A new feed batch arrived a week ago. The birds eat reluctantly, laying has slid five points in a few days, the shells are worse, and a couple of hens have diarrhea. No disease, no heat, no drafts. The vet asks to see a bag — and finds gray-green clumps at the bottom. This is what mycotoxin poisoning usually looks like: quiet, no obvious illness, across the whole flock at once.
What mycotoxins are
They are toxic compounds produced by molds. The fungi grow on grain in the field or in damp storage, and the toxins stay in the grain even after the mold is gone: neither drying nor pelleting destroys them. So clean-looking grain can be dangerous, and moldy grain almost certainly is.
| Toxin | Most often in | What it does to birds |
|---|---|---|
| Aflatoxins | Corn, peanut meal, cottonseed cake in warm, humid conditions | Damage the liver, weaken immunity so vaccines work worse; pale birds and yolks |
| Ochratoxin | Grain stored damp | Kidneys: birds drink a lot, wet droppings, laying drops |
| T-2 and related toxins | Grain left in the field over winter, damp storage | Sores and crusts in the mouth and on the beak, feed refusal |
| Deoxynivalenol (vomitoxin) | Wheat and corn after a wet summer | Birds eat less; poultry tolerate it better than pigs, but harm grows when combined with other toxins |
Signs in the flock
- birds eat the new batch worse, scratch it out and pick through it;
- laying falls for no visible reason, shells get thinner;
- pale combs and yolks although the formula hasn’t changed;
- birds drink more, droppings are loose;
- crusts and sores at the corners of the beak and in the mouth;
- vaccines work worse, young birds get sick more often, broilers grow slower.
If problems started a few days after a new feed batch or new grain, and neighbors on different feed are fine, check the feed first.
How to check feed
- Eyes and nose. Clumps, gray, green or pinkish patches, a musty smell, a bag that feels warm — set the batch aside.
- Grain moisture. For storage, grain should be no wetter than 13–14%. Above that, mold is almost inevitable.
- Rapid test. Test strips for aflatoxins and other toxins are sold for farms and grain elevators. They’re cheap compared to flock losses.
- Lab. If you already suspect poisoning from the birds, send a sample of the same batch for analysis. Keep half a kilo of each batch in a sealed bag until it’s used up — without that sample you can’t argue with the supplier.
Storage: where feed goes bad
- Condensation in the bin. A metal bin in the sun heats up by day and cools at night, dew forms on the walls, and feed along the walls cakes and molds. Empty and clean the bin completely between batches.
- Bags on the floor and against the wall. Pallets only, 20–30 cm from the wall.
- Old under new. Don’t pour a new batch on top of the old one: feed what arrived first, first.
- Feeders. Feed wetted by drinkers or rain can mold in a feeder within a day. Wet feed goes in the trash.
- Rodents. They tear bags, let moisture in and spread disease themselves.
If you already suspect it
- Stop feeding that batch immediately and replace it.
- Take a feed sample and, if birds have died, send one for necropsy.
- Give a course of vitamins in the water — the liver and immune system are under strain.
- Ask your vet about mycotoxin binders: they bind aflatoxins fairly well and other toxins less so, and they’re no excuse to feed known bad feed.
- Note the start and end dates of the batch: later they show what the bad feed cost you.
Laying usually recovers within one or two weeks after the feed is replaced, if the exposure wasn’t long. Young birds that got toxins in their first weeks may never catch up with their peers.
Feed batches in your records
In EggPulse every feed delivery goes into the store with a date and supplier, and the egg and feeding logs sit right next to it. When laying drops, you can see whether it lined up with a new delivery. How to run the feed store so feed doesn’t sit too long is in the feed inventory article.
