Pre-housing wormer can control lungworm-initiated pneumonia and promote extra growth

Worming suckler beef calves or dairy heifers up to five weeks before housing with a pour-on moxidectin treatment can reduce lungworm and associated pneumonia in the early housing period, and produce enough extra live-weight gain off autumn grass to cover treatment costs more than seven-fold [Ref 1], according to Zoetis vet Andrew Montgomery.

“Typically, pasture lungworm burdens peak in late autumn,” he says. “Recent warm weather with intermittent rain has also been conducive to a build-up of gastrointestinal worm infectivity on pasture.”

By getting cattle worm-free for five weeks pre-housing, SAC beef adviser Dr Basil Lowman estimates that growth rates could be boosted by up to 0.15kg per head per day.[Ref 2] Over that period, cattle could therefore gain an additional 5.25kg in body weight (35 days x 0.15kg/day = 5.25kg), which at today’s values is worth about £10.76.[Ref 1]

This strategy is effective, according to Mr Montgomery, because moxidectin offers persistency against re-infection by stomach worms (Ostertagia) and lungworm (Dictyocaulus) of five and six weeks respectively from a single dose.

“Bearing in mind that many farmers with cattle at grass will use a wormer at housing as a matter of course, this strategy does not require them to make an additional treatment, just a switch in timing,” he says. “Also, with the dose being related to bodyweight, earlier treatment means the quantity of wormer used, and therefore cost per head, is lower.”

According to Dr Lowman, the most compelling reason for following this plan is reduced pneumonia risk at housing. “Pneumonia is the biggest cause of financial loss, not to mention a major welfare problem, in cattle rearing,” he says. “If it causes just one fatality, then many more animals on the same unit will also be affected, will never recover fully, and will lose money.

“Treatment for lungworm ahead of housing allows time for dead worms to be coughed up and for lung damage to repair while cattle are still outside and under low stress,” Dr Lowman continues. “This gives the best chance for their lungs to be recovered and as ready as possible for the stresses of housing when the time comes.”

Moreover, he warns that, while animals may look physically fit at this time of the year, a surprising proportion can be carrying some lungworm burden. “It really is worth making the effort to treat them before housing,” he urges. With pneumonia prevention in mind, Dr Lowman recommends a four-step protocol: Pre-housing treatment with persistent-action wormer. Pneumonia vaccine given pre-housing. Clipping animals’ backs, one clipper width either side of the backbone from neck to tail-head. Well drained, well ventilated, draught-free housing.

For farms where pre-housing wormer is not practicable, Andrew Montgomery suggests the next best thing is moxidectin pour on at housing. A winter-long lice-free guarantee is also offered to farmers using this treatment (trade name, CYDECTIN® Pour On for Cattle) by manufacturer Zoetis. For advice specific to their own units about applying the Control of Worms Sustainably (COWS) recommendations [Ref 3] and terms of the lice-free guarantee, farmers should consult their veterinary surgeon or an SQP at their animal medicine supplier.

1 Agricultural merchant website accessed 30 August 2013 ( £195.00 for 5.0 litres = 4p/ml. Dose for 350kg animal = 35ml @ 4p = £1.40/animal (cost rounded up), for a >7.7:1 return at £10.76/head increase in value (Farmers Guardian, 23 August 2013, average lightweight steer price £2.05/kg liveweight).

2 Dr Basil Lowman, 3 August 2011. Interview with the author.

3 Prof MA Taylor, 2010. Control of Worms Sustainably. Co-published by EBLEX and Dairyco (divisions of the Agriculture and Horticulture Development Board).