Eggshell Strength & Lay Rate Feed-Additive Zeolite for Layers

Q: Does adding zeolite to layer feed improve eggshell strength?

Natural clinoptilolite is not itself a calcium source, so it is not a direct calcium supplement for the eggshell. However, numerous feeding trials such as Macháček et al. (2010) and the works they cite, Roland et al. (1985) and Nys (1999), reported that zeolite with high cation-exchange characteristics can form a complex with dietary calcium and slightly improve eggshell quality, with effects more apparent when dietary Ca is marginal (about 2.75%) or during heat stress. In other words, the eggshell benefit should be understood as a supporting effect mediated by improved calcium utilization and gut-tract environment, not as a replacement for the calcium source.

Q: What inclusion rate is appropriate, and is more always better?

No. Macháček et al. (2010) reported that adding 2% clinoptilolite to layer feed raised mean egg weight to 64.69 g, significantly higher than the control (63.73 g), while daily feed intake fell to 114 g; at 4%, however, egg weight dropped to 62.20 g, feed intake rose to 124 g, and some blood parameters such as hemoglobin were negatively affected. Therefore, 2% or less is presented as optimal for layers, and the FDA GRAS anti-caking limit is also 2% or less of the total formulation.

Q: Does it help reduce cracked eggs and soft-shell losses?

Cracked and soft-shell losses arise from multiple factors, including eggshell strength, late-lay bird age, calcium metabolism, and heat stress. Zeolite can slightly improve eggshell quality and support feed utilization and the gut-tract environment, but it is not a pharmacological means that guarantees a lower cracked-egg rate on its own. Treat it as a supporting material used alongside calcium-source (limestone, oyster shell) particle-size management, increased late-lay calcium, and husbandry and ventilation management; before adoption, a pilot feeding trial that applies a small dose to one flock and compares cracked-egg rate and shell thickness against a control is recommended.

Q: Can the same product be used for poultry-house ammonia and litter management?

Yes. Use 100-mesh powder for feed addition, and 14×40 mesh granules for spreading on the house floor and litter. Nakaue et al. (1981) and Karamanlis et al. (2008) reported supporting effects of clinoptilolite in poultry on house environment and ammonia generation. Studies have also reported reducing ammonia generated from layer manure with zeolite, so the feed-grade and litter-grade products can be operated separately by particle size.

Q: Are certification documents available?

KMIZEOLITE holds numerous certifications including OMRI Listed (KMI-10365), FDA GRAS (animal feed intake use, 21 CFR 582.2729), TSCA compliance, and EN-71-3 PASS, and has received approval for use in the EU swine and poultry industries. See the certifications page.

The challenge on layer farms: rising cracked-egg rate, weakening soft and hard shells, and declining late-lay performance

On layer farms, the losses that translate directly into revenue mostly arise from eggshell quality. First, as the flock moves into late lay, the shell thins and the rate of cracked eggs and soft-shell eggs rises, increasing grading and shipment losses. Second, during summer heat-stress periods, feed intake falls and calcium metabolism is disrupted, further lowering eggshell strength. Third, the mycotoxin (aflatoxin, etc.) load of ingredients such as corn worsens lay rate, egg quality, and liver health together.

Unlike general growth support for broilers, this field must be reviewed from the perspective of calcium-metabolism and gut-tract-environment improvement, centered on the layer-specific economic indicators of eggshell strength, cracked-egg rate, and lay rate. In addition, because feed additives are regulated, the inclusion rate and use limits must be confirmed first.

Why zeolite is considered in layer feed

Natural clinoptilolite is a mineral with micropores of 4.0–7.0 Å and a cation-exchange capacity (CEC) of 1.6–2.0 meq/g. The important point is that zeolite itself is not a calcium source. Eggshell calcium must come solely from calcium sources such as limestone and oyster shell; zeolite is reported to contribute indirectly and supportively to eggshell quality through a buffering action that temporarily captures and then passes ammonium (NH₄⁺) and some cations within the gut tract, and through complex formation with calcium via high cation-exchange characteristics.

The evidence from layer-specific feeding trials is central. Macháček et al. (2010) fed ZeoFeed (clinoptilolite ≥80%) at 2% and 4% levels for 28 days to Bovans Goldline layers and reported that the 2% group's mean egg weight rose to 64.69 g, significantly (P≤0.01) higher than the control (63.73 g), daily feed intake fell to 114 g (control 118 g), and the metabolic utilization of nitrogen (33.69→35.87%), fat, nitrogen-free extract, starch, and total energy improved together. By contrast, the 4% group's egg weight instead dropped to 62.20 g, feed intake rose to 124 g, and some blood parameters such as hemoglobin were negatively affected, leading them to conclude that 2% or less is optimal in layer feed (Macháček et al., Acta Veterinaria Brno, 2010).

Regarding eggshell quality, this study summarizes that zeolite with high cation-exchange characteristics can form a complex with dietary calcium and slightly improve eggshell quality (Nys, 1999; Roland et al., 1985), with the effect more pronounced when dietary calcium is at a marginal level (about 2.75%) or during heat. In addition, the review by Papaioannou et al. (2005) synthesizes that clinoptilolite has been reported to provide supporting effects on feed efficiency and intestinal health in poultry, swine, and ruminants (Papaioannou et al., Microporous and Mesoporous Materials, 2005). On the mycotoxin side, Rizzi et al. (2003) co-fed aflatoxin B1 and clinoptilolite in layer feed and evaluated egg quality, hepatic toxin residues, and liver enzyme activity (Rizzi et al., Journal of Food Protection, 2003).

KMIZEOLITE's natural clinoptilolite is 97% pure, mined and processed at the Amargosa Valley mine in Nevada, USA, with a specific surface area of 40.0 m²/g, a stable pH range of 3.0–10.0 (covering the pH variation of the chicken gut tract), and thermal stability to 700°C (accommodating pellet-processing temperatures), making it suitable for layer-feed blending processes. The FDA recognizes it as GRAS for anti-caking use under 21 CFR 582.2729 (animal feed intake use), and the European Union has approved its use in the swine and poultry industries.

KMIZEOLITE key properties

Item	Value
Clinoptilolite purity	97%
Cation-exchange capacity (CEC)	1.6–2.0 meq/g
Specific surface area	40.0 m²/g
Pore diameter	4.0–7.0 Å
Stable pH range	3.0–10.0
Hardness	4.0–5.0 Mohs
Thermal stability	700°C
Specific gravity	1.89
Bulk density	45–54 lbs/ft³
Certifications	OMRI KMI-10365, FDA GRAS, TSCA, EN-71-3

Layer application examples: eggshell- and lay-performance-centered scenarios

Below are representative application scenarios in which zeolite is considered on layer farms. All feed addition is reviewed at 2% or less of the total formulation under the FDA GRAS standard, for eggshell/gut-tract support and anti-caking purposes, and does not replace the calcium source.

Peak- and late-lay eggshell-support blend: mixing 100-mesh powder at 2% or less into layer compound feed to support calcium utilization and gut-tract buffering (Macháček et al., 2010; 2% optimal basis). The calcium source (limestone, oyster shell) is maintained separately and sufficiently
Heat-period lay-performance management: in summer periods of reduced feed intake and disrupted calcium metabolism, considering 2%-or-less addition to support eggshell strength (the eggshell effect is more observed during heat and at marginal calcium)
Response to mycotoxin load: when using toxin-risk ingredients such as corn, blending it in together as an adsorption aid to distribute the load (cf. Rizzi et al., 2003). Run alongside separate toxin testing and management
House litter and bedding spreading: spreading 14×40 mesh granules on the house floor and manure surface to adsorb ammonia and moisture, improving the footpad and respiratory environment (cf. Nakaue et al., 1981; Karamanlis et al., 2008)
Pilot feeding trial: applying 2% or less to one flock and comparing cracked-egg rate, shell thickness, eggshell strength, lay rate, and egg weight against a control before deciding on full adoption

Recommended particle size and product specifications

In the layer-feed field, Powder (100 mesh) is suitable for compound-feed mixing, and Medium Granule (14×40 mesh) is suitable for house litter and bedding spreading. Because smaller particles are advantageous for uniform dispersion in mash feed, the powder form is considered first for feed mixing. Refer to the table below to select the product group that matches your use.

Product group	Mesh	Particle size	Typical use
Powder	100 mesh or finer	<150μm	Pozzolan, feed, powder adsorption
Fine Granule	30×50 mesh	0.3–0.6mm	Water treatment, filtration, soil
Medium Granule	14×40 mesh	0.4–1.4mm	Filter media, litter, bedding
Coarse Granule	8×14 mesh	1.4–2.4mm	Swimming pools, de-icing, large filtration
Extra Coarse	4×8 mesh	2.4–4.8mm	Packed beds, air scrubbers

→ View products by mesh size · Product selection guide by use

Layer feeding-trial and field review points

When applying zeolite to layer feed, the following items must be confirmed together.

2%-or-less optimum and limit: Macháček et al. (2010) reported increased egg weight and reduced feed intake at 2%, and decreased egg weight and worsened blood parameters at 4%. The FDA GRAS (21 CFR 582.2729) anti-caking limit is also 2% or less of the total formulation, so no pharmacological effect beyond this range is claimed
Maintain the calcium source separately: because zeolite is not a calcium source, keep the calcium source (limestone, oyster shell) and its particle size (proportion of coarse particles) as is, and position zeolite only as support for calcium utilization and the gut-tract environment
Measure eggshell indicators: record eggshell strength, shell thickness, cracked-egg rate, soft-shell rate, lay rate, and egg weight together with a control to quantitatively evaluate the effect (cf. the Macháček, 2010 method)
Distinguish heat and late lay: because the eggshell-support effect is more observed when dietary calcium is marginal or during heat, clarify the application timing (late lay, summer)
Ingredient toxin load: confirm the blending ratio of mycotoxin-risk ingredients such as corn and the toxin-testing history (cf. Rizzi et al., 2003)
Certification check: to use it as an organic-livestock feed ingredient, confirm OMRI Listed (KMI-10365) compliance. The EU has approved its use in the swine and poultry industries

→ View TDS (product data sheet) · View MSDS (safety data sheet)

Layer feed FAQ

Does adding zeolite to layer feed improve eggshell strength?

Natural clinoptilolite is not itself a calcium source, so it is not a direct calcium supplement for the eggshell. However, numerous feeding trials such as Macháček et al. (2010) and the works they cite, Roland et al. (1985) and Nys (1999), reported that zeolite with high cation-exchange characteristics can form a complex with dietary calcium and slightly improve eggshell quality, with effects more apparent when dietary Ca is marginal (about 2.75%) or during heat. In other words, the eggshell benefit is best understood as a supporting effect mediated by improved calcium utilization and gut-tract environment, not as a replacement for the calcium source.

What inclusion rate is appropriate, and is more always better?

No. Macháček et al. (2010) reported that adding 2% clinoptilolite to layer feed raised mean egg weight to 64.69 g, significantly higher than the control (63.73 g), while daily feed intake fell to 114 g; at 4%, however, egg weight dropped to 62.20 g, feed intake rose to 124 g, and some blood parameters such as hemoglobin were negatively affected. Therefore, 2% or less is presented as optimal for layers, and the FDA GRAS anti-caking limit is also 2% or less of the total formulation.

Does it help reduce cracked eggs and soft-shell losses?

Cracked and soft-shell losses arise from multiple factors, including eggshell strength, late-lay bird age, calcium metabolism, and heat stress. Zeolite can slightly improve eggshell quality and support feed utilization and the gut-tract environment, but it is not a pharmacological means that guarantees a lower cracked-egg rate on its own. Treat it as a supporting material used alongside calcium-source (limestone, oyster shell) particle-size management, increased late-lay calcium, and husbandry and ventilation management; before adoption, a pilot feeding trial that applies a small dose to one flock and compares cracked-egg rate and shell thickness against a control is recommended.

Can it also be used for the effect of mycotoxins (aflatoxin) on laying performance and egg quality?

Rizzi et al. (2003) co-fed aflatoxin B1 and clinoptilolite in layer feed and evaluated the effects on egg quality, hepatic toxin residues, and liver enzyme activity. Clinoptilolite has been studied as an adsorption aid for some mycotoxins in feed, but the binding effect varies with toxin type, concentration, and raw-material condition; therefore, when using toxin-risk ingredients such as corn, it is advisable to run separate toxin testing and management alongside it and to verify the effect through a small-scale trial.

Can the same product be used for poultry-house ammonia and litter management?

Yes. Use 100-mesh powder for feed addition, and 14×40 mesh granules for spreading on the house floor and litter. Nakaue et al. (1981) and Karamanlis et al. (2008) reported supporting effects of clinoptilolite in poultry on house environment and ammonia generation. Studies have also reported reducing ammonia generated from layer manure with zeolite, so the feed-grade and litter-grade products can be operated separately by particle size. See the product selection guide by use.

Are certification documents available?

KMIZEOLITE holds numerous certifications including OMRI Listed (KMI-10365), FDA GRAS (animal feed intake use, 21 CFR 582.2729), TSCA compliance, and EN-71-3 PASS, and has received approval for use in the EU swine and poultry industries. Check the certifications page.

Inquiries and sample requests

If you are considering applying zeolite to support layer eggshell and lay performance, please get in touch through the channels below.

Notice

Whether the application is suitable may vary depending on field conditions, regulations, and test results. Before actual application, a test review tailored to the field conditions must always be conducted first. Zeolite is not a cure-all for the eggshell and lay field, but is best understood as a material that supports the calcium source and husbandry management.