Quick Answer: Sour crop is a yeast (Candida) overgrowth in a chicken’s crop, almost always triggered when food sits too long and starts to ferment — from long grass, moldy feed, or an impaction blocking normal emptying. The tell is a crop that’s still squishy or fluid-filled by morning instead of flat, often paired with a sour, yeasty smell on the bird’s breath. Home treatment is withholding food for 12-24 hours, gentle crop massage, and sometimes diluted apple cider vinegar in the water; if the crop still hasn’t emptied after 24-48 hours, it needs a vet and antifungal medication rather than more home care.
A chicken’s crop is supposed to work like a delivery queue: full after eating, empty again by the next morning before the bird eats again. Sour crop is what happens when that queue backs up and the contents start to ferment instead of moving through — and because the early signs (a slightly full-feeling crop, a bird that’s a bit quieter than usual) look almost identical to nothing being wrong at all, it’s easy to miss for a day or two. This guide covers how to tell sour crop apart from a normal full crop, how to treat it at home, and what actually prevents it from coming back.
Sour crop vs. a normal full crop vs. impacted crop
| Sign | Normal (post-meal) | Impacted | Sour crop |
|---|---|---|---|
| Feel | Full, firm | Hard, doughy, doesn't move | Squishy, fluid-filled, gurgly |
| Empties overnight? | Yes, flat by morning | No | No |
| Smell | None | Usually none | Sour, yeasty odor |
| Bird's behavior | Normal | May look normal early on | Often quiet, off feed, lethargic |
| Action | None needed | Fluids + massage, vet if it persists | Withhold food + massage, vet if no improvement in 24-48h |
By the numbers
- Sour crop is a Candida (yeast) overgrowth, not a bacterial infection — which is why antibiotics don’t fix it and can make things worse by killing off the competing bacteria that normally keep yeast in check.
- The standard home protocol is withholding solid food for 12-24 hours while keeping water available, giving the crop a chance to empty on its own before escalating treatment.
- Keepers who use apple cider vinegar in the water typically dose it at 1 tablespoon per gallon — it’s thought to help maintain the crop’s pH against candida growth, though Southland Organics and other poultry-health sources note that rigorous studies on ACV specifically in chickens are limited, so treat it as a helpful adjunct rather than a cure on its own.
1. Confirm it’s actually sour crop
Feel the crop first thing in the morning, before feeding
- Check before the flock's first feed of the day, since a crop right after eating is supposed to be full — the useful signal is whether it's empty by the next morning.
- Squishy or fluid-filled with a sour smell points to sour crop; hard and unmoving points to impaction; either way, food sitting in the crop overnight is the shared red flag.
- A digital kitchen scale kept near the coop makes it easy to track whether an affected bird is losing weight day to day while you treat it.
Getting your hands on the crop daily during the first week of any coop change — a new treat, freshly mown grass in the run, a feed switch — catches a slow-emptying crop before it has time to sour. Sign up for Amazon Prime free for 30 days and next-day delivery means a crop-massage guide, a probiotic, or a chick-safe waterer replacement lands before a mild case has a chance to turn into an emergency.
2. Withhold food and massage the crop
| Do | Don't |
|---|---|
| Withhold solid food 12-24 hours, keep water available | Keep feeding normally while the crop is backed up |
| Massage gently, working from the bottom of the crop upward | Press hard or squeeze — the crop tissue is delicate |
| Isolate the bird so it can't grab treats or long grass | Return it to free-range with the flock mid-treatment |
| Recheck the crop each morning before feeding again | Assume one massage session solved it |
Isolating the affected bird matters as much as the massage itself — a chicken back out with the flock will keep pecking at grass and treats, which is exactly what got the crop backed up in the first place. Several short massage sessions spread through the day, working upward from the base of the crop toward the throat, do more than one long session and are gentler on the tissue.
3. Support recovery with diluted apple cider vinegar
Plain apple cider vinegar (with the "mother")
- Unpasteurized ACV is thought to help the crop maintain a pH that discourages further candida growth while it recovers — use it alongside withholding food and massage, not as a standalone fix.
- Only use plastic or non-reactive waterers with vinegar in the water; it corrodes some metal fittings over time.
- Stop ACV once the bird is back to normal feeding and a probiotic is a better long-term choice for rebuilding healthy gut bacteria.
Once the crop is emptying normally again and the bird is back on regular feed, a poultry probiotic for a few days helps rebuild the beneficial bacteria that keep yeast populations in check — this is the step that most reduces the odds of a repeat episode, since a bird that’s had sour crop once is more prone to it recurring.
4. Know when it’s beyond home treatment
If the crop still hasn’t started emptying after 24-48 hours of withholding food, gentle massage, and diluted ACV, or the bird is lethargic, not drinking, or visibly losing weight, home care has reached its limit. Advanced cases need the crop manually expressed and antifungal medication from a vet — tipping a bird upside down to drain the crop yourself is a technique some experienced keepers use, but it carries a real risk of aspiration if done wrong, so it isn’t something to improvise without guidance the first time.
5. Prevent it from coming back
Keep long grass, string, and moldy feed out of reach
- Mow or fence off patches of long, fibrous grass in the run — it's one of the most common causes of the crop impaction that leads to sour crop.
- Store feed in a dry, sealed container so it never molds or ferments; our chicken feed storage container guide covers airtight options.
- Remove string, twine, and stringy garden waste from the run, and keep waterers clean — dirty water gives yeast an easier foothold, and our chicken waterer guide covers easy-to-clean designs.
The bottom line
Check crops each morning before the first feed — flat and empty is normal, squishy or fluid-filled with a sour smell is not. Catch it early and home treatment is straightforward: withhold solid food for 12-24 hours, massage gently a few times a day, and consider diluted apple cider vinegar in the water as support. If the crop hasn’t started emptying within 24-48 hours or the bird looks unwell, that’s the line where a vet and antifungal medication take over from home care. Long-term, keeping long grass mowed, feed dry, and waterers clean prevents the large majority of cases from starting at all.