Chickens eat gravel to aid digestion, as it helps grind up food in their gizzards, ensuring they can effectively process their grain-based diet.
If you’ve ever watched chickens pecking at the ground, you may have noticed them swallowing small stones and gravel. This behavior isn’t accidental – it’s a vital part of their digestive process. Unlike humans, chickens lack teeth to chew their food, so they’ve evolved a fascinating system using gravel as natural “teeth” inside their bodies.
The Chicken Digestive System Explained
Chickens have a unique digestive system that works in reverse compared to mammals. Here’s how it works:
- Food enters the crop (a storage pouch)
- Moves to the proventriculus (stomach) for enzyme breakdown
- Passes to the gizzard where gravel grinds it
- Nutrients are absorbed in the intestines
The Gizzard: Nature’s Food Processor
The gizzard is a muscular organ containing the gravel chickens swallow. As the gizzard contracts, the stones pulverize food into digestible particles. This process is so effective that chickens can digest whole grains and tough plant matter that would pass undigested through other animals.
Types of Grit Chickens Need
Not all grit is created equal. Chickens require different types at various life stages:
| Age | Grit Size | Description |
|---|---|---|
| Chicks (0-8 weeks) | #1 Grit | Fine as sand |
| Pullets (8-20 weeks) | #2 Grit | Small gravel pieces |
| Adult Chickens | #3 Grit | Pea-sized stones |
What Happens Without Enough Grit?
Chickens without access to proper grit can develop serious health issues:
- Sour crop: Food ferments in the digestive tract
- Impacted crop: Blockage from undigested food
- Nutrient deficiency: Poor absorption of vitamins/minerals
According to Wrong Direction Farm, turkeys can consume up to half a pound of grit weekly as adults. Chickens need proportionally less but still require constant access.
Grit vs. Oyster Shell: Know the Difference
Many chicken owners confuse grit with oyster shell. While both are important, they serve different purposes:
- Grit: Granite or quartz stones for grinding food
- Oyster shell: Calcium source for egg production
As explained in My Pet Chicken’s guide, oyster shell dissolves and doesn’t provide the grinding action chickens need for digestion.
Providing Grit for Your Flock
Even free-range chickens may need supplemental grit. Here’s how to provide it:
- Offer grit free-choice in a separate container
- Scatter in run areas where chickens forage
- Mix with feed occasionally
- Ensure constant access to fresh grit
For chickens in confined spaces, grit is especially crucial. As noted in our article on chicken run size, limited space reduces natural foraging opportunities.
Choosing the Right Grit
Commercial chicken grit is typically:
- Granite or quartz-based
- Insoluble in digestive acids
- Sharp-edged for better grinding
Avoid using sand or dirt as these don’t provide proper grinding action. For young chicks, starter grit should be available as soon as they begin eating solid food.
Natural Grit Sources
In natural environments, chickens obtain grit from:
- Small pebbles
- Crushed stone
- Coarse sand
- Shell fragments
However, as we discuss in our guide to keeping chickens out of gardens, modern yards often lack these natural grit sources.
Signs Your Chickens Need More Grit
Watch for these indicators of grit deficiency:
- Undigested food in droppings
- Decreased appetite
- Weight loss
- Lethargy
- Pasty vent (in chicks)
Healthy chickens with adequate grit will have well-formed droppings and maintain good body condition. Their natural instinct to seek out grit when needed is strong, but confined birds depend on your provision.