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Richard Paratte, Ph.D. — Global Ruminant Technical & Innovation Manager, Vetagro S.p.A.

Bioavailability is not a fixed property of a product; it is the measured outcome of a release-and-absorption process, captured within a defined analytical window, for a product with a specific intestinal kinetic profile. Comparisons between rumen-protected amino acid products are routinely reduced to a single figure — a bioavailability percentage obtained with one method, on one reference, in one sampling window — as if that number were an intrinsic property of the product, like its methionine content. It is not: the number depends as much on the method as on the product, affecting how technologies are ranked and how decisions are justified on farm. The discussion centers on methionine.

What Each Method Actually Measures

The methods fall into two groups. The first group measures a signal that depends on the timing of amino acid appearance in blood, not only on the total amount absorbed. In vitro and in situ methods estimate ruminal bypass and intestinal digestibility within a fixed incubation window (6 vs. 8 h changes the estimate) and do not measure absorption. The plasma free amino acid (FAA) dose-response method (Whitehouse et al., 2017, 2024) compares the plasma response slope of the test product to a reference (either free methionine infused into the abomasum, and therefore fully absorbed, or a commercial product with an assumed bioavailability), sampling at 2–8 h post-feeding; it was built and validated on fast-release polymeric products. The AUC method (Graulet et al., 2005) integrates the plasma concentration-time curve within the sampling window, so lag and window length set the result. The second group integrates over days rather than hours. The selenomethionine (Se-Met) method (Weiss and St-Pierre, 2009) uses Se-yeast selenium as a methionine tracer: more absorbed methionine dilutes the tracer and lowers milk Se per unit of milk N. Sampling is a multi-day steady-state composite, so the method integrates over time rather than reading a peak; its estimates are relative to an assumed bioavailability for the reference product. Stable isotope dilution (Estes et al., 2018) infuses a labeled amino acid and estimates the fraction reaching plasma, corrected for splanchnic first-pass extraction; it is the most direct approach. Only the first group is sensitive to release kinetics by design. Each method answers a different biological question, so divergent results are not necessarily errors. But when a peak-based method ranks products, part of that ranking reflects how fast each product releases methionine, not how much methionine it delivers in total.

Figure 1. Main methods for evaluating bioavailability of rumen-protected amino acids: what each measures and its main limitation.

Polymeric Coating vs. Lipid Matrix

Products are not built the same way; structure determines release kinetics. Polymeric or pH-sensitive coatings remain stable at ruminal pH and release the amino acid in the acidic abomasum, producing a sharp, concentrated plasma peak (Graulet et al., 2005; Kihal et al., 2021) — the profile the plasma FAA method targets. Microencapsulated lipid-matrix products, such as Timet® (Vetagro S.p.A.), are designed to release amino acid progressively as the lipid matrix is digested in the small intestine; this would produce a lower, longer-duration plasma signal even when total absorption is comparable or greater. A third paradigm — HMBi methionine analogs — is absorbed largely through the rumen wall, by passive diffusion or monocarboxylate transport, peaking at 1.4 h (Kihal et al., 2021).

Figure 2. Schematic plasma methionine kinetics: fast-release, polymeric-coated products (rapid, sharp peak) vs. lipid-matrix products such as Timet® (slow, distributed release that short-window methods are not built to capture).

Why the Sampling Window Matters

A slow-release product cannot generate a plasma peak comparable to a fast-release one: amino acids are cleared from plasma in proportion to their concentration (Estes et al., 2018), so the concentration at any moment tracks the rate of absorption at that moment. Distributed absorption never reaches a high enough instantaneous concentration to register within a short window. Whitehouse et al. (2024) showed that, for a fast-release product, estimates were consistent across 2–8 h, 10–16 h, 18–24 h and 2–24 h windows; lipid-matrix products have been evaluated only within the standard 2–8 h window (Whitehouse et al., 2020), never with an extended one. Graulet et al. (2005) documented a 10-hour lag even for a pH-sensitive product; a short window cannot capture a slower, distributed release.

When Methods Diverge, the Final Word Is Biological

Two Latin-square studies show how loosely analytical ranking maps onto production response. Whitehouse et al. (2020) fed four rumen-protected methionine products at 24 g/d methionine; relative to the polymeric reference product, the other three were estimated at 9%, 24% and 35% effectiveness in supplying metabolizable methionine; Timet® (Vetagro) was the product estimated at 24%. Milk yield and dry matter intake did not differ, although 7-day periods are too short to test production responses. Parales-Giron et al. (2022) compared four products at 15 g/d metabolizable methionine using the Se-Met method; estimates again diverged sharply. DMI, milk yield, and fat did not differ (P > 0.10). Timet® (Vetagro), a lipid-matrix product, showed lower milk protein content and milk N (P < 0.05) than two of the three polymeric products, with the third statistically intermediate, plus a trend toward lower protein yield (P = 0.08); that lower N mechanically inflates the Se/N ratio the bioavailability estimate is built on, even though milk Se itself did not differ among treatments (P = 0.40). Timet® was assigned 37.4% bioavailability there — a relative figure that rests on an assumed 80% for the reference product and on a pre-trial rather than concurrent reference Se/N. Evaluated instead using the same stable isotope dilution technique (Estes et al., 2018), internal trial data on Timet® show 71.78% plasma methionine appearance and 76.80% bioavailability after correcting for 7% splanchnic extraction — consistent with production data showing gains in milk, protein yield (~50 g/d) and ECM (King et al., 2021), and parallel gains in milk protein and fat, with a numerical but non-significant reduction in milk urea nitrogen (P = 0.43; Sáinz de la Maza et al., 2019). Isotopic estimate and production data point the same way.

Figure 3. Timet® (Vetagro), a commercially available lipid-matrix product: plasma FAA dose-response (Whitehouse et al., 2020: 24% relative to the polymeric reference product) vs. stable isotope dilution (internal trial data: 76.80%).

Practical Implications

Three practical conclusions follow. First, a bioavailability figure is meaningless without its method, sampling window, and reference product. Second, peak-based methods (plasma FAA dose-response, AUC) are valid within a release profile (fast, polymeric) but not across structurally different technologies, where they rank release kinetics rather than total amino acid supply; steady-state and isotope methods are less sensitive to release kinetics, but their relative estimates depend on the bioavailability assumed for the reference product. Third, when technologies diverge, the best comparison integrates digestive potential (in vitro/in situ), systemic appearance (plasma/isotopic tracers), and functional outcomes (protein yield, nitrogen efficiency). Economically, cost per gram of metabolizable methionine is only as valid as the bioavailability estimate behind it; a ranking from a mismatched method should not underpin it. When methods disagree, functional outcomes remain the most reliable arbiter.

References

Estes, K. A., et al. 2018. J. Dairy Sci. 101:7040–7060.

Graulet, B., et al. 2005. J. Dairy Sci. 88:3640–3649.

Kihal, A., et al. 2021. JDS Communications 2:182–185.

King, L., et al. 2021. Animals 11(12):3545.

Parales-Giron, J., et al. 2022. J. Dairy Sci. 105 (Suppl. 1):Abstr. 2146M.

Sáinz de la Maza, V., et al. 2019. J. Dairy Sci. 102 (Suppl. 1):350 (Abstr. W85).

Weiss, W. P., and N. R. St-Pierre. 2009. J. Dairy Sci. 92:2835–2842.

Whitehouse, N. L., et al. 2017. J. Dairy Sci. 100:9585–9601.

Whitehouse, N. L., et al. 2020. J. Dairy Sci. 103 (Suppl. 1):122 (Abstr. 315).

Whitehouse, N. L., et al. 2024. JDS Communications 5:539–542.

Timet® is a registered trademark of Vetagro S.p.A. All other trademarks are the property of their respective owners.

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Abstract

Mycotoxins continue to represent one of the most significant biological hazards in global food and feed supply chains. Climate variability, changing agricultural practices, and increasingly complex international trade networks have heightened the risk of mycotoxin contamination in cereals, oilseeds, nuts, and other agricultural commodities. As the 2026 harvest season approaches, proactive testing strategies are essential to ensure compliance with regulatory limits, protect animal and human health, and minimize economic losses. This article reviews the expected mycotoxin risks for the 2026 harvest and presents practical testing strategies for producers, processors, traders, and feed manufacturers.

Introduction

Mycotoxins are toxic secondary metabolites produced by fungi, primarily species belonging to the genera Aspergillus, Fusarium, and Penicillium. These compounds can contaminate crops in the field, during harvest, transport, and storage. The most economically significant mycotoxins include aflatoxins, deoxynivalenol (DON), zearalenone (ZEN), fumonisins (FUM), ochratoxin A (OTA), T-2 toxin, and HT-2 toxin.

The global impact of mycotoxin contamination is substantial. Beyond direct yield losses, contamination can lead to rejected shipments, reduced animal performance, food recalls, and significant reputational damage. Regulatory authorities worldwide continue to tighten monitoring requirements, increasing the need for robust testing programs throughout the supply chain.

Mycotoxin Risk Outlook for the 2026 Harvest

Impact of Climatic Conditions

Climate conditions observed during the 2025/2026 growing season suggest elevated mycotoxin risks in several agricultural regions. Increased frequency of:

• Heat stress periods
• Heavy rainfall events
• Extended humidity during flowering
• Delayed harvest conditions

can create favorable environments for fungal growth and toxin production.

Key Mycotoxins of Concern

Aflatoxins

Aflatoxins remain the most toxic and tightly regulated mycotoxins globally. Produced primarily by Aspergillus flavus and Aspergillus parasiticus, aflatoxins are increasingly detected in maize, peanuts, tree nuts, spices, and other commodities grown under warm and drought-stressed conditions.

Particular attention should be paid to:

• Southern and Eastern Europe
• Mediterranean regions
• North Africa
• Areas experiencing prolonged drought followed by rainfall

Fusarium Mycotoxins

Fusarium toxins remain a significant concern in wheat, barley, oats, and maize.

Key compounds include:

• Deoxynivalenol (DON)
• Zearalenone (ZEN)
• Fumonisins (FUM)
• T-2 and HT-2 toxins

Wet weather during flowering and grain filling stages significantly increases infection risk and subsequent toxin production.

Emerging and Masked Mycotoxins

Growing evidence indicates that masked mycotoxins and emerging metabolites may contribute to overall toxicological burden. Although regulatory frameworks are still evolving, analytical laboratories increasingly include these compounds in comprehensive surveillance programs.

Why Testing Is Essential

Food and Feed Safety

Mycotoxins are associated with numerous adverse health effects including:

• Hepatotoxicity
• Nephrotoxicity
• Immunosuppression
• Reproductive disorders
• Carcinogenicity

Aflatoxin B1 is classified as a Group 1 human carcinogen by the International Agency for Research on Cancer (IARC).

Regulatory Compliance

The European Union, United States, China, and many other jurisdictions maintain strict maximum levels for key mycotoxins. Non-compliant lots may result in:

• Shipment rejection
• Import restrictions
• Product recalls
• Financial penalties

Economic Protection

Early detection enables segregation of contaminated lots before they enter processing streams, reducing downstream costs and protecting product value.

Recommended Testing Strategies for Harvest 2026

1. Risk-Based Sampling

Sampling remains the most critical step in mycotoxin testing.

Because mycotoxins are heterogeneously distributed, poor sampling can introduce greater analytical error than laboratory testing itself.

Recommended practices include:

• Collection of multiple incremental samples
• Representative composite sampling
• Compliance with EU Regulation (EU) 2023/2782 and relevant national standards
• Increased sampling frequency for high-risk regions and commodities

2. Rapid Screening at Intake

Rapid lateral flow and quantitative immunoassay technologies provide immediate decision-making capability at grain reception points.

Benefits include:

• Results within minutes
• Reduced storage of suspect lots
• Immediate segregation decisions
• Lower overall testing costs

Recommended targets:

• Aflatoxin total
• DON
• ZEN
• Fumonisins

3. Laboratory Confirmation

High-risk or positive screening samples should undergo confirmatory testing.

Preferred analytical methods include:

• LC-MS/MS
• HPLC-FLD
• UHPLC-MS/MS

These techniques provide:

• High sensitivity
• Multi-mycotoxin capability
• Regulatory-grade documentation
• Quantification of emerging toxins

4. Multi-Mycotoxin Surveillance Programs

Contamination rarely involves a single toxin.

Modern testing programs should monitor:

5. Storage Monitoring

Testing should not end at harvest.

Post-harvest monitoring should include:

• Moisture control
• Temperature surveillance
• Periodic mycotoxin verification
• Testing before shipment and processing

Storage-related fungal growth can significantly increase contamination levels after harvest.

Integrated Mycotoxin Management Approach

Testing should form part of a broader risk management framework including:

Pre-Harvest Measures

• Selection of resistant varieties
• Crop rotation
• Fungicide programs where appropriate
• Timely harvest

Harvest Controls

• Moisture assessment
• Removal of damaged kernels
• Segregation of suspect lots

Post-Harvest Controls

• Rapid drying
• Aeration
• Continuous monitoring
• Routine testing

Combining preventive measures with analytical verification provides the highest level of protection against mycotoxin-related losses.

Conclusion

The 2026 harvest is expected to present significant mycotoxin challenges driven by increasingly variable climatic conditions and evolving regulatory expectations. Aflatoxins, Fusarium toxins, and emerging mycotoxins remain critical hazards requiring proactive management. Organizations throughout the food and feed chain should implement risk-based sampling, rapid screening technologies, confirmatory laboratory analysis, and continuous storage monitoring. Such integrated testing strategies are essential for ensuring regulatory compliance, protecting public health, and safeguarding the economic value of agricultural commodities.

Keywords

Mycotoxins, Harvest 2026, Aflatoxin Testing, DON, Zearalenone, Fumonisins, Food Safety, Feed Safety, Grain Testing, Risk Management, LC-MS/MS, Rapid Screening, Agricultural Commodities

Field Trial Confirms the Benefits of Pidolin® PCa in Breeder Hens

As breeder hens age, maintaining egg production, shell quality, and flock vitality becomes increasingly challenging. A recent large-scale field trial in the Czech Republic (2025) demonstrates how Pidolin® PCa (calcium pidolate) helps support laying persistence, egg quality, survivability and overall profitability in late-production breeder flocks.

Real Farm Conditions, Real Results

The 49-day trial was conducted under commercial conditions, involving nearly 40.000 breeder hens:

• Control group: Isa Brown, basal diet
• Pidolin® PCa group: Bovans Brown, basal diet + 300 g/t Pidolin® PCa
• Supplementation period: weeks 64–68

All management parameters (housing, temperature, lighting, density) were identical, ensuring supplementation was the key differentiating factor.

Improved Laying Persistence and Egg Output

Despite the advanced age of the flock, hens receiving Pidolin® PCa showed a clear performance advantage:

• +1.2 points laying persistence compared to the control
• +1.5% more eggs selected for incubation
• More stable production with lower variation over time

These results indicate that Pidolin® PCa helps sustain productive performance when natural calcium utilization typically declines.

Beyond productivity, flock health also benefited from supplementation:

• −0.19 percentage points lower mortality during the supplementation period

This reduction reflects improved physiological resilience in aging breeder hens.

Why Pidolin® PCa Works?

Pidolin® PCa combines calcium with pidolic acid, a biologically active molecule that:

• Promotes active calcium transport via arginine supply
• Supports collagen synthesis via proline supply
• Contributes to improved eggshell formation and structural integrity

The trial confirms that these mechanisms translate into measurable on-farm benefits.

Strong Economic Return

Performance gains were accompanied by an excellent financial outcome:

• Net benefit: €0,23 per hen
• ROI: 9:1
• Equivalent to €232 net benefit per 1.000 hens

Even after accounting for the supplementation cost, increased chick output drove a clear return on investment.

Proven Support for Aging Breeder Flocks

Pidolin® PCa is a practical nutritional tool to help breeders stay productive, profitable, and resilient in late lay.

Contact us to learn how we can meet your needs