Visiting one of the many public platforms such as Facebook will quickly convince you that there is a great deal of ignorance surrounding parasite control in small stock. Questions as to which dosing agent is best is met with free, usually uninformed, advice ranging from the use of Epsom salt, diatoms and effective micro-organisms, to overdosing animals using various active ingredients.
Fact is that dosing agents are expensive and it is therefore essential to base answers on facts, rather than conjecture. Unfortunately, an element of guesswork will always be present as worms have built up resistance over the years, mainly due to the indiscriminate use of anthelmintics. The most effective remedy is not a brand name or specific active ingredient, but the one that destroys all worms with a single dose.
Utilising the Famacha method
The Famacha method is very effective in identifying worm carriers, but only applies to blood-sucking wireworms. It indicates anaemia, which is linked to worm load, in animals. Producers can then decide whether to dose or not. However, a dosing agent’s effectiveness cannot be determined by using the Famacha method, as it takes several weeks before the red blood cell counts (by which anaemia is identified) return to normal after dosing.
Faecal egg counts
Faecal egg counts are not an alternative to Famacha; instead, it supports effective worm control. Research shows that, in an average small-stock flock, 70% of the worms occur in 30% of the animals. Infested animals can be identified using the Famacha method, but the dosing agent’s effectiveness can only be proven through a faecal egg count.
Faecal egg counts provide four important facts about the flock. Firstly, it proves that worms are present. Dosing with costly deworming agents is therefore unnecessary if animals have no worms. Secondly, it indicates worm load – only animals with high worm loads need to be dosed.
Thirdly, it allows for a flock profile relating to the occurrence of worms in individual animals to be compiled and, lastly, it shows how effective an anthelmintic is, or whether there is any resistance to it.
Performing a faecal egg count
Faecal egg counts are straightforward and involves collecting animal faeces, which is packed in an airtight container, kept cool and transported to the veterinarian or laboratory.
Because of the long distances to such facilities or the cost involved in having the manure tested, some producers cannot make use of this method. However, producers can perform their own counts and then discuss the information with the veterinarian.
Doing your own worm egg counts require a once-off purchase of equipment such as a microscope, McMaster slides, and a kitchen processor. The process involves extracting eight to ten pellets of manure directly from the rectum. The samples are placed in plastic bags, individually marked, and stored in a cooler.
When processing the manure 4g of pellets are ground into 30mℓ saturated saline solution. The mixture is then dripped into a McMaster slide and set aside for five minutes, after which the eggs are counted under a microscope.
Interpreting the results
The results are calculated according to a formula and expressed as the number of eggs per gram of manure. These results denote the worm load, according to which informed decisions can be made.
Based on Famacha and the animal’s condition score, for example, the decision may be to dose only animals with more than 3 000 eggs per gram of faeces. Animals with a red Famacha score, a condition score of 3, and a worm egg count of 2 000 eggs per gram will therefore not be dosed.
You will not be able to distinguish between different worm species using the count, but it is possible to distinguish between certain species based on their morphology. Tapeworm eggs, especially Moniezia or the milk tapeworm, are easy to identify through faecal egg counts.
The moving larva inside the egg of the white bankrupt worm makes identification very easy. Brown stomach worm eggs are smaller than those of wireworm, bankrupt worm, and nodule worm. Long-necked bankrupt worm eggs are much larger than those of any other species, and whipworm has a very distinctive brown egg with two blisters on the opposite ends.
Benefits of faecal egg counts
DIY worm egg counts are highly beneficial. Results are available within a few hours of sampling. There is no need to transport samples, saving time and money. Apart from the once-off purchase of equipment, the producer does not have to incur any additional costs.
The University of the Free State offers one-day courses to groups of ten people per course, during which key aspects of faecal egg counts are explained. Due to wide interest and limited space, plans are underway to present the course monthly during summer.
– Leon Kruger, Department of Animal, Wildlife and Grassland Sciences, University of the Free State
For enquiries, send an email to Leon Kruger at KrugerL3@ufs.ac.za.