{"id":1055,"date":"2026-07-27T03:23:23","date_gmt":"2026-07-27T03:23:23","guid":{"rendered":"https:\/\/silage-baler.com\/application\/silage-quality-testing-what-the-numbers-actually-mean\/"},"modified":"2026-07-27T03:23:23","modified_gmt":"2026-07-27T03:23:23","slug":"silage-quality-testing-what-the-numbers-actually-mean","status":"publish","type":"post","link":"https:\/\/silage-baler.com\/es\/application\/silage-quality-testing-what-the-numbers-actually-mean\/","title":{"rendered":"Silage Quality Testing: What the Numbers Actually Mean"},"content":{"rendered":"
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Silage Management \u00b7 Quality Testing \u00b7 Feed Decisions<\/div>\n

Silage Quality Testing: What the Numbers Actually Mean<\/p>\n

A practical guide to reading a forage test report \u2014 translating pH, NH\u2083-N, ME, NDF, ADF, and fermentation acid values into the feeding decisions that actually change what goes in the trough.<\/p>\n<\/div>\n<\/div>\n

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The Test Result That Sits in a Drawer Changing Nothing<\/h2>\n

Australian dairy and beef farmers send more silage samples to forage testing laboratories than ever before \u2014 NIR testing is inexpensive (AUD $40 to $75 per sample), fast (24 to 48 hour turnaround from most laboratories), and widely promoted by agronomists, nutritionists, and feed company representatives. The problem is that a significant proportion of test results are received, filed, and not acted on \u2014 either because the numbers are unfamiliar, because the producer doesn’t know which numbers matter most for their livestock class, or because the nutritional implications are unclear without the context of a full ration calculation.<\/p>\n

This article is a plain-language guide to the numbers that appear on a standard Australian silage forage test report \u2014 what each parameter measures, what the acceptable ranges are for different livestock classes, and what specific feeding or ration decisions each result should trigger. The goal is to convert a test result from a document you file to a tool you use.<\/p>\n

For the production decisions that determine what quality a silage test result will show before it arrives \u2014 including the impact of wrapping quality and fermentation management \u2014 our article on the best silage baler setup for high-volume dairy operations<\/a> covers how production decisions upstream of the test determine what the result can be.<\/p>\n<\/div>\n

\"Silage<\/p>\n

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The Core Parameters: What Each Number Measures<\/h2>\n

1. Dry Matter (DM) \u2014 The Starting Point for Everything<\/h3>\n

DM percentage tells you how much of the bale is actual feed and how much is water. A silage bale at 40% DM (60% moisture) contains 400 kg DM per tonne of fresh weight; a bale at 30% DM (70% moisture) contains 300 kg DM per tonne. All other parameters \u2014 ME, CP, NDF \u2014 are expressed on a DM basis, so the DM figure is the denominator for all nutritional calculations.<\/p>\n

Action trigger: If DM is below 30% (above 70% moisture), the silage was baled too wet and fermentation quality risk is high \u2014 check pH and NH\u2083-N before feeding to sensitive livestock. If DM is above 55% (below 45% moisture), the silage was baled on the dry side and aerobic stability at feedout may be compromised \u2014 open bales close to the daily consumption rate.<\/p>\n

2. pH \u2014 The Primary Fermentation Quality Indicator<\/h3>\n

pH measures the acidity of the silage. Well-fermented silage produced predominantly by lactic acid bacteria has pH 3.8 to 4.5. Higher pH (4.5 to 5.5) indicates incomplete or compromised fermentation \u2014 either because the silage was too dry (above 55% DM) for active fermentation, too wet (below 30% DM) with insufficient WSC, or because the fermentation was dominated by clostridial bacteria producing butyric acid rather than lactic acid.<\/p>\n

\n\n\n\n\n\n\n\n\n
pH Range<\/th>\nFermentation Assessment<\/th>\nLivestock Suitability<\/th>\nAction<\/th>\n<\/tr>\n<\/thead>\n
3.8\u20134.5<\/td>\nExcellent \u2014 lactic acid dominant<\/td>\nAll classes \u2014 no restriction<\/td>\nFeed normally<\/td>\n<\/tr>\n
4.5\u20135.0<\/td>\nAcceptable \u2014 minor clostridial activity<\/td>\nAll classes with monitoring<\/td>\nCheck NH\u2083-N; limit to non-peak animals if high<\/td>\n<\/tr>\n
5.0\u20135.5<\/td>\nPoor \u2014 significant clostridial activity<\/td>\nAvoid peak-lactation dairy, late-preg ewes<\/td>\nCheck NH\u2083-N; feed only to dry\/maintenance stock<\/td>\n<\/tr>\n
>5.5<\/td>\nFailed fermentation<\/td>\nDo not feed to productive livestock<\/td>\nDiscard or compost<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

3. Ammonia Nitrogen (NH\u2083-N) \u2014 The Protein Damage Indicator<\/h3>\n

NH\u2083-N is expressed as a percentage of total nitrogen in the sample. It measures how much of the silage’s protein nitrogen has been broken down into ammonia \u2014 a metabolically useless form for ruminants and a palatability depressant at elevated concentrations. In well-fermented silage, NH\u2083-N below 8% of total N indicates minimal protein degradation. Above 12%, the silage carries measurable palatability reduction and available protein is significantly below what the crude protein figure suggests.<\/p>\n

NH\u2083-N is the most important single indicator of silage feeding value after pH. A silage with CP of 18% but NH\u2083-N of 20% has most of its ‘protein’ in ammonia form \u2014 effectively unavailable to the animal and causing intake depression that reduces the productivity benefit you would expect from an 18% CP feed.<\/p>\n

4. Metabolisable Energy (ME) \u2014 The Productivity Driver<\/h3>\n

ME (MJ\/kg DM) is calculated from the digestibility of the silage’s organic matter. It is the most direct measure of how much energy the animal can extract from the silage. High ME silage (10.0 to 11.5 MJ\/kg DM) supports high production; medium ME (9.0 to 10.0 MJ\/kg DM) supports maintenance to moderate production; low ME (below 8.5 MJ\/kg DM) is inadequate for productive livestock and requires energy supplementation from grain or other concentrates.<\/p>\n

\n\n\n\n\n\n\n\n\n
ME Range<\/th>\nSuitable For<\/th>\nGrain Supplement Required?<\/th>\nTypical Silage Source<\/th>\n<\/tr>\n<\/thead>\n
\u226510.5 MJ\/kg DM<\/td>\nPeak lactation dairy, growing cattle<\/td>\nMinimal or none<\/td>\nEarly-cut ryegrass\/lucerne<\/td>\n<\/tr>\n
9.5\u201310.5 MJ\/kg DM<\/td>\nLactating ewes, growing heifers<\/td>\nSmall allocation<\/td>\nFlag-leaf silage, good ferment<\/td>\n<\/tr>\n
9.0\u20139.5 MJ\/kg DM<\/td>\nDry cows, weaned lambs, maintenance<\/td>\n0.5\u20131.0 kg\/head\/day<\/td>\nMid-season cut, good ferment<\/td>\n<\/tr>\n
<9.0 MJ\/kg DM<\/td>\nDry stock maintenance only<\/td>\n1.5\u20132.5 kg\/head\/day<\/td>\nLate-cut or poor ferment<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

5. NDF and ADF \u2014 The Fibre Quality Indicators<\/h3>\n

Neutral Detergent Fibre (NDF) measures the total structural fibre \u2014 cell wall material including cellulose, hemicellulose, and lignin. Higher NDF reduces voluntary intake because rumen fill from structural fibre is the primary intake regulator in ruminants. NDF below 50% DM indicates a leafy, digestible silage with high voluntary intake potential; NDF above 65% DM indicates a mature, stemmy material with restricted intake potential.<\/p>\n

Acid Detergent Fibre (ADF) measures only the cellulose and lignin fraction \u2014 the least digestible components. ADF correlates inversely with digestibility: high ADF = low digestibility. ADF below 30% DM indicates excellent digestibility; ADF above 40% DM indicates poor digestibility regardless of CP or ME values.<\/p>\n<\/div>\n

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Fermentation Acid Profile: The Advanced Test Parameters<\/h2>\n

Lactic Acid vs. Acetic Acid vs. Butyric Acid \u2014 What Each Means<\/h3>\n

Advanced silage tests from laboratories including Feedtest (Elanco Australia) and Nutrient Advantage report the actual fermentation acid profile \u2014 the concentrations of lactic acid, acetic acid, propionic acid, and butyric acid in the silage DM. These parameters are not on standard NIR tests but are available as add-ons at AUD $25 to $45 additional per sample and provide the most detailed picture of fermentation pathway available without a full microbiology analysis.<\/p>\n

\n\n\n\n\n\n\n\n\n
Acid<\/th>\nGood Silage Range<\/th>\nIndication if Elevated<\/th>\nAction<\/th>\n<\/tr>\n<\/thead>\n
Lactic acid<\/td>\n5\u201310% DM<\/td>\nPrimary fermentation product \u2014 dominant in good silage<\/td>\nHigh is good<\/td>\n<\/tr>\n
Acetic acid<\/td>\n1\u20133% DM<\/td>\nHeterofermentative LAB or aerobic activity<\/td>\nAbove 4%: aerobic stability concern<\/td>\n<\/tr>\n
Propionic acid<\/td>\n<0.5% DM<\/td>\nMinor byproduct \u2014 normal at low levels<\/td>\nHigh: unusual, investigate<\/td>\n<\/tr>\n
Butyric acid<\/td>\n<0.1% DM<\/td>\nClostridial fermentation marker<\/td>\nAny detectable level: poor quality batch<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Butyric acid is the key diagnostic parameter for clostridial fermentation. Any detectable butyric acid (above 0.05% DM) in a silage sample indicates that clostridial bacteria were active during fermentation \u2014 and that NH\u2083-N is likely elevated, palatability is reduced, and the batch should be assessed before feeding to peak-productivity livestock.<\/p>\n<\/div>\n

\"9YCM-850<\/p>\n

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How to Use Test Results in Practical Feeding Decisions<\/h2>\n

The Ration Check: Four Questions the Test Result Should Answer<\/h3>\n
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1<\/div>\n
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Is the ME adequate for the stock class I’m feeding?<\/div>\n

Compare the test ME to the target ME for your stock class. If the silage ME is below target by more than 0.5 MJ\/kg DM, calculate the additional grain needed per head per day to close the energy gap. A Holstein cow at peak lactation needs 10.5 MJ\/kg DM silage as a minimum for silage to carry the roughage fraction of her ration without large grain allocations.<\/p>\n<\/div>\n<\/div>\n

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2<\/div>\n
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Is the CP adequate, and is the NH\u2083-N below 8%?<\/div>\n

If CP is adequate (above 14% for dairy) but NH\u2083-N is above 10%, the available protein is significantly below the headline CP figure. Adjust the protein supplement allocation upward to compensate for ammonia-N that will not be used by the animal. If CP is below target regardless of NH\u2083-N, add rumen-degradable protein supplement.<\/p>\n<\/div>\n<\/div>\n

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3<\/div>\n
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Is the NDF low enough for my target voluntary intake?<\/div>\n

For peak-lactation dairy, NDF above 55% starts restricting voluntary intake below the 20 to 24 kg DM\/day target. If NDF is high, supplement with a lower-NDF, higher-ME complementary ingredient (grain, distillers grains, beet pulp) to maintain total energy intake without relying on higher roughage volume.<\/p>\n<\/div>\n<\/div>\n

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4<\/div>\n
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What is the pH, and does it restrict which stock class can safely receive this batch?<\/div>\n

pH above 5.0 restricts the batch to dry\/maintenance stock only. pH 4.5 to 5.0 allows all stock classes with monitoring. pH below 4.5 is unrestricted. Use this determination to assign batches to stock pens before feedout begins \u2014 not after intake problems emerge.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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Frequently Asked Questions<\/h2>\n
\nHow many bales should I sample from a single cut for a reliable result?<\/span>+<\/span><\/summary>\n
Sample 1 bale for every 50 to 80 bales of similar production origin (same paddock, same cutting day, same baling conditions). For a 400-bale cut from a single paddock, 5 to 8 representative samples provide a statistically reliable picture of average quality. Use a dedicated silage bale coring tool (a long hollow probe driven through the bale end face) rather than pulling surface material \u2014 the surface sample represents the outer layers, which are the lowest-quality part of the bale, not the average interior.<\/div>\n<\/details>\n
\nWhen is the right time to test silage after baling?<\/span>+<\/span><\/summary>\n
Minimum 21 days after baling \u2014 before this point, fermentation is still active in most bales and the pH, NH\u2083-N, and acid profile are still changing. Testing at 14 days or earlier produces results that do not represent the final fermentation outcome. Optimal testing time is 28 to 45 days post-baling, when fermentation is complete and the result reflects what the animal will actually receive when the bale is opened.<\/div>\n<\/details>\n
\nMy silage test shows 15% CP but cattle intake is lower than expected. What is wrong?<\/span>+<\/span><\/summary>\n
Check NH\u2083-N. High CP with low intake and reduced productivity is the classic profile of clostridially spoiled silage where the headline CP is accurate but a large proportion of it is in the ammonia form \u2014 which depresses intake through its odour and metabolic effects. If NH\u2083-N is above 12% of total N, the effective available protein is closer to 8 to 10% than 15%, and the intake depression is the animal’s normal response to ammonia-contaminated feed.<\/div>\n<\/details>\n
\nDo I need a full acid profile test or is standard NIR sufficient?<\/span>+<\/span><\/summary>\n
Standard NIR (DM, CP, ME, NDF, ADF, pH, NH\u2083-N) is sufficient for routine silage management and feeding decisions in most operations. The full fermentation acid profile (lactic, acetic, butyric) adds value when: you are diagnosing a batch with lower-than-expected performance despite acceptable pH and NH\u2083-N, you want to assess aerobic stability risk before opening high-value batches in warm weather, or you are calibrating a new silage production protocol and want to verify fermentation pathway.<\/div>\n<\/details>\n
\nCan I compare silage test results between different laboratories?<\/span>+<\/span><\/summary>\n
With caution. NDF, ADF, DM, and CP values from NATA-accredited Australian laboratories (Nutrient Advantage, Feedtest\/Elanco, ALS Agriculture) are directly comparable because they use standardised AOAC methods. ME values may vary by up to 0.3 to 0.5 MJ\/kg DM between laboratories because ME is calculated from digestibility using different regression equations at different labs \u2014 confirm which ME equation each laboratory uses before comparing results across labs. pH is universal and directly comparable across laboratories.<\/div>\n<\/details>\n<\/div>\n

\"9YG-1.25A\"9GQY-3.2<\/p>\n

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Consistent silage production quality \u2014 starting from baling and wrapping \u2014 is what gives the forage test result its best possible starting point. The 9YCM-850 bundling film wrapping machine<\/a> applies a programmable, consistent layer count to every bale \u2014 removing the operator counting variation that causes under-wrapped bales whose fermentation the test result will later reflect. Starting from a well-wrapped bale gives the fermentation process its best possible substrate; the forage test simply confirms how well it succeeded.<\/p>\n<\/div>\n

EverPower Baling Machinery \u00b7 Condell Park NSW 2200<\/div>\n

Discuss Your Silage Quality Targets<\/h2>\n

Tell us your stock class, production targets, and current test results \u2014 we’ll help translate the numbers into the feeding and production decisions that improve your programme.<\/p>\n

Request a Quote<\/a> About EverPower<\/a><\/div>\n
+61 2 9708 3322<\/a>  |  \u2709 sales@silage-baler.com<\/a><\/div>\n<\/div>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"

Silage Management \u00b7 Quality Testing \u00b7 Feed Decisions Silage Quality Testing: What the Numbers Actually Mean A practical guide to reading a forage test report \u2014 translating pH, NH\u2083-N, ME, NDF, ADF, and fermentation acid values into the feeding decisions that actually change what goes in the trough. The Test Result That Sits in a […]<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[35],"tags":[],"class_list":["post-1055","post","type-post","status-publish","format-standard","hentry","category-applications"],"_links":{"self":[{"href":"https:\/\/silage-baler.com\/es\/wp-json\/wp\/v2\/posts\/1055","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/silage-baler.com\/es\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/silage-baler.com\/es\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/silage-baler.com\/es\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/silage-baler.com\/es\/wp-json\/wp\/v2\/comments?post=1055"}],"version-history":[{"count":0,"href":"https:\/\/silage-baler.com\/es\/wp-json\/wp\/v2\/posts\/1055\/revisions"}],"wp:attachment":[{"href":"https:\/\/silage-baler.com\/es\/wp-json\/wp\/v2\/media?parent=1055"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/silage-baler.com\/es\/wp-json\/wp\/v2\/categories?post=1055"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/silage-baler.com\/es\/wp-json\/wp\/v2\/tags?post=1055"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}