This publication has been developed to help livestock producers interpret feed analysis results, which can help them in planning rations

DuPonte, Michael W.

ScholarSpace at University of Hawai'i at Manoa

Livestock are most productive when fed a ration that meetstheir nutritional needs. Laboratory analysis of feeds is thebest indicator for predicting animal performance on a rationbefore it is fed. This publication has been developed to helplivestock producers interpret feed analysis results, which canhelp them in planning rations. Livestock feed analyses pro-vide producers with useful data that can help to• determine the nutrient content of a mixed feed or a particu-lar ration component• decrease feed costs through lower-cost rations and moreefficient utilization• evaluate forage production practices such as plant speciesselections, fertilizer schedules, and time of harvest (age ofregrowth)• set and monitor nutrient standards for local and importedfeeds and feed by-products for marketing purposesThe results of the analysis can only be useful when the sampletested truly represents the lot of feed that the animals will eat.Poor sampling technique results in misleading feed analysisvalues, which may lead to increased feed costs, reduced ani-mal performance, and economic loss. For further assistance inusing livestock feed analysis results to maximum benefit, con-tact your local Cooperative Extension Service livestock agent.Michael W. DuPonteCooperative Extension Service, HiloLivestock Feed AnalysisHow to Interpret the ResultsPublished by the College of Tropical Agriculture and Human Resources (CTAHR) and issued infurtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperationwith the U.S. Department of Agriculture. Charles W. Laughlin, Director and Dean, CooperativeExtension Service, CTAHR, University of Hawaii at Manoa, Honolulu, Hawaii 96822.An Equal Opportunity / Affirmative Action Institution providing programs and services to thepeople of Hawaii without regard to race, sex, age, religion, color, national origin, ancestry, dis-ability, marital status, arrest and court record, sexual orientation, or veteran status.Glossaryantioxidant: a feed additive that inhibits one of the chemical re-actions (oxidation) in fats that occur in the presence of oxygen,heat, or light and cause rancidity.macrominerals: those minerals found in an animal’s body in con-centrations higher than 100 ppm—they are calcium (Ca), phos-phorus (P), magnesium (Mg), potassium (K), chlorine (Cl), so-dium (Na), and sulfur (S), and are usually expressed as percent ofdry matter.microminerals: those minerals found in an animal’s body in con-centrations less than 100 ppm; just as important as macromineralsin maintaining health—they are copper (Cu), iron (Fe), zinc (Zn),selenium (Se), fluorine (Fl), manganese (Mn), cobalt (Co), iodine(I), molybdenum (Mo), nickel (Ni), and silicon (Si).monogastric: a type of digestive system consisting of “one stom-ach”—includes humans, swine, poultry, horses, rabbits, dogs, andcats; monogastrics have limited ability to digest fiber and non-pro-tein nitrogen sources; dietary starch and amino acids are essential.ruminant: a type of digestive system consisting of a multicompart-mental stomach including a forestomach (rumen, reticulum, andomasum) and an abomasum (true stomach)—includes cattle, sheep,goats, buffalo, and deer. Ruminants’ ability to digest fiber and usenon-protein nitrogen sources is excellent.non-protein nitrogen (NPN): compared to true protein, this frac-tion of the “crude protein” value refers to any nitrogen (N) whichis not in the form of chains of amino acids—includes ammonia,ammonium phosphate, urea, and dietary nucleic acids. NPN is mosteffectively used by ruminants with a functioning rumen (i.e., notthose suckling milk) and requires the presence of a readily avail-able dietary carbohydrate source, such as molasses or grain.true protein: compared to non-protein nitrogen, this fraction ofthe crude protein consists of long chains of amino acids linkedtogether; essential for diets of monogastrics.Cooperative Extension ServiceThis chart shows how the various nutrient componentsof a livestock forage or feedstuff are related to the valuesobtained from a livestock feed analysis. Some of the termsare defined on the back panel of this publication, and thecomponents are described on the inside page.Livestock feed analysis services are available from theCTAHR Agricultural Diagnostic Service Center throughyour local Cooperative Extension Service office, or fromother commercial laboratories.ORGANIC INORGANICMATTER MATTERMINERALS ASHTOTAL NITROGEN CRUDE PROTEINTRUE PROTEINNON-PROTEIN NITROGENFATS AND OILS ETHER EXTRACT orCRUDE FATCARBOHYDRATESCRUDE FIBER,NEUTRAL DETERGENT FIBER,ACID DETERGENT FIBER,CELLULOSE, and LIGNINNITROGEN-FREE EXTRACT(calculated)Correspondinganalysis orcalculated valueFeedcomponentDRY MATTER MOISTURE DRY MATTERSOLUBLE: STARCHESand SUGARS(plant cell solubles)INSOLUBLE: FIBER(plant cell wall)How does it affect a feed’s composition?DM increases with plant age when harvested.The lower the DM, the more moisture ispresent, and the lower is the nutrient densityin the fresh feed. Also, high moisture maydecrease the keeping quality of a feed(through molding) unless it is made into si-lage.Ash is not digestible by animals. High ashcontent of feeds may dilute the amount ofnutrients available to the animal. Bone con-tent of feeds of animal origin can contributeto ash content. If a plant feed is high in ashcontent, it may be due to soil contaminationduring harvest of the plant material.CP content of plants peaks at about 4–6weeks of age, then begins to decline quickly.Legumes such as alfalfa, koa haole, and clo-vers are generally higher in protein thangrasses and other forages. Seed oil mealshave higher CP values than whole grains. Theprotein quality of grasses declines more rap-idly than that of legumes with plant age, andtropical forages decline more rapidly withplant age than temperate forages.EE is usually higher in meat and fish by-products and whole seeds. If a feed is highin fat, it may be susceptible to rancidity,which causes off-flavors, low palatability,and potential toxic effects. Usually an anti-oxidant  such as Vitamin E is added to pre-vent a feed from becoming rancid.Crude fiber is the poorly digested compo-nent of a feed. It is made up of plant struc-tural carbohydrates such as cellulose andhemicellulose; it also contains some lignin.NDF content increases as plants mature. Al-though feeds from animal tissue (fish meal,meat and bone meal, milk, etc.) do not con-tain fiber, they may contain small amountsof NDF due to ash and other insoluble com-ponents.ADF content increases as the plant maturesand is generally higher in legumes thangrasses of the same age. For any givensample, ADF will be lower than NDF con-tent and the difference between the two re-flects the amount of hemicellulose present.Feeds high in fiber generally have high cel-lulose contents. Cellulose generally has lowdigestibility in nonruminants, and high lev-els may reduce the digestibility of other nu-trients in a ration.Lignin is found in straws, hulls, and over-mature hays. It is essentially indigestible byall livestock.NFE is made up primarily of readily avail-able carbohydrates, such as sugars andstarches; this fraction may also containsulubilized hemicellulose and lignin.What does it mean?DM = Dry MatterDM is the percentage of the feed that is notwater (moisture). Fresh grass has highermoisture content and lower DM content com-pared to hay.Ash = total inorganic matterAsh is a measure of the total mineral contentof the feed, but it does not tell us how muchof each mineral is present.CP = Crude ProteinCP is an estimate of the level of protein inthe feed based on the amount of nitrogenpresent. Since some, but not all, of the nitro-gen is in the form of true protein , it is termed“crude” protein. CP also does not give indi-vidual amino acid profiles.EE = Ether ExtractEE, also termed crude fat, is the amount offat and fat-soluble components in a feed. Inaddition to fats and oils, it includes plant pig-ments (chlorophyll, xanthophylls, carotene)and fat-souble vitamins (A, D, E, K), but itdoes not tell us how much of each vitaminor fatty acid is present.CF = Crude FiberCF is the insoluble carbohydrate remainingin the feed analysis process after the sampleis boiled in weak acid and alkali.NDF = Neutral Detergent FiberThe NDF value is the percent of total fiberin the feed. NDF is the plant cell wall com-ponents: cellulose, hemicellulose, lignin,silica, insoluble CP, and ash. Analysis forNDF, along with ADF, cellulose, and lignin,is replacing  the older, more variable crudefiber analysis.ADF = Acid Detergent FiberThe ADF value is the percent of the least di-gestible parts of cell walls: cellulose, lignin,silica, insoluble CP, and ash.CelluloseCellulose is the principal constituent of plantcell walls.LigninLignin is not true carbohydrate; it is a pro-tective coating on the cellulose-hemicellu-lose structure of plant tissues, which appar-ently protects them from bacterial attack.NFE = Nitrogen free extractNFE is a calculated value: the originalsample weight minus the sum of weights ofwater, ether extract, crude protein, crude fi-ber, and ash.How can I use this information?Expressing nutrients on a dry-matter basisallows comparison among feeds by correct-ing for “as-fed” moisture. Diets are formu-lated on DM basis, but ingredients areweighed out or mixed on an as-fed basis.When fresh forages and grasses make up thebulk of the diet, a large amount of water isconsumed, which could limit intake of en-ergy and protein sources.Although minerals are not digested by ani-mals, some are essential to their health. Inorder to determine the individual mineralcontent, such as calcium and phosphorus, youmust order mineral analysis of the sample(usually includes all macrominerals andsome microminerals).CP includes both true protein and non-pro-tein nitrogen (which can be used most effec-tively by ruminant animals). Because feedshigh in protein are generally more expensive,compare feed costs on the basis of cost perpound of CP rather than per pound of DM.For swine, poultry and other monogastrics,knowing the amount of each essential aminoacid in the feed is critical. Some protein frac-tions are more digestible than others, but ingeneral the higher the protein level, the moredigestible is the feed. Laboratories can ana-lyze for amino acids (lysine, methionine, etc.)and protein fractions (soluble, insoluble).Because fat has 2.25 times more energy perunit of weight compared to carbohydrates,feeds with high fat content are more energy-dense and are added to diets to increase calo-ries, provide essential fatty acids, and (insome cases) improve palatability. Fat is alsohelpful in lubricating and maintaining feedmixing equipment.CF analysis has been replaced by NDF andADF analysis for ruminant feedstuffs, but itis still used by the feed industry as a mea-sure of fiber content for monogastrics.NDF, or total fiber, influences level of in-take. High levels will limit intake, but mini-mum levels are necessary to prevent fatten-ing during pregnancy, and also to maintain ahealthy rumen in ruminants. It is the fiber inthe diet that stimulates rumination, chewing,and saliva production.ADF, or the least digestible portion of fiber,affects a feed’s digestibility - the lower theADF content, the higher the digestibility. Itis used in calculating energy estimates, suchas TDN (total digestible nutrients) or NE (netenergy).Cellulose is digested well by ruminants,moderately by horses and rabbits, and poorlyby swine and poultry.Lignin has no known nutritive value, exceptas a bulk factor. At high levels, it reducesdigestibility of other nutrients in a ration.The NFE fraction in grain can be readilyutilized as a nutrient by nearly all livestockspecies, but in forages and roughage it isless available to the animal.

Livestock Feed Analysis: How To Interpret the Results

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Livestock Feed Analysis: How To Interpret the Results

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