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Understanding quality

Don Ball Mike Collins Garry Lacefield Neal Martin David Mertens Ken Olson Dan Putnam Dan Undersander Mike Wolf

Contents Understanding forage quality 1 What is forage quality? 2 Factors affecting forage quality 3 Species differences 3 Temperature 3 Maturity stage 4 Leaf-to-stem ratio 4 Grass- mixtures 5 Fertilization 5 Daily fluctuations in forage quality 5 Variety effects 5 Harvesting and storage effects 6 Sensory evaluation of 7 Laboratory analysis of forage 8 Laboratory analytical techniques 8 Laboratory proficiency 10 Understanding laboratory reports 11 Matching forage quality to animal needs 12 Reproduction 12 Growth 13 Fattening 13 Lactation 13 Economic impacts of forage quality 14 forage quality 14 Hay quality 15 Other considerations 15 Key concepts to remember 15 Additional information 15 Glossary 16 Adequate animal nutrition is essential In recent years, advances in plant and Understanding for high rates of gain, ample milk pro- animal breeding, introduction of new duction, efficient reproduction, and products, and development of new forage quality adequate profits (see sidebar). management approaches have made orage quality is defined in various However, forage quality varies greatly it possible to increase animal perform- ways but is often poorly under- among and within forage crops, and ance. However, for this to be realized, Fstood. It represents a simple nutritional needs vary among and there must be additional focus on concept, yet encompasses much com- within animal species and classes. forage quality.The purpose of this plexity.Though important, forage Producing suitable quality forage for a publication is to provide information quality often receives far less consid- given situation requires knowing the about forage quality and forage eration than it deserves. factors that affect forage quality, then testing that can be used to increase exercising management accordingly. animal performance and producer Analyzing for nutrient content profits. can be used to determine whether quality is adequate and to guide proper ration supplementation.

IMPORTANCE OF FORAGE QUALITY Forage quality has a direct effect on animal performance, forage value, and, ultimately, on profits.The following graphs show the links between quality, performance, and returns. Weight gain Milk production Reproductive efficiency Stocker beef gains from different Production from 8 tons/acre of Conception rates of cows fescue forages, Alabama hay of either low or high quality, Wisconsin or fescue/, Indiana & Illinois -infected 15,000 100 ) increase = $400 profit Indiana tall fescue e r

c Illinois )

a 12,000 80

hybrid - / % ( b l e sudangrass ( t n 9,000 a r 60 o

sericea i t n c lespedeza o i u t d

6,000 p 40

orchardgrass o e r c p

& white clover n k o l c annual i 3,000 20 m

ryegrass m 0 0 alfalfa low-quality high-quality tall fescue clover & tall fescue hay hay 0.0 0.5 1.0 1.5 2.0 2.5 average daily gain (lb)

Hay sale prices Prices paid in quality-tested hay auctions, Effect of forage quality on hay price Wisconsin, 1984-98 average all California markets (1996-2000) 160 160 ) n

o 140

140 t / ) $

( 120 n 120 o d i t /

a 100

$ 100 p ( e d 80 i c

80 i a r p p 60 e

60 e

c supreme (<27% ADF) i g r a 40 premium (27-30% ADF) r p 40 e

v 20 good (30-32% ADF) 20 a fair (32-35% ADF) 0 0 <7575-86 87-102 103-124 125-150 >150 15234 year forage quality (RFV)

1

UNDERSTANDING FORAGE QUALITY

analyses, forage yield and nutrient animal sensitivity. High-quality What is forage content are usually expressed on a forages must not contain harmful dry matter (DM) basis. Forage dry levels of anti-quality components. quality? matter can be divided into two ■ Animal performance is the orage quality can be defined as the main categories: (1) cell contents ultimate test of forage quality, extent to which a forage has the (the non-structural parts of the especially when forages are fed Fpotential to produce a desired plant tissue such as protein, sugar, alone and free choice. Forage animal response. Factors that influence and starch); and (2) structural com- quality encompasses “nutritive forage quality include the following. ponents of the cell wall (, value” (the potential for supplying hemicellulose, and lignin). ■ Palatability Will the animals eat nutrients, i.e., digestibility and the forage? Animals select one ■ Anti-quality factors Various com- nutrient content), how much forage over another based on pounds may be present in forage animals will consume, and any smell, feel, and taste. Palatability that can lower animal perform- anti-quality factors present. Animal may therefore be influenced by ance, cause sickness, or even result performance can be influenced by texture, leafiness, fertilization, dung in death. Such compounds include any of several factors associated or urine patches, moisture content, tannins, nitrates, alkaloids, cyano- with either the plants or the pest infestation, or compounds glycosides, estrogens, and myco- animals (figure 1). Failure to give that cause a forage to taste sweet, toxins.The presence and/or proper consideration to any of sour, or salty. High-quality forages severity of these elements depend these factors may reduce an are generally highly palatable. on the plant species present animal’s performance level, which (including weeds), time of year, in turn reduces potential income. ■ Intake How much will they eat? environmental conditions, and Animals must consume adequate quantities of forage to perform well.Typically, the higher the Figure 1. Factors that affect animal performance on forage. palatability and forage quality, the higher the intake. Animal performance ■ Digestibility How much of the Nutrients utilized per unit of time forage will be digested? Digestibility (true feeding value) (the extent to which forage is absorbed as it passes through an animal’s digestive tract) varies greatly. Immature, leafy plant Plant/animal complex ■ tissues may be 80 to 90% digested, Balance of nutrients relative to need ■ while less than 50% of mature, Extent of of nutrients ■ stemmy material is digested. Rate of digestion of nutrients ■ Effective utilization of digested nutrients ■ Nutrient content Once digested, ■ Availability and palatability of forage will the forage provide an adequate ■ Level of intake level of nutrients? Living forage ■ Response to anti-quality factors plants usually contain 70 to 90% ■ Interaction with supplements water.To standardize

Potential forage Potential animal feeding value performance

Potential Anti-quality Potential Genetic Environmental nutritive value factors intake factors factors Genotype Genotype Climate Plant part Soil Body size Physiological Pests Maturation Pests Sex factors Herd effects

Age Source: Marten, G.C., D.R. Buxton, and R.F.Barnes, 1988. Feeding value (forage Body condition quality). In Alfalfa and Alfalfa Improvement, Monograph no. 29. Madison,Wis.: Health ASSA/CSSA/SSSA. 2 A comparison of and alfalfa Cool-season species are generally Factors affecting from the second cut of a mixed stand higher in quality than warm-season (figure 2) illustrates typical species dif- grasses.The digestibility of cool- forage quality ferences in quality. Alfalfa, at early season grass species averages about any factors influence forage bloom, had 16% crude protein (CP) 9% higher than warm-season grasses. quality.The most important are compared with 9.5% in timothy. Minimum crude protein levels found Mforage species, stage of maturity However, applying substantial amounts in warm-season grasses are also lower at , and (for stored forages) of nitrogen fertilizer to grasses can than those found in cool-season harvesting and storage methods. make their CP levels comparable to grasses.Within each category, annual Secondary factors include soil fertility legume forage. grasses are often higher in quality and fertilization, temperatures during In the same comparison, timothy had than perennials. Due to differences in forage growth, and variety. considerably higher levels of neutral leaf anatomy (tissue arrangement or detergent fiber (NDF) than alfalfa. structure), warm-season grasses Species differences Typically, higher NDF (total fiber) levels convert sunlight into forage more effi- and a slower rate of fiber (cell wall) ciently than cool-season grasses, but vs. grasses digestion for grass forages results in their leaves contain a higher propor- Legumes generally produce higher lower voluntary intake compared with tion of highly lignified, less digestible quality forage than grasses.This is legumes. Faster digestion allows more tissues. because legumes usually have less forage (and thus more nutrients) to be fiber and favor higher intake than consumed. Temperature grasses. One of the most significant Cool-season vs. Plants grown at high temperatures benefits of growing legumes with generally produce lower quality grasses is improvement of forage warm-season grasses forage than plants grown under quality. There is considerable variation in cooler temperatures, and cool-season forage quality among the grasses species grow most during the cooler used as cultivated forages in the months of the year. However, forage of United States. Forage grasses are any species tends to be lower in divided into two broad categories: quality if produced in a warm region cool season (adapted to temperate rather than a cool region. For example, regions) and warm season (best in one study annual ryegrass grown at adapted to tropical or subtropical temperatures of 50° to 59°F produced environments). Cool-season grasses forage made up of 59% leaf material, include orchardgrass, Kentucky blue- but only 36% leaf matter when grown grass, perennial and annual ryegrass, at 68° to 77°F. and tall fescue. Bermudagrass, bahia- grass, dallisgrass, and corn are examples of warm-season grasses.

Figure 2. Forage quality of alfalfa and timothy components of a mixture.

70 alfalfa

) 60 timothy % (

r 50 o t c a f 40 y t i l a

u 30 q e

g 20 a r o f 10

0 crude NDF ADF cell wall cell wall protein digestibility digestion rate/hour Source: Collins, M. 1988. Composition and fibre digestion in morphological components of an alfalfa–timothy sward. Anim. Feed Sci.Tech. 19:135–143. 3 UNDERSTANDING FORAGE QUALITY Table 1. Effect of plant maturity on intake and digestibility of Maturity stage cool-season grass hays by lactating cows (summary of several studies involving various grasses). Maturity stage at harvest is the most important factor determining forage relative quality of a given species (table 1 and cutting growth hay intake hay digestible date stage per day digestibility DM intake figure 3). Forage quality declines with advancing maturity. For example, cool- % body weight/day ———— % ———— June 3–4 vegetative 2.64 63.1 166 season grasses often have dry matter June 11–12 early boot 2.36 65.7 154 (DM) digestibilities above 80% during June 14–15 late boot 2.45 62.6 153 the first 2 to 3 weeks after growth ini- June 16–18 early head 2.28 58.5 133 tiation in spring.Thereafter, digestibil- July 1 bloom 2.30 52.7 121 ity declines by 1⁄3 to 1⁄2 percentage July 5 bloom 2.13 52.2 111 July 7–8 bloom 2.05 52.2 107 units per day until it reaches a level July 9–10 late bloom 1.95 51.5 100 below 50%. Source: Stone, J.B., G.W.Trimberger, C.R. Henderson, J.T. Reid, K.L.Turk, and J.K. Loosli. 1960. Maturity at harvest also influences Forage intake and efficiency of feed utilization in dairy cattle. J. Dairy Sci. 43:1275–1281. forage consumption by animals. As plants mature and become more fibrous, forage intake drops dramati- Table 2. Leaf and stem quality of alfalfa and timothy components of cally.Typical DM digestibility and intake a mixture. values for cool-season grass hays har- plant % of the vested at different stages of maturity component whole plant CP NDF ADF are shown in table 1. Numerous studies Alfalfa ——————————— % ——————————— have shown similar effects in many dif- upper leafa 30.7 23.9 27.7 18.5 ferent species. lower leaf 12.8 21.8 25.9 16.6 Intake potential decreases and NDF upper stema 6.5 13.4 52.6 38.6 lower stem 50.0 9.6 67.8 52.9 concentration increases as plants age. Timothy This is because NDF is more difficult to leaf 29.6 18.3 49.1 25.5 digest than the non-fiber components stem 70.4 5.8 72.5 42.6 of forage. Also, the rate at which fiber aUpper leaf and stem were taken from the last five internodes on each stem. is digested slows as plants mature. Source: Collins, M. 1988. Composition and fibre digestion in morphological Therefore, digestion slows dramati- components of an alfalfa-timothy sward. Anim. Feed Sci.Tech. 19:135–143. cally as forage becomes more mature. Leaf-to-stem ratio Figure 3. Effect of plant maturity on forage intake and digestibility. Reduced leaf-to-stem ratio is a major cause of the decline in forage quality with maturity, and also the loss in high crude protein stems quality that occurs under adverse hay fiber curing conditions. Leaves are higher in leaves y t

i quality than stems, and the proportion l a

u of leaves in forage declines as the

q minerals e plant matures. v medium i t a l The variation in quality of leaves and e r stems is illustrated in table 2.The oldest portion of alfalfa stems had less than 10% CP compared with 24% in low alfalfa leaves. Stems of both species grasses leafy boot heading bloom had much higher fiber levels than legumes leafy prebud bud bloom leaves, but the older, lower alfalfa growth stage leaves were similar in quality to the Source: Adapted from Blaser, R., R.C. Hammes, Jr., J.P.Fontenot, H.T. Bryant, C.E. Polan, upper, younger leaves. However, older D.D.Wolf, F.S.McClaugherty, R.G. Klein, and J.S. Moore. 1986. Forage–animal alfalfa stem tissue was considerably management systems.Virginia Polytechnic Institute, Bulletin 86-7. lower in quality than young stem tissue. 4 Reproductive growth lowers Fertilization Daily fluctuations in leaf-to-stem ratio, and thus forage quality. Most cool-season grasses Fertilization of grasses with nitrogen forage quality (N) often substantially increases yield require a period of cool temperatures As early as the 1940s, changes in (vernalization) for flowering, so they and also generally increases CP levels in the forage. In one study, fertilizing soluble carbohydrate levels in alfalfa produce reproductive stems only in were linked to time of day. Plants accu- the spring.Thus, the forage quality of switchgrass with 70 pounds/acre of nitrogen raised CP from 5.3 to 6.4%, mulate soluble carbohydrates during regrowth of these grasses is greater daylight and then use them overnight. and changes less over time because and increased voluntary intake by 11%. (Fertilizing alfalfa and other Thus, soluble sugars are lowest in the they have higher leaf-to-stem ratios morning and highest after a day of than first-growth forage. Legumes and legumes with nitrogen to improve quality is not recommended.) bright sunshine. Recent studies in low some grasses such as bermudagrass rainfall have shown higher can flower several times each season, Fertilization usually has little or no effect on digestibility. Fertilization forage quality when alfalfa is harvested so their forage quality patterns are in the late afternoon rather than in the less closely linked to season. with phosphorus (P), potassium (K), or other nutrients that increase yield may morning. It appears that the advantage actually slightly reduce forage quality of afternoon harvest is greatest on Grass–legume mixtures when growth is rapid. Excessive levels cool, sunny days and when the forage Grass–legume mixtures generally have of some elements such as potassium is highly conditioned to increase drying higher crude protein concentration may in some cases decrease the avail- rates and minimize respiration in the and lower fiber concentration than ability of other elements such as mag- windrow. However, afternoon pure grass stands. In Georgia, mixtures nesium (Mg) in the diet. may not be advisable in high rainfall of seven legumes with bermudagrass areas where every hour of good drying (receiving no nitrogen fertilizer) ranged time is needed in curing hay. from 11 to 13% CP compared with only 11% CP in pure bermudagrass receiv- Variety effects ing 90 pounds/acre of nitrogen There are many examples of plant annually. In another study, first-cutting breeding improving forage quality. alfalfa containing The variety ‘Coastcross-1’ bermuda- about 30% grass is about 12% higher in timothy had a CP digestibility than ‘Coastal’ bermuda- level of 17.5% grass, supporting 30% higher average compared with daily gains by beef steers. In species 20.5% in alfalfa such as timothy that have a wide with no grass. range of maturity dates, later- maturing varieties tend to be slightly lower in digestibility because early types make more of their growth under lower temperatures. Some corn varieties have higher content and/or digestibility than others. The development of multifoliate alfalfa varieties (having more than three leaflets per leaf) is a strategy aimed at increasing forage quality, but some multifoliate varieties have no higher leaf percentage than tradi- tional trifoliate varieties. Some trifoli- ate varieties exhibit superior quality, but care should be taken to assure that a “high-quality” variety is not sub- stantially lower in yield.

5

UNDERSTANDING FORAGE QUALITY Harvesting and Rainfall during curing damages Quality losses also occur due to legume leaves most. For alfalfa hay weathering, plant respiration, and storage effects exposed to both drying and leaching microbial activity during storage. In Leaf shatter, plant respiration, and losses, more than 60% of the total high rainfall areas, losses can be large leaching by rainfall during field drying losses of dry matter, CP,ash, and for round bales stored outside, due to of hay can significantly reduce forage digestible DM were associated with weathering of the outer layers. In an quality, particularly with legumes. the leaves. Rain during field drying has Indiana study, digestibility and crude Figure 4 illustrates typical effects of less impact on the forage quality of protein content of the unweathered rainfall during the drying process. grasses than legumes. In one study, center portions of round bales of Moderate rain damage reduced alfalfa alfalfa hay that received rain was 12 mixed grass hay stored outside for 5 CP levels slightly and digestibility dra- percentage units less digestible than months was 59% and 13.5%, respec- matically, but NDF and ADF levels fresh forage, compared with a differ- tively, while the weathered outer increased sharply. Red clover hay ence of only 6 percentage units for portions of bales had a digestibility of quality was also greatly reduced by grass hay produced under similar con- 43%, and a crude protein content of rain, even though crude protein ditions. Damage from rain increases as 16.4%. In the same study, the increased.The total amount of crude forage becomes dryer, and is espe- digestibility and crude protein content protein did not increase; the percent- cially severe when rain occurs after it of unweathered centers of alfalfa/ age of crude protein in the remaining is ready to bale. grass bales were 57% and 14.3%, dry matter was higher due to leaching respectively, and 34% and 16.9% for of highly soluble constituents. the weathered outer portions of bales, However, leaching also increases the respectively. proportion of unavailable ADIN (see In a study in Louisiana (figure 5), baled glossary) in the hay. ryegrass stored outdoors on the ground lost 40% of the initial DM during 1 year of storage. Protected Figure 4. Change in forage quality of alfalfa and red clover hays exposed to bales lost an average of 10% of the rain during curing. initial DM during the same period. Alfalfa Red clover Refusal during feeding to mature cows ranged from only 1% for inside-stored 80 80 no rain no rain bales to 22% for bales stored outside 70 1.6 inches rain 70 1.6 inches rain on the ground. ) 2.4 inches rain 2.4 inches rain %

( 60 60 r o t c

a 50 50 f Figure 5. Changes during storage of y t i l 40 40 ryegrass round bales in Louisiana. a u q

e 30 30 g 40 a r o 20 20 on ground, no cover f 35 rack with cover 10 10 inside 30 0 0 crude NDF ADF digestibility crude NDF ADF digestibility 25

protein protein ) % ( 20 s Source: Collins, M. 1983.Wetting and maturity effects on the yield and quality of legume hay. s o Agron. J. 75:523-527. l 15

10

5

0 dry matter loss feed refusal*

*Refusal measurements were made after 7 months of storage. Source: Verma, L., and B.D. Nelson. 1983. Changes in round bales during storage.Trans. ASAE. 26:328-332.

6

Some storage and feeding losses are The maturity of the hay, one of the Color helps sell hay to the average inevitable. Estimated losses from har- main factors determining forage buyer. Color alone is not a good indi- vested forage stored at various quality, can be visually assessed.The cator of forage quality, but it can be an moisture contents are provided in number and maturity of seed heads indicator of harvest and storage con- figure 6. and blooms, and the stiffness and ditions. A bright green color suggests fibrousness of the stems are indicators that hay was cured quickly and pro- of plant maturity. tected during storage. Slow curing Sensory Leafiness is particularly important; prolongs plant respiration, which the higher the leaf content, the higher reduces forage quality. Hay that is rain evaluation of hay the forage quality. Leafiness can be damaged after being partially dried uch can be learned from a affected by plant species, by stage of will lose color due to leaching. Mold careful sensory examination of maturity at harvest, and (especially in growth on leaves and stems or Mhay. First, the plant species legume hays) by handling that results exposure to sunlight will also bleach present can be determined. Does the in leaf loss. hay. Baling at moisture contents at or hay consist almost exclusively of a par- above 20 to 25% may cause high bale Texture is a consideration. Softness temperatures that result in tan to ticular forage crop? Does the forage usually results from early cutting, high crop tend to be higher in quality than brown or black colors (commonly leaf content, and a suitable moisture called “tobacco hay”). other forages? Does the hay contain level at baling.When hay is “very soft” weeds? If so, what percentage is and pliable, it is difficult to distinguish A pleasant odor indicates hay was weeds and how much nutritional between stems and leaves just by cured properly. Moldy, musty odors benefit do they provide to ? feeling the hay.“Soft” hay is soft to the may occur in hay stored at moisture Could they be toxic? touch, but stems can be detected contents above 16 to 18% (above 14% easily.“Slightly harsh” hay has stems for 1-ton square bales). Animals may that are a little rough.“Harsh or brittle” respond to off-odors by going off hay is dry, stemmy, and unpleasant to feed. Odors caused by heating the touch.“Extremely harsh” hay can (>125°F) result from hay being baled injure an animal’s mouth, lowering at too high a moisture content or from intake. ensiling forage that is too dry. Interestingly, hay with a slightly caramelized odor is often quite palat- able to livestock, even though the quality is reduced. (The odor of silage Figure 6. Estimated dry matter loss during harvest and storage can indicate good or bad fermenta- of hay-crop forages at various moisture levels. tion; if it smells of butyric acid— similar to rancid butter—it may lack 50 palatability, and low animal intake is harvest loss likely.) storage loss Dusty hay is usually the result of soil 40 -dried field-cured being thrown into the hay by hay hay ) teeth hitting the soil.The presence or % direct-cut wilted (

s absence of molds, dust, and odor are s 30 silage silage haylage o l

r referred to as organoleptic qualities. e t

t moisture

a Visual inspection can also detect range for m 20

y concrete foreign matter (anything that has little r d tower or no feed value).Tools, sticks, rocks, 10 wire, items of clothing, dead animals, and cow chips have all been found in hay and are obviously undesirable. 0 Dead animals in hay can cause 80 70 60 50 40 30 20 10 botulism, a deadly disease that can kill moisture at harvest (%) animals.

Source: Michigan State University

7

UNDERSTANDING FORAGE QUALITY

(and thus low palatability) or excessive HOW TO PROPERLY Laboratory leaf loss (linked with lowered forage quality), while high moisture (greater SAMPLE HAY analysis of forage than 14 to 18%) indicates a risk of Use a good probe—The hay probe ccurate laboratory testing of feed mold. For silage, excessively low should have an internal diameter of at and forage is required to provide moisture (below 45%) can indicate 5 least ⁄8 inch.The cutting edge should Athe information needed to formu- heat damage, while high moisture be at right angles to the shaft, and late animal rations.Testing to assess (above 70%) can indicate poor fermen- kept sharp. Dull probes will not obtain quality also provides a basis for com- tation and potential intake problems. a representative sample. Core mercial hay sales. Detergent fiber analysis—Acid samplers that cut through a cross- detergent fiber (ADF) and neutral section of a bale provide the best rep- A forage analysis should reflect the detergent fiber (NDF) are frequently resentation of stems and leaves. Avoid average quality of the material being used as standard forage testing tech- using open augers as they selectively tested. Only a few grams of material niques for fiber analysis. NDF approxi- sample leaves. represent tons of forage, so it is essen- tial to obtain a representative sample. mates the total cell wall constituents Sample at random—It is important Therefore, sampling technique is including hemicellulose, whereas ADF to select bales at random from extremely important (see sidebars on primarily represents cellulose and throughout the hay “lot” (defined in how to properly sample hay, silage, lignin. ADF is often used to calculate sidebar on page 10). Avoiding some and pasture forage). digestibility, and NDF is used to bales and choosing others based on predict intake potential. As fiber appearance will bias the sample. For increases, forage quality declines. stacked hay, samples should be taken Laboratory Protein—Protein is a key nutrient that from bales at various heights in the analytical techniques must be considered both in amount stack. Laboratory analyses are used to deter- and type for various animal diets. It is Take enough core subsamples— mine the nutritive value of forages. A commonly measured as crude protein Taking at least 20 core samples from a typical forage analysis includes meas- (CP), which is 6.25 times the nitrogen hay lot minimizes sample variation. urements of dry matter, crude protein, content of forage. Crude protein is used Use the proper technique—For rec- and fiber (acid detergent fiber and because rumen microbes can convert tangular bales of all sizes, insert the neutral detergent fiber). Sometimes non-protein nitrogen to microbial hay probe 12 to 18 inches deep at a ash is measured, and when heat- protein, which can then be used by the right angle into the center of the ends damaged protein is suspected, acid animal. However, this value should be of bales. For round bales, the probe detergent insoluble crude protein used with some care, as it is not appli- should be inserted at right angles to should be measured. Many other cable to non- or when high the outside circumference of the results provided on laboratory reports levels of nitrate are present in the bales. (digestible energy or protein, net forage. Handle samples correctly—Combine energy, total digestible nutrients, High-performing animals, especially core samples from a given lot into a potential intake, etc.) are calculated or milking dairy cows, need larger single sample and store in a sealed estimated from measured analyses. amounts of protein to be absorbed plastic freezer bag. Samples should be See figure 11 on page 17. from the intestines than rumen protected from heat or direct sun, and Dry matter—Dry matter (DM) is the microbes produce.Therefore, they need promptly sent to a laboratory for portion (weight) of forage other than a certain amount of bypass protein (or analysis. The sample should weigh water. Nutrients are typically reported RUP) in the ration. Recently, calibrations approximately 1⁄2 to 3⁄4 pound.With on a DM basis to eliminate the dilution have been developed that allow RUP in larger samples, many labs will not effect of moisture and to allow more forages to be estimated using near grind the entire sample.Too small a direct comparison of feeds and easier infrared reflectance spectroscopy. sample will not adequately represent formulation of diets.To compare prices Acid detergent insoluble crude the hay lot. and nutritive value among lots of protein (ADICP)—This estimates the Split samples correctly—To test the forage, they should be adjusted to a nitrogen that has low digestibility in performance of a particular laboratory DM basis. Sometimes hay is compared the rumen and the intestine. It is (or the sampling technique), a fully or sold on a 90% DM basis, which important for determining the value ground and thoroughly mixed sample closely resembles the average DM of of heat-damaged hay and silage. A should be split and submitted. air dried feeds. little ADIN is good because it increases Unground samples should not be split. For hay, excessively low moisture (less bypass protein, but too much may than 10%) could indicate brittleness reduce total protein availability. 8

Digestible energy estimates— Energy values can be determined HOW TO PROPERLY SAMPLE SILAGE directly only by feeding trials. Sampling during harvesting Laboratory reports provide calculated Collect three to five handfuls of chopped forage from the middle of a load values.There are four basic during unloading, place in a plastic bag, and refrigerate immediately. Follow approaches: the same procedure for several loads. Combine samples from a single har- A. The most common has been to vested field and mix well. Place the entire sample in a clean plastic bag or measure a single fiber fraction other container, and seal tightly. Label each container with your name and (usually ADF) and use it to calcu- address as well as the date, sample number, and forage type. Store the late an estimated digestibility, sample in a cool place (do not freeze) until you send it to a laboratory for total digestible nutrients (TDN) or analysis. Repeat for each field, variety, or hybrid. If filling tower silos or net energy for lactation (NEl). tubes, keep a record of where each lot is in the silo or tube. Feeding colored B. Summative equations are predic- plastic strips through the blower at the end of each lot may help identify the tions of TDN or NEl from multiple lots later. measures of forage composition. Silos with seepage should be resampled upon feeding because loss of These measures often include soluble compounds due to seepage will increase dry matter, acid detergent NDF,NDF nitrogen, crude protein, fiber and neutral detergent fiber, and decrease crude protein. Resample silos ether extract, lignin, and neutral at feeding that were filled with forage at less than 50% moisture that may detergent fiber nitrogen.These have heated excessively, causing increased acid detergent fiber and acid predictions are more accurate detergent fiber insoluble nitrogen. Recheck dry matter of at feed out. than those of single fiber fractions, Fiber and protein are not likely to change much during storage, except as but are much more time consum- mentioned above, but moisture can change significantly. ing and expensive. Beware of labo- Ensiled material from a tower silo ratories that output “summative Do not sample the spoiled material on the top or bottom of the silo; wait equations” but don’t measure all until 2 to 3 feet of silage have been removed. Collect a 1 to 2 pound sample components. from the silo unloader while it is operating. Collect samples from opposite C. Some scientists have begun sides of the silo. Combine the samples and mix well. Place the entire sample looking for additional factors to in a plastic bag and handle as discussed above. better describe the energy content of forage.The most Ensiled material from a bunker silo common additional measure at If feeding with a TMR (total mixed ration) mixer—Load silage from bunker present is to determine nonfibrous into TMR mixer and mix well.Take several grab samples to collect a 1 to 2 carbohydrate (NFC) or starch pound total sample. Place in a plastic bag and handle as discussed above. content. If not feeding with a TMR mixer—Collect a 1 to 2 pound total sample from D. In vitro and in situ digestibility are the different vertical layers of the silo face. Grab several handfuls from freshly generally considered the best exposed forage after the day’s feeding has been removed. Do not sample the analyses to use to predict animal spoiled material on top of the silo. Combine handfuls and mix well. Place the performance. Both use rumen fluid entire sample in a clean plastic bag or other container, and seal tightly. Store to digest the samples either in a immediately in a cold place until shipping. Label each container as indicated beaker or test tube (in vitro) or in a earlier. Place in a plastic bag and handle as discussed above. porous bag placed in the rumen via a fistula or port in the animal’s side (in situ). In 2001, the National Research Council recommended measuring digestible fiber (dNDF) and then calculating total digestible nutrients (TDN) as a much better estimate of energy content of the forage than acid deter- gent fiber. Digestible NDF can be esti- mated two ways: by measuring lignin or by measuring in vitro digestion. As shown in figure 7, the two methods give different results. It is believed 9 UNDERSTANDING FORAGE QUALITY that measuring dNDF by in vitro diges- nondigestible fibrous portion of the Laboratory proficiency tion is much more indicative of animal plant which is most of the cell wall performance than measuring it by material (figure 8). As the NDF level The accuracy of forage analysis lignin analysis. increases, voluntary feed intake tends depends on the analytical procedures used and the precision of laboratory Intake estimates—Voluntary intake, a to decline. However, if NDF of the techniques.The National Forage Testing prime consideration in feeding, is ration is too low, health problems such Association (NFTA) certifies the profi- often estimated based on neutral as acidosis, displaced abomasums, and ciency of laboratories with regard to detergent fiber (NDF) content. NDF foundering may occur. accurately testing hay and corn silage consists of the slowly digested and for DM, CP,ADF,and NDF.It is advisable to use a NFTA certified laboratory. For a current listing of certified laborato- Figure 7. Comparison of TDN calculated from lignin and in vitro digestion for ries, as well as more information about alfalfa and grasses. (The diagonal line indicates values for identical results.) proficiency testing, visit NFTA’s web site (www.foragetesting.org). 70 When evaluating a forage test report, 65 keep in mind that none of the values, either measured or calculated are om 60 absolute.There is variability in hay 55 stacks or silage, and some variation ed fr t 50 associated with lab analysis. Normal digestion

o lab variation, not including errors

alcula 45 associated with poor sampling of

in vitr 40 forages, are considered to be: CP TDN c 35 (+/-0.5), NDF (+/-0.9), and ADF (+/-0.7). 30 For example, a reported value of 20% 40 45 50 55 60 65 70 CP should be considered to be anywhere between 19.5 and 20.5% TDN calculated from lignin under normal circumstances. Relative feed value (see glossary) will vary IDENTIFICATION within 8 points. OF A FORAGE LOT A lot is defined as forage taken Figure 8. Structural components of alfalfa. from the same farm, field, and cut under uniform conditions within a 48-hour time period. A lot can rep- resent several truck or loads, but all the forage should leaves: 18-28% NDF Non-structural have been harvested and stored 12-20% ADF carbohydrates (NSC) 22-35% CP under identical conditions. For (sugars & starch) accurate test results, hay or silage 25-35% stems: 35-70% NDF Structural should be stored by lots, and 30-55% ADF carbohydrates separate samples taken from each 10-20% CP (NDF: cellulose, lot. Any special conditions that hemicellulose, result in quality differences in a lot, cell contents (NSC) & lignin; 30-50% such as rain damage during harvest 100% digestible ADF: cellulose & lignin) Proteins or excessive weed populations, (soluble & bound) should be noted to allow later Plant 15-25% cell 2-3% Fats (lipids) assessment of the reasons for 8-13% Ash (minerals) quality variations. cell wall (NDF) Whole plant20-60% digestible Whole plant analysis

Source: Adapted from Putnam, Dan, 2000. Producing high quality alfalfa: Factors that influ- ence alfalfa forage quality. Proc. CA Plant and Soil Conference, Jan. 19-20. Stockton, CA. 10 Understanding laboratory reports Various labs present analysis results in different ways, but the following items should be included. Laboratory identification Should include contact infor- mation (address, fax, phone).

Lab certification ort This seal indicates the sis rep Feed analy oratory lab has passed the nalysis Lab ABC Feed A e Street NFTA proficiency test. Anywher y, ST 00000 Any Cit ax: 000-000-0000 om 000-000-0000 F www.ABC.c Feed description The Phone: .com Web: A-1-720 ABCLabs@IP tification: lfalfa client needs to provide Client identification Email: Feed iden A t ype: Doe farm accurate and detailed Helps ensure infor- Joe Clien Feed t igin: street er or feed or South 720 information about the t name: 123 Any Grow mation is reported Clien AS 12345 cation: First, 05/25/01 forage or feed to aid in ess: Anytown, Field lo vest date: to correct person Addr Wilted for silage interpretation. , State, Zip 123-456-7890 Cutting and har or organization. City om eservation: John Doe [email protected] Feed pr Phone: : 05/25/01 Sampler en: Email: 05/26/01 05/29/01 Date sample tak ed: ed: te sample shipp 05/28/01 e sample analyz 05/31/01 Da eived: Dat orted: ec esults rep 00-000123 Date sample r . Date r ode: om 12 loads tification c terial fr Lab iden de: 4567 ed ma ondition. Sample ession co t in good c Invoice/acc Grab samples of chopp te amoun 90% DM identity and d and handling: terial of adequa 100% DM ample metho Chopped ma ed description Report S eceived: As receiv ondition as r 10.0 Sample c Method should list lot iden- 0.0 90.0 65.0 tification number, , units 100.0 21.6 Nutrients tions 35.0 sampling date, ermina In-house 105-16 24.0 26.1 Analytical det 8.4 sample method e, % In-house 105-16 29.0 34.2 Oven moistur % C 990.03 10.2 y matter, AOA 38.0 and handling, and Oven dr ook 379 13.3 otein, % Handb 10.8 condition of the Crude pr , % 1993 gent fiber NFTA, 12.0 3.6 sample on arrival. Acid deter 4.2 4.0 9.0 aNDF, % 1.4 uctural Smith, 1983 10.0 Total nonstr 3.5 ates, % AOAC 920.39A carbohydr 2.07 AOAC 942.05 2.30 , % 0.30 Fat 0.81 0.33 Ash, % tion 0.12 NIR ISI equa tion Analytical results Results Minerals % NIR in-house equa 21.6 should be reported on a Calcium, us, % 24.0 54.5 100% dry matter (DM) Phosphor 8.4 ed values 60.6 0.61 basis. Additional columns Calculat , 1988 21.2 soluble Mertens 0.68 146.0 Neutral det. arble, 1989 may be included for ates, % Bath & M 0.24 162.0 carbohydr ts, % . ADF reporting results on an ien Mertens leg 56.8 Total digestible nutrtion, Mcal/lb 1993 as-is (as-received) or an gy of lacta NFTA, Net ener eed value air-dry (90% DM) basis. Relative f ts: Commen

Signature:

Comments and signature There should be an area where laboratory Calculated results There should be a personnel can indicate concerns or clear distinction between results provide other feedback about the determined analytically and those sample or results. calculated from analytical determi- nations.

11

HOW TO PROPERLY SAMPLE PASTURE FORAGE Sampling pasture forage is espe- cially challenging because the Matching Reproduction quality of pasture forage is con- Reproduction requires relatively small stantly changing. Also, selective forage quality increases in nutrient requirements. grazing by animals affects the Conception of females is often quality of their diets. to animal needs enhanced by “flushing” (increased If are rotationally energy intake during the breeding nimal performance is determined stocked, collect forage randomly season). Males also need additional by feed availability, feed nutrient from several spots so the entire energy for the increased activity content, intake, extent of diges- pasture will be represented. It may A during the breeding season.Thus, tion, and metabolism of the feed be helpful to observe how the during breeding, animals should digested, but availability and intake animals are grazing their present receive forages that are 10 to 20% most often determine animal per- pasture, then collect a sample to higher in digestible energy, and lower formance. A cow never produced milk the same stubble height from the in NDF, than those fed to animals on a or a steer never grew on feed that it next pasture. maintenance ration. During the didn’t eat! For a continuously stocked breeding season, males often lose pasture, forage should be col- With regard to the nutritive content of weight that must be recovered later. forage, digestible energy (digestibility) lected from several locations. Note The fetus and uterine tissues require is the most common limiting factor. whether animals are spot grazing little energy, protein, or minerals However, there are times when and try to sample what they are during the first two-thirds of preg- protein and minerals are the nutrients eating.The pasture can be nancy.Therefore, early pregnancy that limit animal performance, espe- sampled monthly or as needed. (gestation) is a time when nutritional cially in grazing situations when sup- requirements of animals are low. Mix the collected forage, then fill plementation is impractical. the sample bag. If not mailed During the last third of pregnancy, The amounts of digestible energy, immediately, refrigerate or air dry. nutrient requirements increase because protein, vitamins, and minerals fetal weight increases rapidly. Also, needed for maintenance is low females typically need to store fat relative to other animal processes. In during pregnancy that will be used to general, forages that contain less than meet the high-energy demand of early 70% NDF and more than 8% crude lactation. Not only do nutrient require- protein will contain enough digestible ments increase, the internal body space protein and energy, vitamins, and for the digestive tract is greatly reduced minerals to maintain older animals. during the latter stages of pregnancy. Thus, even many low quality forages Thus, in the last 10% of pregnancy it is and crop residues can meet the main- important to increase dietary nutrition tenance needs of some classes of substantially (<50% NDF and at least 10 animals, if protein and minerals are to 12% crude protein). adequate.

12 Growth The bodies of very young animals are rapidly developing muscle and bone. Muscle is primarily protein, and bone is mostly minerals (calcium and phos- phorus), so growing animals have much higher requirements for crude protein and minerals than older animals. Extra energy is also needed for the development of both muscle and Lactating dairy animals require a bone, but younger animals have less Fattening delicate balance of fiber: too much internal body capacity to accommo- Body fat becomes the major compo- fiber lowers energy density and limits date consumption of bulky forage nent of weight gain as an animal intake, resulting in low milk produc- than older animals. Higher require- matures, because the development of tion; too little fiber reduces produc- ments and less capacity result in the muscle and skeleton greatly dimin- tion of fat-corrected milk, increases need for greater nutrient density in ishes. Fat is a concentrated source of fattening of the female, and increases the diets of young, growing animals, energy; therefore, the fattening of incidence of digestive and metabolic especially until they reach about 50% animals requires a diet that is dense in disorders.To maximize forage use in of their mature weight. digestible energy and lower in the rations, fiber intake must be Nutrient and energy density of the protein, minerals, and vitamins. pushed to the maximum limit of the diet should be highest shortly after Fattening diets typically contain 8 to animal that will still allow it to realize birth (16 to 18% crude protein and 30 10% crude protein and less than 25% its milk production potential. Since to 40% NDF), and gradually decrease NDF, which is difficult to achieve with too much fiber intake becomes the to 12% crude protein and 55% NDF by all-forage diets because the fiber con- limiting factor in this situation, feeding the time they reach 50% of mature centration in forages limits their high quality forage is critical when weight. Milk produced by the mother digestible energy density. attempting to maximize forage intake is an excellent supplement for young by animals with high levels of milk animals that allows them to perform Lactation production. well when consuming forages. Lactation places the greatest nutrient Diets of nursing cows and at After weaning, the protein in forages demand on animals. On a dry basis, peak lactation need to contain 12 to may be too soluble and may lack the milk contains about 20 to 25% protein, 14% crude protein and less than 55% amino acid balance needed for muscle 25 to 30% fat, and high levels of NDF. However, high-producing lactat- development, or calcium and phos- minerals and vitamins to ensure the ing dairy cows, ewes, and phorus levels in forage may not be rapid growth of offspring.Whereas require diets that are 16 to 18% crude adequate.Thus, supplementing forage growth and fattening may require protein, 25 to 30% NDF,and contain diets with protein and minerals often nutrients at one and a half to two times significant levels of calcium and phos- improves the rate of growth in young the maintenance level, lactation of phorus. As in the case of fattening animals. beef cows or sheep may require nutri- animals, this is difficult to attain with ents at two to two and a half times forages alone. maintenance, and lactating dairy In most cases, the intake potential and cows, ewes, and goats may require digestible energy content of the forage nutrients at up to four to five times determines the productivity of an maintenance levels. Such high nutrient animal. However, when forage quality is demands necessitate the feeding of low and forages are the only source of high quality forages and/or feeds. nutrients, protein and minerals may limit animal performance.

13

UNDERSTANDING FORAGE QUALITY An illustration of how well various cat- Pasture forage quality egories of forage crops tend to Economic impacts provide digestible dry matter to Grazing can provide low-cost nutrition selected classes of livestock is of forage quality because livestock, rather than expen- sive machinery, harvest the forage. provided in figure 9. More detail on here is widespread recognition However, failure to make adjustments nutrient needs of animals can be that forage generally supplies a rel- to changes in pasture growth rate found in the publications of the Tatively low-cost source of nutrition during the grazing season may lead to National Research Council, available for livestock. However, the relationship either overgrazing (which reduces from National Academy Press. between forage quality and the level forage growth and may thin forage of profit realized from forage-related stands) or undergrazing (which lowers enterprises is often underappreciated. overall forage quality and increases forage waste). Consequently, grazing management can be extremely important. Figure 9. Forage digestibility ranges and their suitability for different The influence of maturity on forage classes of livestock. quality provides another reason for using pasture when feasible (figure 10). 80 The data compares the percent dry dairy cow, 50 lb milk/day matter, crude protein, and total r

e digestible nutrient of selected grasses t

t 450 lb steer, a 70 at three stages of growth: vegetative

m average daily gain 1.5 lb

y (as in a properly grazed pasture), boot

r first calf heifer d

e (when most hay should be harvested), l 60 beef cow/calf to b i

t wean 500 lb calf and mature (when much hay actually s e is harvested). For each species, forage g dry pregnant cow, i d 50 gaining condition quality was highest at the vegetative % stage.Thus, grazing not only avoids 40 mechanical harvesting costs, but also warm-season cool-season cool-season legumes often offers the advantage of higher perennial perennial annual forage quality as compared to stored grasses grasses grasses feed.

Source: Adapted from H. Lippke and M.E. Riewe. 1976. Principles of grazing management. In Grasses and Legumes in Texas (E.T. Holt, ed.) Texas Agric. Exp. Stn. Res. Monograph RM6C:169–206.

Figure 10. Forage quality dry matter (DM), crude protein (CP), and total digestible nutrients (TDN) percentages at varying growth stages.

Tall fescue Orchardgrass Bermudagrass 80 80 80 vegetative 70 boot 70 70 mature 60 60 60 ) %

( 50 50 50 t n e

u 40 40 40 t i t s

n 30 30 30 o c 20 20 20

10 10 10

0 0 0 DM CP TDN DM CP TDN DM CP TDN Source: Adapted from Kennedy, Mark, and John Jennings. 1997. Forage quality in Management Intensive Grazing in the Ozarks. Jointly published by the Top of the Ozarks and the Southwest Missouri R C & D Councils, the Missouri Department of Natural Resources, and the Natural Resources Conservation Service. 14

Hay quality Hay quality varies due to numerous factors discussed earlier in this publi- cation. Such differences should in turn be reflected in sale prices when hay is marketed.This occurred at hay auctions in Wisconsin and California (illustrated in “Importance of Forage Quality” sidebar on page 1). Other considerations Improving forage quality can result in other benefits that affect profit. Animal health, including resistance to parasites and diseases, is favored by a KEY CONCEPTS TO REMEMBER high plane of nutrition. In addition, the ■ The ultimate measure of forage ■ Fertilizing with nitrogen generally reproductive efficiency of animals is quality is animal performance. increases the crude protein level of often higher when nutritive intake is ■ Factors having the greatest impact grasses, but fertilization usually high. High quality forage also often on forage quality are forage has little or no effect on the reduces or eliminates the need for species, stage of maturity at digestible energy of forage. supplemental feeds, which usually are harvest, and (if forage is mechani- ■ Sensory evaluation of forage more expensive than non-forage cally harvested) harvesting and provides important information, sources of nutrition. storage techniques. but laboratory testing is required ■ Forage quality varies greatly to formulate rations. Additional among and within forage crops, ■ A laboratory analysis uses only a and nutritional needs vary among few grams of material to represent information and within animal classes and tons of forage.Therefore, sampling species. Knowing forage quality technique is extremely important. The following web sites contain and animal nutritional needs is information about forage quality. ■ The numbers provided on a forage necessary to formulate rations that test report are valuable but not American Forage and Grassland result in desired animal perform- absolute. Reported results vary Council: www.afgc.org ance. somewhat due to differences Forage Information System: ■ Leaves are higher in quality than within a hay lot (or other feed www.forages.orst.edu stems; young stems are higher in material sampled), sampling tech- National Forage Testing Association: quality than old stems; and green nique, and laboratory procedures. www.foragetesting.org leaves are higher in quality than ■ While protein and minerals can US Dairy Forage Research Center: dead leaves. In most cases, higher limit animal performance, www.dfrc.wisc.edu quality is also associated with digestible energy is more likely to legumes as compared to grasses; be the limiting factor from forage. and with cool-season plants as ■ compared to warm-season plants. The more mature and fibrous (lower in quality) a forage, the ■ Rain during field drying damages longer it takes to be digested and legume hay more than grass hay. the less an animal will consume. Also, the dryer the hay when rain ■ occurs, the greater the damage. Major losses in forage quality However, delayed harvest due to often occur due to poor storage concern about rain probably and feeding techniques. Producing results in more forage quality loss forage with good nutritive value is than does rain damage. not enough; good animal perform- ance results when animals consume forage that is suitably high in nutrients and low in fiber.

15 Glossary UNDERSTANDING FORAGE QUALITY Acid detergent fiber (ADF) The residue Bypass protein See rumen undegraded vitro digestibility, in situ digestibility, remaining after boiling a forage protein. near infrared reflectance analysis, or sample in acid detergent solution. ADF Cellulose A structural carbohydrate; a calculated from acid detergent fiber contains cellulose, lignin and silica, but long-chain polymer of glucose that is (which is the least accurate method). not hemicellulose. Often used to calcu- the main constituent of plant cell Escape protein See rumen undegraded late digestibility,TDN and/or NEl. walls. It is the most abundant carbohy- protein. Contrast with crude fiber and neutral drate in nature and is slowly and par- detergent fiber. Ether extract (EE) Portion of dry matter tially digestible by ruminants. extracted with ether. Used to measure Acid detergent fiber insoluble nitrogen Crude fat An estimate of the fat content crude fat. See crude fat and fat. (ADFIN) See acid detergent insoluble of feeds that is measured by ether nitrogen (preferred term). Fat Triglycerides of fatty acids that are a extraction. Crude fat contains true fat high density source of energy for Acid detergent fiber crude protein (triglycerides) as well as alcohols, animals. Fat is measured by determin- (ADFCP) See acid detergent insoluble waxes, terpenes, steroids, pigments, ing content of fatty acids or is esti- crude protein. ester, aldehydes, and other lipids. See mated in forages as ether extract Acid detergent insoluble crude protein ether extract and fat. minus one. Fats and fatty acids contain (ADICP) The same feed fraction as Crude fiber (CF) The original fiber 2.25 times the energy found in carbo- ADIN that has been converted to method using sequential acid and hydrates and are highly digestible by crude protein equivalent by multiply- alkali extraction (developed by animals. See ether extract and crude fat. ing ADIN * 6.25. Same as acid detergent Henneberg and Sttohmann in 1865). Hemicellulose Long chains of sugar com- fiber crude protein. ADICP is preferred. Crude fiber includes most of the cellu- pounds associated with plant cell walls. lose, but only a portion of the lignin Acid detergent insoluble nitrogen In situ digestibility Digestibility deter- (ADIN) Nitrogen in acid detergent and no ash.Therefore it underesti- mates true fiber, is less than ADF,and is mined by incubation of a ground fiber residue. ADIN greater than 15% of forage sample in a porous nylon bag nitrogen is an indicator of heat seldom used for forage analysis. Contrast with acid detergent fiber and within the rumen of an animal for a damage. Formation of ADIN is also fixed time period. called non-enzymatic browning neutral detergent fiber. (because the hay or silage turns Crude protein (CP) This value is 6.25 times In vitro digestibility See in vitro dry brown) or the Maillard reaction. Should the nitrogen content for forage or 5.7 matter digestibility (preferred term). be expressed as a percent of the dry times the nitrogen content for grain. In vitro dry matter digestibility (IVDMD) matter, not of ADF.Same as acid deter- Degraded intake protein (DIP) See Digestibility determined by incubation gent fiber insoluble nitrogen. rumen degraded protein. of a ground forage sample with rumen Adjusted crude protein (ACP) A calcu- fluid in beaker or test tube for 24 to 48 Digestible cell wall See digestible neutral hours, followed either by addition of lated value adjusting total crude detergent fiber (preferred term). protein for heat-damaged protein. acid and pepsin and further incuba- Adjusted crude protein estimates the Digestible neutral detergent fiber tion for 24 hours (IVDM or IVDMD) or protein available for animal use and (dNDF) The portion of neutral deter- by boiling in neutral detergent fiber should be used for formulating rations gent fiber digested by animals at a solution. See dry matter digestibility. when ADIN is greater than 15% of the specified level of feed intake.The In vitro NDF digestibility (IVNDFD) See total nitrogen. dNDF of feeds may be determined by digestible neutral detergent fiber. in vivo feeding trials or estimated by Ash (also called total ash) A measure of lignin analysis, in vitro or in situ Lignin Undigestible plant component, the total mineral content; the residue digestibility, or by near infrared giving the plant cell wall its strength remaining after burning a sample. reflectance analysis. Expressed on DM and water impermeability. Lignin also Values above 10% for grasses or 14% basis. Compare with neutral detergent reduces digestibility. for legumes usually indicate soil con- fiber digestibility. Metabolizable energy (ME) The energy tamination of forage. Ash, ADF-ash, Digestible energy (DE) The energy in a in a forage that is not lost in feces, and NDF-ash will be different values urine, or rumen gases. because ADF and NDF procedures forage or feedstuff that is not excreted remove some minerals. in feces. Metabolizable protein (MP) The rumen undegraded protein and microbial pro- As fed See as is. Dry matter (DM) The percentage of the sample that is not water. tein that passes into the intestine and As is Values expressed based on moisture can be broken down into amino acids. content of forage when it was received Dry matter digestibility (DMD) The portion of the dry matter in a feed that Modified crude fiber (MCF) A modifica- in the laboratory. Same as as fed and as tion of the crude fiber in which the received. is digested by animals at a specified level of feed intake. Called in vivo DMD ashing step is deleted. Modified crude As received See as is. if determined by feeding animals in a fiber is crude fiber plus ash. Available crude protein (ACP) Same as digestion trial.There is no laboratory Moisture The percent of the sample that adjusted crude protein. method for measuring DMD directly; it is water. is often estimated by measuring in 16 Figure 11. Feed and forage composition. analytical fractions chemical constituents other analyses Net energy for gain (NEg) An estimate of moisture water the energy value of a feed used for ash various minerals plus sand body weight gain above that required dry organic NDF ADF cellulose for maintenance. matter matter lignin fiber-bound N* ADICP,NDICP Net energy for lactation (NE ) An l age heat-damaged N*

estimate of the energy value of a feed or hemicellulose used for maintenance plus milk pro- fructans duction during lactation and for main- NDS glucans NDSF

tenance plus the last two months of eed or f NDSC pectic substances gestation for dry, pregnant cows. sugars starches Net energy for maintenance (NEm) An organic acids tage of f estimate of the energy value of a feed NPN (amino acids, amines, en used to keep an animal at a c urea) er

weight. p crude degradable RDP (DIP) protein true protein Neutral detergent fiber (NDF) Residue undegradable RUP (UIP) left after boiling a sample in neutral ether esterified fatty acids detergent solution. Called aNDF if extract pigments and waxes amylase and sodium sulfite are used during the extraction (this is recom- *Fiber-bound nitrogen and heat-damaged nitrogen are also found in crude protein and RUP. mended procedure).The NDF in Source: John Moore. Professor Emeritus of Animal Sciences, University of Florida. forages represents the indigestible and slowly digestible components in plant Nonstructural carbohydrate (NSC) See degraded to ammonia in the rumen. cell walls (cellulose, hemicellulose, total nonstructural carbohydrate; Same as degraded intake protein. lignin, and ash). Contrast with crude contrast with nonfibrous carbohydrate. Rumen degraded protein is the pre- fiber and acid detergent fiber. Nutritive value (NV) Protein, mineral, and ferred term. Neutral detergent fiber digestibility energy composition, availability of Rumen undegraded protein (RUP) That (NDFD) The portion of neutral deter- energy, and efficiency of energy utiliza- portion of the protein not degraded in gent fiber digested by animals at a tion. the rumen. Often called bypass protein, specified level of feed intake. May be Organic matter (OM) The portion of the escape protein, or undegraded intake determined by in vivo feeding trials or dry matter that is not ash (mineral). protein. Rumen undegraded protein is the preferred term. estimated by lignin analysis, by in vitro Organic matter digestibility (OMD) The or in situ digestibility, or by near portion of the organic matter that is Soluble intake protein (SIP) That portion infrared reflectance analysis. Expressed digestible. of total protein rapidly degraded to on NDF basis. Compare with digestible ammonia in the rumen. neutral detergent fiber. Protein A long chain of amino acids essential for plant and animal life. Soluble protein Protein soluble in a spec- Neutral detergent insoluble crude Animals meet protein needs by ified solution. Can be used to estimate protein (NDICP) Nitrogen in neutral breaking down plant and microbial rumen degraded protein and rumen detergent fiber residue. Estimates the (from the rumen) protein and reassem- undegraded protein. portion of the undegradable protein bling as animal protein. Total digestible nutrients (TDN) The that is available to the animal. Relative feed value (RFV) An index for sum of crude protein, fat (multiplied by Neutral detergent soluble carbohydrates ranking cool-season grass and legume 2.25), non-structural carbohydrates, (NDSC) See nonfibrous carbohydrates. forages based on combining and digestible NDF. Often estimated by Nonfibrous carbohydrate (NFC) An digestibility and intake potential. calculation from ADF,but formulas estimate of the rapidly available carbo- Calculated from ADF and NDF.The used vary. hydrates in a forage (primarily starch higher the RFV, the better the quality. It Total nonstructural carbohydrate (TNC) and sugars).This value is calculated is used to compare varieties, match A measure of the starch and sugar in from one of the following equations: hay/silage inventories to animals, and forages. It has a lower value than nonfi- NFC = 100% – (CP% + NDF% + EE% + to market hay. brous carbohydrates because NFC Ash%) or, if corrected for NDFCP, Relative forage quality (RFQ) An index contains compounds other than starch NFC% = 100% – [CP% + (NDF% – for ranking cool-season grass and and sugars. Same as nonstructural car- NDFCP%) + EE% + Ash%] Contrast legume forages based on TDN and bohydrate; contrast with nonfibrous with total nonstructural carbohydrate. intake potential. Calculated from NDF, carbohydrate. Non-protein nitrogen (NPN) The portion CP, EE, NDFD, ADF,and NFC. It matches Undegraded intake protein (UIP Same of the total nitrogen that is not in animal performance better than RFV as rumen undegraded protein. protein. If high, NPN is an indicator of across a wide range of forages. Voluntary intake Consumption of a potential for nitrate toxicity. Rumen degraded protein (RDP) That forage when forage availability is not portion of total protein that is limiting. 17

This publication has been endorsed by the American Forage and Grassland Council, the National Forage Testing Association, and The National Hay Association.

Authors Reviewers Sponsors Dr. Don Ball The authors gratefully acknowledge reviews Printing of this publication was funded by Extension Agronomist/ of this publication provided by: the following organizations: Alumni Professor Dr. Larry Chase ABI Alfalfa, Inc. Auburn University Associate Professor of Animal Sciences Agway Farm Seed Dr. Mike Collins Cornell University A.L. Gilbert Professor of Agronomy Dr. Marvin Hall American Farm Bureau Federation University of Kentucky Extension Agronomist/Professor American Farm Products Dr. Garry Lacefield Penn State University ANKOM Technology Barenbrug USA Extension Agronomist/Professor Dr. Mike Hutjens BASF Corporation University of Kentucky Extension Dairy Specialist Case IH Dr. Neal Martin Professor of Animal Sciences CelPril Director, U.S. Dairy Forage University of Illinois CROPLAN GENETICS Research Center Mr. Paul Meyer Dairyland Seed Co., Inc. USDA/ARS Commercial hay producer Forage Genetics International Dr. David Mertens West Point, Nebraska Foss North America, Inc. Dairy Scientist, U.S. Dairy Forage Dr. John Moore Grazing Lands Conservation Initiative Research Center Professor Emeritus of Animal Sciences Hesston/New Idea – AGCO Corporation USDA/ARS University of Florida IMC Global, Inc. JohnDeere.com Dr. Ken Olson Mr. Steve Orloff Land O’ Lakes Farmland Feed Dairy & Animal Health Specialist Extension Farm Advisor Mississippi Chemical Corporation American Farm Bureau Federation Yreka, California Mycogen Seeds Dr. Dan Putnam Natural Resources Conservation Service Extension Agronomist New Holland North America, Inc. Associate Professor Pennington Seed, Inc. University of California-Davis Pioneer Hi-Bred International, Inc. Dr. Dan Undersander Purina Mills, Inc. Extension Agronomist/Professor Research Seeds, Inc. University of Wisconsin Seedbiotics Mr. Mike Wolf Servi-Tech Labs/ Dodge City, JL Analytical Services KS & Hastings, NE Modesto, California Southern States Cooperative, Inc. State Farm Bureaus of Iowa, Idaho, Kansas, Michigan, Montana, Nebraska, New Hampshire, New Mexico, North Dakota, Oklahoma, South Dakota,, Texas, Utah, and Washington Vermeer Manufacturing Co. Vigortone Ag Products William H. Miner Agricultural Research Institute WL Research

Ball, D.M., M. Collins, G.D. Lacefield, N.P.Martin, D.A. Mertens, K.E. Olson, D.H. Putnam, D.J. Undersander, and M.W.Wolf. 2001. Understanding Forage Quality. American Farm Bureau Federation Publication 1-01, Park Ridge, IL