Cattle are raised for profit so any added rearing costs equate to loss. Parasites have a negative effect on the cattle economy as they impact the health and productivity of animals. The strategic use of pasture management and anthelminthic drugs can negate the effect of worms, but they also have an associated cost. Balancing the cattle economy to maximise profit involves finding the economic threshold for when best to treat worms. Thresholds will vary among properties, the types of worm you are treating against, labour costs, the breed, age, gender and accessibility of cattle requiring treatment.
There are multiple published studies investigating the cost benefit of different worm control strategies. For example, using pasture rotation or selective or preventative treatments. These benefits include a reduction in costs (mainly for anthelmintics and treatment-related labour) as well as a benefit in production (particularly milk yield and weight gain). Some examples are provided below:
A recent case study showed that yearling cattle going onto improved pasture treated with an injectable product, 90 days after treatment, weighed on average 10kg more than their untreated herd-mates. The cost of the product was $4/head and mustering and labour costs were $7/head. At the time of the trial, saleyard prices were $3.75/kg liveweight.
Day 0 Treated and untreated group average liveweight = 200kg
Day 90 Untreated group average liveweight = 280kg
Day 90 Treated group average liveweight = 290kg (i.e. 10kg heavier)
Total estimated treatment costs = $4 (product) + $7 (labour) = $11/head
Total estimated benefit from weight gain = 10kg x $3.75 = $37.50
Net benefit of treating cattle = $37.50 - $11 = $26.50/head
In this case, the farmer made $26.50 more per head by treating the animals. The benefit of treating may not always exceed the cost, it is important to realistically estimate the cost of labour and mustering animals.
A one-year long case study compared the cost of using a fixed treatment schedule against only treating animals when deemed necessary (using WECs and decreases in body condition score as decision parameters). The animals at the end of the study showed no differences in average liveweight but there was a dramatic saving in labour and anthelminthic costs by only mustering and treating animals when it was necessary.