning of the ewes in the study was only 65-68%, at the lower end of what most farmers would expect in hogget systems.

They concluded the cost:benefit return from using capsules may actually be underestimated due to the lower performance of the trial flock, compared to the results some farmers achieve with their hogget flocks.

The researchers cautioned the study did not measure the effect of long acting capsules on increased drench resistance, or the long term cost should that develop.

Richard Sides said the capsule research was encouraging news for farmers looking at all the tools in their tool box to manage parasites.

“What the study highlights is that with care and selection there is a place for capsule use.

“As a class of sheep more vulnerable to parasite impact, hoggets are ideal to target in combination with some management practices that should assist in mitigating resistance issues.”

This can include allowing a number of “refugia” animals in the flock, ideally older, more immune animals in with hoggets that don’t get treated with a capsule. This helps maintain a reserve of untreated parasites within the population.

Taking faecal egg counts prior to treatment can also indicate the level of infestation. This allows a rational assessment of the parasite challenge the animals are likely to face, along with the amount of parasite contamination they may contribute to the paddocks over the spring.

“And egg counts done post treatment will also help ensure there has been no egg leakage post-treatment, confirming that the desired effects are achieved.”

Wrapped around good management practices is a consulted worm control programme with the farmer’s veterinarian. This will involve discussing the year’s plans for drenching, taking into account resistance risk, stock combinations and the optimal blend of drench technologies to maximise worm control without compromising with resistance development.

“Smart planning and management means the drench options we have before us can remain sustainable for years ahead, and a targeted approach to drench type and active working alongside your vet can achieve this.”

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