Chickens can start eating crushed eggshells as a calcium supplement around 8 weeks old, aiding in healthy bone and eggshell development.
Feeding eggshells to chickens is a time-tested practice that provides essential calcium for strong egg production. But timing matters – give them too early, and you risk health issues. Here’s everything you need to know about when and how to safely feed eggshells to your flock.
Why Chickens Need Eggshells
Eggshells are 95% calcium carbonate – the same material found in commercial oyster shell supplements. When hens lay eggs, they lose significant calcium reserves. Without proper replenishment, you’ll notice:
- Thin or missing eggshells
- Increased egg eating behavior
- Bone weakness in older hens
According to poultry researchers, a single egg contains about 2 grams of calcium – nearly 10% of a hen’s daily requirement. Recycling shells closes this nutritional loop.
The Calcium Cycle in Layers
Here’s how calcium moves through your flock:
| Stage | Calcium Need | Source |
|---|---|---|
| Pullets (0-18 weeks) | Low | Starter feed only |
| Point-of-Lay (18-22 weeks) | Increasing | Layer feed + optional supplements |
| Peak Production (22+ weeks) | High | Layer feed + calcium supplements |
When to Introduce Eggshells
The critical rule: Wait until your entire flock is laying consistently (typically 18-22 weeks). Early introduction risks:
- Premature egg production in pullets
- Kidney damage from excess calcium
- Egg binding in underdeveloped hens
For mixed-age flocks, separate feeding stations help. Mature hens can access eggshells while keeping them from younger birds. Introducing new birds requires similar careful management.
Signs Your Hens Need Calcium
Watch for these indicators:
- Soft-shelled or shell-less eggs
- Increased broken eggs in nesting boxes
- Hens pecking at freshly laid eggs
How to Prepare Eggshells
Proper preparation prevents egg-eating habits and ensures safety:
Step-by-Step Processing
- Collect shells in a container (rinse if dirty)
- Dry at 200°F for 15-30 minutes (optional but recommended)
- Crush to pea-sized pieces (not powder)
- Store in airtight container until use
Pro tip: Bake shells to eliminate salmonella risk. A USDA study shows 200°F kills pathogens while preserving calcium.
Feeding Methods
Offer shells:
- In a separate dish from feed
- Mixed with oyster shell (50/50 ratio)
- Scattered in run to encourage natural foraging
Never mix directly into feed – hens overdose risk. Free-choice access lets them self-regulate intake. For flocks with egg-pecking issues, provide shells in private areas to prevent bad habits.
Quantity Guidelines
Average consumption:
- 1 tsp crushed shells per hen every 2-3 days
- Adjust based on egg production rates
- Reduce in winter when laying decreases
Special Situations
Mixed Flocks
For coops with roosters or non-layers:
- Use separate feeding stations
- Choose darker-colored containers (roosters avoid)
- Monitor for overconsumption
Alternative Calcium Sources
When shells aren’t available:
- Oyster shell (most commercial option)
- Limestone grit (digestive aid + calcium)
- Calcium-rich greens (kale, spinach)
Remember: Eggshells should supplement – not replace – a balanced layer feed. Proper nutrition ensures your hens stay productive and healthy through their laying years.