# Forage Testing and Feed Sampling Plan ## Key Takeaways - **Representative sampling is paramount:** Employ coring tools for hay (minimum 10-20 cores per lot) and collect multiple subsamples across the exposed face of silage after removing spoiled material to ensure nutrient analysis accurately reflects the entire feed source, mitigating bias from surface variability. - **Laboratory selection and analysis are critical:** Choose accredited laboratories utilizing validated methods such as wet chemistry for precise fiber (e.g., amylase-treated NDF for heat-damaged forages) and protein determination, and specify analyses relevant to animal class and production stage. - **Nutrient interpretation informs ration adjustment:** Compare laboratory results for dry matter, crude protein, fiber fractions (NDF, ADF), and minerals against established animal requirements and forage maturation benchmarks to guide precise adjustments in concentrate and supplement inclusion, optimizing rumen health and production targets. - **Systematic record-keeping is essential for trend analysis:** Document sample identifiers, test results, and subsequent ration changes for at least two production cycles to track forage quality trends, identify potential harvest or storage issues, and support health investigations. - **Forage testing integrates with broader health and biosecurity protocols:** Accurate nutrient assessment prevents metabolic disorders and supports biosecurity by requiring clean sampling equipment to prevent pathogen transmission, aligning with WOAH standards for safe feed practices. - **Veterinary consultation is vital for complex interpretations and escalations:** When forage test results are inconsistent with visual assessment, animal performance, or when suspected toxicities (e.g., nitrates, mycotoxins) are present, professional veterinary input is required for accurate diagnosis and intervention. --- Forage testing and a structured feed sampling plan provide the foundation for evidence-based ration formulation in livestock operations. A systematic approach to collecting, submitting, and interpreting forage samples allows producers and veterinarians to match feed nutrients to animal requirements, prevent production diseases, and manage feed costs. This article outlines the critical steps in establishing a sampling program, from representative field collection to laboratory communication and result application. ## At a Glance | Component | Description | Key Consideration | |-----------|-------------|-------------------| | Sampling Protocol | Systematic collection of forage samples that represent the entire feed source | Use coring tools for hay, follow transect patterns for pasture, collect at consistent depth and location | | Laboratory Selection | Choosing an accredited laboratory with appropriate analytical methods | Confirm the laboratory uses methods such as near-infrared spectroscopy or wet chemistry for fiber and protein analysis | | Nutrient Analysis | Determination of dry matter, crude protein, fiber fractions (NDF, ADF), and minerals | Include amylase-treated NDF for heat-damaged forages as per collaborative study methods (Gravimetric determination of amylase-treated neutral detergent fiber) | | Result Interpretation | Comparing test values to animal nutrient requirements and expected forage quality | Recognize that forage maturation affects nutrient content (A Multi-Scale Test Of The Forage Maturation Hypothesis) | | Ration Adjustment | Modifying supplement and concentrate inclusion based on forage analysis | Adjust energy and protein sources to maintain rumen health and production targets | | Record Keeping | Documenting sample identifiers, test results, and ration changes over time | Maintain records for at least two production cycles to track trends and support health investigations | ## System Context for Forage Testing Forage testing operates within a broader production and health management system. The [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) guidance underscores that feed quality directly influences livestock productivity and disease resistance, while [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) standards for safe feed practices emphasize the role of accurate nutrient assessment in preventing metabolic disorders. The [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) resource and the [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) provide frameworks for integrating feed quality monitoring into national animal health surveillance. Within this context, a forage testing plan is not an isolated activity but a component of ongoing herd health and production management. Decisions regarding sampling frequency, laboratory choice, and nutrient analysis must align with herd size, forage type, and production goals. ## Planning Decisions for a Sampling Program ### Factors Influencing Sampling Frequency and Scope The variability in forage nutrient content across fields, harvests, and storage conditions requires a planned sampling schedule. For hay and silage, sample each cutting or lot separately, especially when forage maturation stages differ, as this directly affects fiber and protein content (A Multi-Scale Test Of The Forage Maturation Hypothesis). For pasture-based systems, sample representative sites at key growth stages to capture changes in digestibility. Budget constraints and labor availability influence how many samples can be processed, but reducing sample numbers risks inaccurate ration adjustments that could lead to suboptimal production or increased disease risk as noted in [PubMed record 42440396](https://pubmed.ncbi.nlm.nih.gov/42440396/) livestock management reviews. ### Budget and Resource Allocation Allocate resources for sample collection equipment such as forage probes, moisture-proof bags, and shipping materials. Laboratory analysis costs vary by method and number of analytes. Include a margin for repeat analyses when results appear inconsistent with visual assessment, for instance when heat damage is suspected. [PubMed record 42430950](https://pubmed.ncbi.nlm.nih.gov/42430950/) reviews indicate that investment in accurate testing reduces overall feed cost by avoiding over-supplementation and preventing health issues. The [Merck Veterinary Manual](https://www.merckvetmanual.com/) provides guidance on expected nutrient ranges for common forages, aiding in budget planning. ## Core Management Framework for Feed Sampling ### Representative Sampling Techniques Representative sampling requires that the collected material genuinely reflects the average nutrient content of the feed source. For baled hay, use a forage core probe at least 12 to 18 inches long to sample multiple bales from each lot, taking cores from the center of the flat end of each bale. For silage, sample from the face of the silage pile or bunker after removing spoiled surface material, taking multiple cores across the exposed face. For pasture, use a simple randomized transect, collecting plant material at grazing height. [PubMed record 42426786](https://pubmed.ncbi.nlm.nih.gov/42426786/) provides evidence that improper sampling techniques introduce variability that compromises the entire testing process. ### Laboratory Communication and Analysis Once samples are collected, package them in sealed, moisture-proof bags and ship promptly to the laboratory with a completed submission form. Clearly indicate the sample type, crop species, and expected use (e.g., beef cattle, dairy cows). Specify required analyses: dry matter, crude protein, neutral detergent fiber (NDF), acid detergent fiber (ADF), and minerals such as calcium, phosphorus, and potassium. For heat-damaged forages, request amylase-treated NDF as described in the collaborative study (Gravimetric determination of amylase-treated neutral detergent fiber). Communicate any concerns about potential contamination or storage issues, as these affect method selection. The laboratory should provide a report with both measured values and interpretation guidelines. For further clinical context, refer to the [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) resources and the [Merck Veterinary Manual](https://www.merckvetmanual.com/) for management of forage-related health problems. ## Representative Sampling Accurate forage testing begins with a sampling protocol that captures the true nutrient composition of a feed lot, bunk, or storage structure. The objective is to collect a set of subsamples that, when combined and submitted, reflect the bulk material without systematic bias. A single grab sample, especially from the top of a silo or the outer layer of a bale, can overestimate or underestimate protein, fiber, and moisture content by a wide margin. Recommended practice involves using a core sampler that penetrates at least halfway into a bale or silage face, collecting multiple cores from different locations and depths. For hay, a minimum of 15 to 20 cores taken from randomly selected bales in a lot is standard, though the exact number depends on lot uniformity and the statistical confidence required. The cores are combined into one composite sample, mixed thoroughly, and then reduced to a laboratory-sized aliquot. The sampling plan must account for storage conditions and feed,out patterns, for example, silage that has been exposed to air for several days near the feedout face may have undergone spoilage and should be sampled separately. Handling and transporting the sample in a sealed, cool container preserves its composition until analysis. The [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) emphasizes that sample integrity directly affects the reliability of subsequent nutritional decisions. ## Laboratory Communication Once the composite sample arrives at the analytical laboratory, clear communication between the producer, nutritionist, and lab personnel is essential to ensure that the correct tests are ordered and the results are correctly interpreted. The submission form should include the sample type (hay, silage, fresh forage, byproduct), the intended animal class (e.g., lactating dairy cow, growing steer, dry ewe), and any special requests such as analysis for mycotoxins, minerals, or starch. The laboratory should be accredited under a recognized quality system, such as those referenced in the [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/), which provides standards for sample handling, data integrity, and inter,laboratory comparability. The producer should also define the analytical platform, choosing between near,infrared reflectance (NIR) and wet chemistry methods. NIR is rapid and cost,effective for routine nutrients, but wet chemistry remains the reference for precise fiber fractions and minerals. Communication of turnaround time and the format of results (e.g., as,fed vs. dry,matter basis) prevents confusion during ration formulation. ## Result Interpretation Laboratory reports typically include dry matter, crude protein, neutral detergent fiber (NDF), acid detergent fiber (ADF), and total digestible nutrients (TDN) or net energy values. Interpretation requires comparing these values to established benchmarks for the target production stage, also to a generic standard. The gravimetric determination of amylase,treated NDF, as validated in collaborative studies [Gravimetric determination of amylase,treated neutral detergent fiber in feeds with refluxing in beakers or crucibles](https://api.elsevier.com/content/abstract/scopus_id/0040673824), provides a consistent measure of fiber that correlates with intake potential. A high NDF may limit dry matter intake in high,producing animals, while a low ADF can indicate a rapidly fermentable forage that may cause ruminal acidosis if not balanced with sufficient physically effective fiber. Mineral analysis, particularly calcium, phosphorus, potassium, and magnesium, must be evaluated against dietary requirements. For example, the ratio of potassium to magnesium can influence the risk of grass tetany in grazing livestock. The interaction of forage nutrients with supplemental feeds is captured in the ration model, but the practitioner should examine results for outliers that suggest sampling error or spoilage. When results fall outside expected ranges, eschewing automatic ration adjustments and resampling or consulting a [veterinary nutritionist](/blog/careers/becoming-a-veterinary-nutritionist-education-certification-and-practice) is prudent. Uncertainty in interpretation is reduced by maintaining a multi,year database of forage analyses for the same farm, as recommended by [FAO Livestock Management Guidance](https://www.fao.org/animal-production/en/), which notes that historical trends often reveal handling or harvest problems before they cause clinical disease. ## Ration Decisions Forage analysis informs the base ration, which then drives selection of supplemental grains, protein meals, fats, and mineral premixes. The distinction between energy and protein supply must be aligned with the animal’s physiological state. In lactating dairy cows, the forage portion typically provides 40% to 60% of total dry matter, and its fiber content must be adequate to maintain rumen health while not restricting energy intake. For growing beef cattle, the forage quality determines the need for high,energy concentrates. The forage-to-concentrate ratio is adjusted according to forage NDF and TDN, but specific numerical targets are beyond the scope of this article and must be determined using a validated ration formulation program. The [Merck Veterinary Manual](https://www.merckvetmanual.com/) offers guidance on interpreting forage nutrients in relation to metabolic disorders such as hypocalcemia and ketosis. Ration decisions should also consider the economic trade,off of supplementing a low,quality forage versus purchasing higher,quality forage. In all cases, the ration must be recalculated each time a new forage analysis is obtained, as nutrient composition can shift between harvests and even within a single storage structure. ## Sample Records Systematic recordkeeping of forage samples and their analytical results is a pillar of modern herd management. Each sample should be assigned a unique identifier that links to the harvest date, field, storage method, and the bale or silo location. The laboratory report should be retained in a structured database or a simple spreadsheet, along with notes on the animal’s performance (milk yield, weight gain, health events) during the feeding period of that forage. These records allow the manager to correlate forage quality with production outcomes and to identify non,nutritional factors such as mycotoxin contamination or excessive moisture that may have gone undetected in a single analysis. The [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) resources emphasize that recordkeeping also supports traceability in the event of a feed,related disease investigation. When records reveal a pattern of declining forage quality over successive harvests, the producer can adjust field management, including timing of cutting or use of preservatives. Regular auditing of these records, perhaps at each feeding season change, reduces the risk of feeding a forage that has moldered or lost nutritional value during prolonged storage. ## Facilities, Environment, and Production Stage Decisions The sampling plan must reflect the facility environment. Forages stored in outdoor stacks, covered bunkers, or upright silos face different spoilage risks and may require separate sampling strategies. Bunk silos exposed to rain and wind can have dry, deteriorated outer layers that must be removed before feeding, these layers should be sampled separately to assess loss. The environment also influences the schedule of sampling: during hot, humid weather, rapid mold growth can alter nutrient profiles, so more frequent sampling is warranted. Production stage decisions,such as transitioning cows from the dry period to lactation,demand forage testing at each stage because the same forage may be acceptable for a dry cow but inadequate for a high,producing cow. The [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) guidelines advise that forage quality be evaluated at least once per batch and more often if the batch will be fed over many months, as composition can change with continued fermentation in silage or with aerobic deterioration in hay. ## Welfare, Worker and [Food Safety](/knowledge/bacteria/livestock-bacteria/cooking-chicken-bacteria-prevention) Nutritional imbalances from misinterpreted forage tests can lead to metabolic diseases that compromise animal welfare, such as ruminal acidosis, laminitis, hypocalcemia, or ketosis. These conditions also cause suffering but also reduce productivity and increase veterinary costs. The veterinarian and nutritionist share responsibility for ensuring that forage analysis is used to avoid such outcomes. Worker safety is relevant during sample collection: entering a silo can expose personnel to hazardous gases such as nitrogen dioxide, and handling moldy hay poses respiratory risks. Proper ventilation, personal protective equipment, and training on confined space entry are essential. Food safety concerns emerge when forages contain pesticide residues, mycotoxins, or pathogens that can transfer into milk or meat. The [WOAH standards](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) include guidance on testing for biological contaminants, and the sample record should flag any analysis that shows elevated levels of aflatoxin or ergot alkaloids, which then require immediate removal from the feed chain. ## Failure Patterns and Practical Monitoring Common failures in forage testing and feeding include inconsistent sampling depth, infrequent testing, and reliance on outdated analyses. A typical error is submitting a sample from only the first bales of a harvest, ignoring the variability across the field. Another is failing to adjust the ration when a new silage face is opened, the analysis from the top of the silo may not represent the material at the bottom. Practical monitoring requires a schedule: for bunk silos, sample at each new layer or every two weeks, for bales, sample every 50 bales or per lot change. Comparisons of laboratory results over time, using the farmer’s own database, provide the strongest basis for adjustments. When performance fails to match expectations despite adequate forage testing, the practitioner should examine water quality, feed mixing accuracy, and animal behavior,factors that can override forage composition. The [PubMed review of livestock management](https://pubmed.ncbi.nlm.nih.gov/42440396/) underscores that nutritional assessments are most valuable when integrated with observations of body condition, rumen fill, and fecal consistency. Finally, a collaborative relationship between the producer, veterinarian, and certified laboratory creates a feedback loop that converts forage test data into actionable, welfare,conscious management decisions. ## Health Observation and Biosecurity in Feed Management Forage testing supports health monitoring by revealing nutrient imbalances that predispose animals to metabolic disorders. Low fiber digestibility can contribute to rumen acidosis, while excess potassium relative to calcium and magnesium increases risk of hypomagnesemic tetany in lactating ruminants. Daily observation of body condition, rumen fill, manure consistency, and milk production or weight gain provides immediate feedback on ration adequacy. The Merck Veterinary Manual emphasizes that clinical signs such as reduced feed intake, poor coat condition, or diarrhea warrant prompt investigation of forage quality and ration composition. Routine health checks should be documented and cross-referenced with test results to identify trends. Biosecurity extends to feed sampling and storage. Sampling equipment must be clean and dedicated to feed use to prevent cross,contamination between forages, concentrates, and potential pathogens. The WOAH Terrestrial Animal Health Code outlines general principles for preventing disease introduction through feed, including segregation of raw materials and regular cleaning of storage areas. Forages stored in bales or silage should be protected from wildlife, rodents, and standing water to reduce spoilage and mold growth. Mycotoxin contamination, though not detected by standard proximate analysis, can be suspected when animals show unexplained feed refusal, immunosuppression, or reproductive failure. Laboratory testing for specific mycotoxins should follow a veterinary diagnosis. ## Diagnostic Escalation and Veterinary Consultation Forage analysis provides objective data, but results carry inherent uncertainty from sampling error, laboratory variation, and biological variability among animals. A single composite sample represents a batch but may miss pockets of mold or spoiled material. When test results deviate markedly from expected values, or when animal performance does not match predicted outcomes, a veterinarian should be consulted. USDA APHIS livestock disease guidance recommends that unexplained morbidity or mortality be investigated with laboratory diagnostics beyond forage testing. The veterinarian can integrate forage results with herd health records, blood chemistry, and necropsy findings to rule out nutritional deficiencies or toxicities. Professional escalation is warranted in cases of suspected nitrate poisoning, cyanide from sorghum forages, or ionophore carryover. These conditions require rapid intervention and confirmatory testing that standard forage labs may not offer. For nitrate toxicity, the veterinarian can guide sample collection from suspect plants and interpret threshold concentrations relative to animal risk factors. Similarly, when forage test results show marginal energy or protein levels in a herd with declining condition, the veterinarian can calculate supplementation needs and monitor response. Uncertainty in forage digestibility estimates, especially for tropical grasses, should be acknowledged. The FAO Animal Production and Health guidance notes that feeding standards are approximations and must be adjusted based on observed animal response. ## Sustainability through Nutrient Management Forage testing contributes to sustainable livestock production by optimizing nutrient use and reducing waste. Feeding forages that precisely match animal requirements lowers nitrogen and phosphorus excretion, decreasing environmental loading. The concept of phosphorus use efficiency, discussed in the literature on improving phosphorus management, applies to rations where forage mineral content is known. Over,supplementation of phosphorus can be avoided when test results show adequate forage levels. Conversely, identifying deficient forages allows targeted supplementation instead of blanket additions. Efficient forage testing also supports pasture management. For grazing systems, testing at different growth stages helps schedule grazing to capture peak digestibility. The forage maturation hypothesis, as tested in ungulate populations, shows that animal preference and intake decline as plants mature. Regular sampling and laboratory communication with a forage testing laboratory enables producers to adjust stocking rates or supplementary feeding. The USDA National Animal Health Monitoring System includes feed management as a component of herd health, recognizing that precise feeding reduces morbidity and mortality, which in turn lowers veterinary costs and improves resource efficiency. ## Frequently Asked Questions **1. How often should I test my forages?** Testing should be done at harvest for each cutting or lot. For hay, test within two months of baling. For silage, test after fermentation is complete, typically four weeks post,filling. Annual testing for core nutrients is a minimum standard. **2. Can I rely on book values instead of testing?** Book values provide general estimates but cannot account for local soil, climate, and harvest conditions. Actual testing is necessary for accurate ration formulation and health management. **3. What is the most important nutrient to test?** For ruminants, crude protein and neutral detergent fiber are foundational. For dairy cows, starch and non,fiber carbohydrates are also critical. Always request amylase,treated neutral detergent fiber for accuracy. **4. How do I ensure a representative sample?** Use a core sampler, take at least 10 subsamples from different bales or sections of a silage face, mix thoroughly, and submit about 500 grams. Avoid hand,grabbing because surface material is not uniform. **5. What should I do if my test shows a nutrient deficiency?** First confirm the deficiency with a veterinarian or nutritionist. They can calculate supplementation with concentrate, minerals, or alternative forages. Retest the new ration to verify correction. **6. Can mold be detected by a standard forage test?** Standard analysis does not measure mold or mycotoxins. If spoilage is suspected, request specific mycotoxin tests based on visual mold and animal signs. Consult a veterinarian for test selection. **7. How do I communicate with the laboratory?** Provide a clear sample identifier, forage type, stage of harvest, and any suspected contaminants. Ask about analytical methods, especially for fiber and minerals. Request a wet chemistry panel instead of near,infrared for critical decisions. **8. Should I test manure along with forages?** Manure testing can complement forage analysis by indicating actual digestibility and mineral excretion. This is especially useful when unexplained performance issues persist. ## Educational Veterinary Notice Forage testing is a management tool, not a substitute for veterinary oversight. Ration adjustments based on forage analysis should be implemented gradually and monitored for animal response. Discrepancies between test results and observed health require professional investigation. Veterinary consultation ensures that nutritional changes do not mask underlying disease or create new imbalances. Producers are encouraged to maintain a continuous dialogue with their herd veterinarian and laboratory to refine feeding programs over time. ## Related Farming Guides - [How To Write A Farm Biosecurity Plan](/knowledge/animal-farming/farm-management/how-to-write-a-farm-biosecurity-plan) - [Livestock Farm Record Keeping System](/knowledge/animal-farming/farm-management/livestock-farm-record-keeping-system) - [Livestock Emergency Preparedness Plan](/knowledge/animal-farming/farm-management/livestock-emergency-preparedness-plan) - [Farm Health Intelligence Observation Records Biosecurity Diagnostics And Veterinary Escalation](/knowledge/animal-farming/farm-management/farm-health-intelligence-observation-records-biosecurity-diagnostics-and-veterinary-escalation) - [Animal Welfare Audits Building A Useful Farm Program](/knowledge/animal-farming/farm-management/animal-welfare-audits-building-a-useful-farm-program) ## Related Clinical & Scientific Guides * [Animal Welfare Audits: Building a Useful Farm Program](/knowledge/animal-farming/farm-management/animal-welfare-audits-building-a-useful-farm-program) * [Total Mixed Ration (TMR) for Dairy: Mixing and Feeding Management](/knowledge/animal-farming/farm-management/total-mixed-ration-dairy-mixing-feeding) * [Feed Additives for Livestock: Probiotics, Enzymes, and More](/knowledge/animal-farming/farm-management/feed-additives-livestock-probiotics-enzymes) ## References and Further Reading - [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) - [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) - [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) - [Merck Veterinary Manual](https://www.merckvetmanual.com/) - [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) > This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.