Move Interval, Parasites and the Pastured-Poultry Myths

#"Broilers were never observed foraging in pats"

That sentence is in the results of the only controlled trial of the model everyone sells you: chickens run behind cattle to break the fly and parasite cycle. The researchers put broilers onto pasture behind an organic dairy herd, at two densities, and measured face fly larval survival in the dung pats.

Survival was 4.4% in pasture with no broilers, 5.6% at low broiler density, and 3.2% at high density — against 54.4% in a bird-free greenhouse control (Phillips, Moon, Sorge & Heins 2020, Animals 10(12):2429).

Look at where the effect lives. The overall treatment effect is statistically strong (χ²(3) = 55.2, p < 0.01) — and it is driven entirely by the greenhouse control. The three pasture treatments are indistinguishable from one another, and that is the comparison the claim depends on. The pats were being cleared by the arthropods that live in and hunt in dung. Not by the chickens, which the observers never once saw foraging in a pat.

#The move rule, and what sets it

For a mobile broiler pen, the rule is blunt: move at least daily, and the pen should never come to rest on ground it has already dunged. In peak Highveld summer — hot, humid, thunderstorms, the highest coccidiosis risk of the year — move twice a day if you can.

For day-range and net-and-hut systems, the trigger is different. Move before the living vegetation inside the netting drops below 50% cover. That is not a preference.

The regenerative control for coccidiosis is not a drug. It is a move interval and a rest period — the same recovery logic you already apply to grazing. Where the specifics of any remedy are concerned, the product, its use and any withdrawal period come from the registered label under the Fertilizers, Farm Feeds, Agricultural Remedies and Stock Remedies Act 36 of 1947 and from your veterinarian or Animal Health Technician. This course gives you the decision rule and stops there.

#Myth one: the eggmobile breaks the parasite cycle

In the only controlled test, broilers on pasture did not reduce face fly larval survival in dung pats. Now read that study's context before you apply it. It ran at the West Central Research and Outreach Center in Morris, Minnesota, on an organic dairy, with broilers following cows. That makes it more relevant to the eggmobile-behind-cattle model, not less — it is the exact system, tested. But it is one study, in one country, and it has never been replicated in South Africa.

So keep the eggmobile — and change the sales pitch. Following cattle with layers genuinely spreads nutrients, genuinely produces weekly cash on a farm whose cattle pay out every eighteen months, and genuinely puts a second enterprise onto the same hectares. Say that. Drop the parasite claim. It is the most repeated ecological claim in pastured poultry and it does not survive contact with the one study that tested it.

#Myth two: guinea fowl control ticks

The second claim fails in a more interesting way.

In the only controlled trial, the single significant difference was between free-range and fully excluded treatments (t = −4.03, P = 0.016) — and there was no significant difference between penned birds and exclusion. Penned-versus-excluded is the comparison that would demonstrate actual tick consumption rather than mere disturbance of the plot, and it came out flat. Worse for the claim, the researchers recovered engorged tick nymphs from the coop floor whose blood meals were confirmed to have come from the guinea fowl themselves. The authors concluded there is "no evidence that guinea fowl are an effective biological control" (White, Cumbie, Brinkerhoff, Hynes & Gaff 2024, J. Med. Entomol. 61(2):410–417).

Guinea fowl are tick hosts as much as tick predators. That is the finding, and it is the one nobody selling guinea fowl mentions.

Now read the transferability caveat before you teach this as settled for South Africa, because it matters. The trial ran in Virginia, in the United States, against the lone star tick (Amblyomma americanum). South Africa's economically important ticks are different species with different questing behaviour and different host relationships — Amblyomma hebraeum, the vector of heartwater; Rhipicephalus species including the blue ticks; Hyalomma species. No South African study of guinea fowl, or of any poultry, as tick biocontrol could be found.

So the honest statement is: "guinea fowl are not a tick control strategy" is the best reading of the best available evidence, and it is an inference across continents and tick species rather than a South African finding. Say the conclusion and the caveat in the same breath. Then keep guinea fowl for what they demonstrably are on a South African smallholding — loud, alert, semi-feral alarm birds that tell you something is in the camp.

#The honest case, at full strength

There is one more reason to hold that line, and it cuts against the enthusiasm rather than with it. A pastured poultry enterprise imports fertility rather than generating it. Ask the question directly: your 500 broilers ate roughly 1.7 tonnes of maize and soya — where did the phosphorus in that grain come from, and where is it now? It is on your paddocks, in a distributed pattern, which is genuinely useful. It is also imported from cropland elsewhere, and on a small holding used repeatedly it becomes nutrient loading rather than fertility building.

The closest South African-relevant evidence on concentrated manure deposition is the kraal literature, and it should be read carefully rather than triumphantly. Kraals and bomas roughly double soil concentrations of carbon, nitrogen, phosphorus and potassium relative to adjacent soil — but that comes from a meta-analysis of only twelve studies across several biomes and countries, with inconsistency scores of I² at or above 90%, and the authors' own conclusion that while the average effect was positive, in some cases the true outcome may in fact be negative (Momberg et al. 2023, African Journal of Range & Forage Science 40(1)). Their further warning transfers directly: in mesic grassland, concentrated deposition is promising for rehabilitating degraded ground or abandoned cropland, and should be avoided where the grass sward is still intact. That is cattle kraaling, not poultry — the authors were not writing about birds, and the analogy is this course's rather than theirs. The caution is still the right one to carry onto a Highveld range.

So track the number that tells you which side of the line you are on: kilograms of imported feed nutrient per hectare per year. Spread wide, it is fertility distribution. Concentrated on the same two camps, it is fertility dumping with better optics.

#What to do on Monday

Mark a fixed transect line across your range and walk it with a step-point count this week, so that "50% living cover" becomes a number in a notebook rather than an impression. Then go through your own marketing — your website, your market-stall patter, your WhatsApp group — and delete every sentence claiming that your birds control parasites, break fly cycles or eat ticks. Replace them with the three claims you can defend in front of anyone: weekly cash flow, nutrient distribution across the farm, and a customer who knows your name.