Suggested retail price $3.50

Understanding forage 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 forages 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 cattle 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 endophyte-infected 15,000 100 ) increase = $400 profit Indiana tall fescue e r Illinois c 12,000 )

a 80 /

hybrid - % (

b l e sudangrass (

t n 9,000 a r 60

sericea o i n t c lespedeza o i u t d 6,000 p 40

orchardgrass o e r c p n

& white clover o k l c annual i 3,000 20 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 $140 o

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 <75 75-86 87-102 103-124 125-150 >150 1 2 3 4 5 year forage quality (RFV)

1 U N D E R S T A N D I N G F O R A G E Q U A L I T Y

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 (cellulose, 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.

■ Digestibility How much of the Animal performance 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 digestion 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 Climate 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 timothy 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 harvest, 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 30 u 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 U N D E R S T A N D I N G F O R A G E Q U A L I T Y 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 climates 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 harvests 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 grain content and/or stover 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 U N D E R S T A N D I N G F O R A G E Q U A L I T Y 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. porportion 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 50 50 a 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 livestock? 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 ar various moisture levels. tion; if it smells of butyric acid— similar to rancid butter—it may lack 50 palatability, and low animal intake is storage loss likely.) harvest loss Dusty hay is usually the result of soil 40 barn-dried field-cured being thrown into the hay by rake 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 referred to as organoleptic qualities. r 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, silos wire, items of clothing, dead animals, 10 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 (%) farm animals.

Source: Michigan State University

7 U N D E R S T A N D I N G F O R A G E Q U A L I T Y

estimated from measured analyses. HOW TO PROPERLY Laboratory See figure 10 on page 17. SAMPLE HAY Dry matter—Dry matter (DM) is the analysis of forage portion (weight) of forage other than Use a good probe—The hay probe hough sensory evaluation is of water. Nutrients and other feed charac- should have an internal diameter of value, accurate laboratory testing of teristics are typically reported on a DM 3⁄ 8 to 5⁄ 8 inch.The cutting edge Tfeed and forage is required to basis to eliminate the dilution effect of should be at right angles to the shaft, provide the information needed to for- moisture and to allow more direct and kept sharp. Dull probes will not mulate animal rations.Testing to assess comparison of feeds and easier formu- obtain a representative sample. Core quality also provides a basis for com- lation of diets. Dry matter percentages samplers that cut through a cross- mercial hay sales. should be used to adjust as-received section of a bale provide the best rep- tonnages to determine true yields of resentation of stems and leaves. Avoid A forage analysis should reflect the forage and to determine the actual using open augers as they selectively average quality of the material being amount of forage (without the water) sample leaves. tested. Only a few grams of material represents tons of forage, so it is being bought or sold.To compare Sample at random—It is important essential to obtain a representative prices and nutritive value among lots to select bales at random from sample.Therefore, sampling technique of forage they should be adjusted to a throughout the hay “lot” (defined in is extremely important (see sidebars DM basis. Sometimes hay is compared sidebar on page 10). Avoiding some on how to properly sample hay, silage, or sold on a 90% DM basis, which bales and choosing others based on and pasture forage). closely resembles the average DM of appearance will bias the sample. For air dried feeds. stacked hay, samples should be taken For hay, excessively low from bales at various heights in the moisture (less than 10%) could stack. indicate brittleness (and thus Take enough core subsamples— low palatability) or excessive Taking at least 20 core samples from a leaf loss (linked with lowered hay lot minimizes sample variation. forage quality), while high Use the proper technique—For rec- moisture (greater than 14 to tangular bales of all sizes, insert the 18%) indicates a risk of mold. hay probe 12 to 18 inches deep at a For silage, excessively low right angle into the center of the ends moisture (below 45%) can of bales. For round bales, the probe indicate heat damage, while should be inserted at right angles to high moisture (above 70%) can the outside circumference of the indicate poor fermentation bales. and potential intake problems. Handle samples correctly—Combine Detergent fiber analysis—Acid core samples from a given lot into a Laboratory detergent fiber (ADF) and neutral single sample and store in a sealed analytical techniques detergent fiber (NDF) are frequently plastic freezer bag. Samples should be used as standard forage testing tech- protected from heat or direct sun, and Laboratory analyses are used to deter- niques for fiber analysis. Forage promptly sent to a laboratory for mine the nutritive value of forages. A samples are boiled in either a deter- analysis. The sample should weigh typical forage analysis includes meas- gent solution (for NDF) or with added urements of dry matter, crude protein, approximately 1 ⁄ 2 to 3 ⁄ 4 pound. With acid (for ADF) according to defined larger samples, many labs will not and fiber (acid detergent fiber and protocols.The residue is the NDF or grind the entire sample.Too small a neutral detergent fiber). Sometimes ADF fraction. NDF approximates the sample will not adequately represent ash is measured, and when heat- total cell wall constituents including the hay lot. damaged protein is suspected, acid hemicellulose, whereas ADF primarily detergent insoluble crude protein represents cellulose, lignin, and ash. Split samples correctly—To test the should be measured. Many other ADF is often used to calculate performance of a particular laboratory results provided on laboratory reports digestibility, and NDF is used to (or the sampling technique), a fully (digestible energy or protein, net predict intake potential. As fiber ground and thoroughly mixed sample energy, total digestible nutrients, increases, forage quality declines. should be split and submitted. potential intake, etc.) are calculated or Unground samples should not be split.

8 Protein—Protein is a key nutrient that must be considered both in amount HOW TO PROPERLY SAMPLE SILAGE and type for various animal diets. It is Sampling during harvesting commonly measured as crude protein Collect three to five handfuls of chopped forage from the middle of a load (CP), which is 6.25 times the nitrogen during unloading, place in a plastic bag, and refrigerate immediately. Follow content of forage. Crude protein is used the same procedure for several loads throughout the day. Combine samples because rumen microbes can convert from a single harvested field and mix well. Place the entire sample in a clean non-protein nitrogen to microbial plastic bag or other container, and seal tightly. Label each container with your protein, which can then be used by the name and address as well as the date, sample number, and forage type. Store animal. However, this value should be the sample in a cool place (do not freeze) until you send it to a laboratory for used with some care, as it is not appli- analysis. Repeat for each field, variety, or hybrid. If filling tower silos or silo cable to non-ruminants or when high tubes, keep a record of where each lot is in the silo or tube. Feeding colored levels of nitrate are present in the plastic strips through the blower at the end of each lot may help identify the forage. lots later. High-performing animals, especially Silos with seepage should be resampled upon feeding because loss of milking dairy cows, need larger soluble compounds due to seepage will increase dry matter, acid detergent amounts of protein to be absorbed fiber and neutral detergent fiber, and decrease crude protein. Similarly, from the intestines than rumen resample silos at feeding that were filled with forage at less than 50% microbes produce.Therefore, they need moisture that may have heated excessively, causing increased acid detergent a certain amount of bypass protein (or fiber and acid detergent fiber insoluble nitrogen. Recheck dry matter of RUP) in the ration. Recently, calibrations at feed out. Fiber and protein are not likely to change much during have been developed that allow RUP in storage, except as mentioned above, but moisture can change significantly. forages to be estimated using near infrared reflectance spectroscopy. Ensiled material from a tower silo Do not sample the spoiled material on the top or bottom of the silo; wait Acid detergent insoluble nitrogen until 2 to 3 feet of silage have been removed. Collect a 1 to 2 pound sample (ADIN)—This estimates the nitrogen from the silo unloader while it is operating. Collect samples from opposite that has low digestibility in the rumen sides of the silo. Combine the samples and mix well. Place the entire sample and the intestine. It is important for in a plastic bag and handle as discussed above. determining the value of heat- damaged hay and silage. A little ADIN Ensiled material from a bunker silo is good because it increases bypass If feeding with a TMR (total mixed ration) mixer—Load silage from bunker protein, but too much may reduce into TMR mixer and mix well.Take several grab samples to collect a 1 to 2 total protein availability. pound total sample. Place in a plastic bag and handle as discussed above. Digestible energy estimates— If not feeding with a TMR mixer—Collect a 1 to 2 pound total sample from Energy values are estimates of feeding the different vertical layers of the silo face. Grab several handfuls from freshly trial results.The vast majority are cal- exposed forage after the day’s feeding has been removed. Do not sample the culated, not measured, values.There spoiled material on top of the silo. Combine handfuls and mix well. Place the are four basic approaches: entire sample in a clean plastic bag or other container, and seal tightly. Store A. The most common has been to immediately in a cold place until shipping. Label each container as indicated measure a single fiber fraction earlier. Place in a plastic bag and handle as discussed above. (usually acid detergent fiber) and use it to predict digestibility, total digestible nutrients (TDN) or net energy for lactation (NEl). B. Summative equations are predic- tions of TDN or NEl from multiple measures of forage composition. These measures often include neutral detergent fiber (NDF), NDF nitrogen, crude protein, ether extract, lignin, and acid detergent

9 U N D E R S T A N D I N G F O R A G E Q U A L I T Y

fiber nitrogen.These predictions Intake estimates—Voluntary intake, a IDENTIFICATION can be much more accurate than prime consideration in feeding, is those of single fiber fractions, but often estimated based on neutral OF A FORAGE LOT are much more time consuming detergent fiber (NDF) content. NDF A lot is defined as forage taken and expensive. Beware of laborato- consists of the slowly digested and from the same farm, field, and cut ries that output “summative equa- nondigestible fibrous portion of the under uniform conditions within a tions” but don’t measure all com- plant (mostly hemicellulose, cellulose, 48-hour time period. A lot can rep- ponents. lignin, and ash) which is most of the resent several truck or wagon C. In vitro and in situ digestibility are cell wall material (figure 7). As the NDF loads, but all the forage should generally considered the best level increases, voluntary feed intake have been harvested and stored analyses to use to predict animal tends to decline. However, if NDF of under identical conditions. For performance. Both use rumen fluid the ration is too low, health problems accurate test results, hay or silage to digest the samples either in a such as acidosis, displaced aboma- should be stored by lots, and beaker or test tube (in vitro) or in a sums, and foundering may occur. separate samples taken from each porous bag placed in the rumen lot. Any special conditions that via a fistula or port in the animal’s Laboratory result in quality differences in a lot, side (in situ). such as rain damage during harvest proficiency D. Some scientists have begun or excessive weed populations, The accuracy of forage analysis should be noted to allow later looking for additional factors to better describe the energy content depends on the analytical procedures assessment of the reasons for used and the precision of laboratory quality variations. of forage.The most common addi- tional measure at present is to techniques.The National Forage Testing determine nonfibrous carbohy- Association (NFTA) certifies the profi- drate (NFC) or starch content.This ciency of laboratories with regard to is an especially good approach to accurately testing hay and corn silage use with high NDF or high starch for DM, CP, ADF, and NDF. It is advisable feeds. (See “NFC” in the glossary.) to use a NFTA certified laboratory. For a current listing of certified laborato- ries, as well as more information about proficiency testing, visit NFTA’s web site (www.foragetesting.org). When evaluating a forage test report, keep in mind that none of the values, either measured or calculated, should Figure 7. Structural components of alfalfa. be considered absolute.There is vari- ability in hay stacks or silage, and some variation associated with lab analysis. Normal lab variation, not including errors associated with poor leaves: 18-28% NDF Non-structural 12-20% ADF carbohydrates (NSC) sampling of forages, are considered to 22-35% CP (sugars & starch) be: CP (+/-0.5), NDF (+/-0.9), and ADF 25-35% (+/-0.7). For example, a reported value stems: 35-70% NDF Structural of 20% CP should be considered to be 30-55% ADF carbohydrates anywhere between 19.5 and 20.5% 10-20% CP (NDF: cellulose, under normal circumstances. Relative hemicellulose, cell contents (NSC) & lignin; feed value (see glossary) will vary 100% digestible 30-50% ADF: cellulose & lignin) within 8 points. Proteins Plant 15-25% (soluble & bound) cell 2-3% Oils (lipids) 8-13% Ash (minerals) cell wall (NDF) Whole plant 20-60% digestible Whole plant analysis Adapted from: Putnam, Dan, 2000. Producing high quality alfalfa: Factors that influence 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 t sis repor This seal indicates the analy ry Feed Laborato lab has passed the Analysis ABC Feed reet NFTA proficiency test. where St Any 00 00 ty, ST 000 0-000-00 Any Ci 0 Fax: 00 com -000-000 ww.ABC. Feed description The hone: 000 Web: w A-1-720 P [email protected] n: il: ABCLa ntificatio alfa client needs to provide Ema Feed ide Alf Client identification farm accurate and detailed lient ed type: Doe Helps ensure infor- Joe C Fe d origin: 20 street er or fee South 7 information about the t name: 123 Any Grow 5/01 mation is reported Clien AS 12345 cation: First, 05/2 forage or feed to aid in s: nytown, Field lo t date: lage Addres A d harves ted for si to correct person Zip 456-7890 utting an Wil interpretation. ity, State, 123- C ation: oe or organization. C alnet.com d preserv John D ne: JC@loc Fee Pho r: 05/25/01 Sample : Email: le taken 26/01 9/01 ate samp 05/ 05/2 D shipped: 01 nalyzed: 1 sample 05/28/ sample a 05/31/0 Date eived: Date rted: mple rec ults repo -000123 Date sa s. Date res de: 00 12 load cation co terial from b identifi : 4567 ped ma ndition. La ion code s of chop good co Sample identity e/access b sample mount in M Invoic dling: Gra equate a 90% D and han rial of ad DM and description method ped mate 100% Sample ed: Chop ived Report should list as receiv As rece ondition 10.0 Sample c Method lot identification 0.0 90.0 s .0 number, sampling nts, unit 65 100.0 .6 Nutrie s 5-16 21 mination house 10 35.0 24.0 date, sample cal deter In- 6 26.1 Analyti use 105-1 8.4 .0 method and isture, % In-ho 29 34.2 Oven mo 90.03 0.2 atter, % AOAC 9 1 38.0 handling, and en dry m 379 Ov % ndbook 13.3 protein, Ha 10.8 condition of the Crude er, % 1993 0 rgent fib NFTA, 12. 3.6 sample on arrival. Acid dete 4.2 4.0 9.0 DF, % 3 4 aN tural mith, 198 1. 10.0 nonstruc S A Total C 920.39 3.5 ydrates, % AOA 2.07 carboh 42.05 AOAC 9 2.30 30 , % 0. Fat 0.81 0.33 , % ion Ash ISI equat 0.12 Analytical results Results s NIR quation Mineral -house e % NIR in 21.6 should be reported on a Calcium, us, % 24.0 54.5 100% dry matter (DM) hosphor .4 P ues 8 60.6 1 ated val 8 0.6 basis. Additional columns Calcul le tens, 198 21.2 .68 det. solub Mer 989 0 146.0 Neutral Marble, 1 .24 may be included for rates, % Bath & 0 162.0 arbohyd s, % g. ADF c nutrient ertens le 56.8 reporting results on an igestible al/lb M Total d ation, Mc , 1993 as-is (as-received) or an gy of lact 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. derived or calculated from analytical determinations.

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 sheep 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 goats 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 U N D E R S T A N D I N G F O R A G E Q U A L I T Y 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 8. 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 8. 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 9). 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 average daily gain 1.5 lb m

y (as in a properly grazed pasture), boot

r first calf heifer d (when most hay should be harvested), e l 60 beef cow/calf to b i and mature (when much hay actually t wean 500 lb calf 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-seaso n 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 9. 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 U N D E R S T A N D I N G F O R A G E Q U A L I T Y Acid detergent fiber (ADF) The residue Available crude protein (ACP) Same as vitro digestibility, in situ digestibility, remaining after boiling a forage adjusted crude protein. near infrared reflectance analysis, or sample in acid detergent solution. ADF Bypass protein See rumen undegraded calculated from acid detergent fiber contains cellulose, lignin and silica, but protein. (the least accurate method of determi- not hemicellulose. Often used to calcu- nation). late digestibility, TDN and/or NEl. Cellulose A structural carbohydrate; a long-chain polymer of glucose that is Escape protein See rumen undegraded Contrast with crude fiber and neutral protein. detergent fiber. the main constituent of plant cell walls. It is the most abundant carbohy- Ether extract (EE) Portion of dry matter Acid detergent fiber insoluble nitrogen drate in nature and is slowly and par- extracted with ether. Used to measure (ADFIN) See acid detergent insoluble tially digestible by ruminants. crude fat. See crude fat and fat. nitrogen (preferred term). Crude fat An estimate of the fat content Fat Triglycerides of fatty acids that are a Acid detergent fiber crude protein of feeds that is measured by ether high density source of energy for (ADFCP) See acid detergent insoluble extraction. Crude fat contains true fat animals. Fat is measured by determin- crude protein. (triglycerides) as well as alcohols, ing content of fatty acids or is esti- Acid detergent insoluble crude protein waxes, terpenes, steroids, pigments, mated in forages as ether extract (ADICP) The same feed fraction as ester, aldehydes, and other lipids. See minus one. Fats and fatty acids contain ADIN that has been converted to ether extract and fat. 2.25 times the energy found in carbo- crude protein equivalent by multiply- Crude fiber (CF) The original fiber hydrates and are highly digestible by ing ADIN * 6.25. Same as acid detergent method using sequential acid and animals. See ether extract and crude fat. fiber crude protein. alkali extraction (developed by Forage quality The ability of a forage to Acid detergent insoluble nitrogen Henneberg and Sttohmann in 1865). support desired levels of animal per- (ADIN) Nitrogen in acid detergent Crude fiber includes most of the cellu- formance (e.g., daily gain or milk pro- fiber residue. ADIN greater than 15% of lose, but only a portion of the lignin duction). It is a function of voluntary nitrogen is an indicator of heat and no ash.Therefore it underesti- intake and nutritive value. damage. Formation of ADIN is also mates true fiber and is less than ADF. It Hemicellulose Long chains of sugar com- called non-enzymatic browning is seldom used for forage analysis. pounds associated with plant cell walls. (because the hay or silage turns Contrast with acid detergent fiber and brown) or the Maillard reaction. Should neutral detergent fiber. In vitro digestibility See in vitro dry matter digestibility (preferred term). be expressed as a percent of the dry Crude protein (CP) This value is 6.25 times matter (preferred) or of the nitrogen, the nitrogen content for forage or 5.7 In vitro dry matter digestibility (IVDMD) not of ADF. Same as acid detergent fiber times the nitrogen content for grain. Digestibility determined by incubation insoluble nitrogen. of a ground forage sample with rumen Degraded intake protein (DIP) See fluid in beaker or test tube for 24 to 48 Acid insoluble lignin Lignin measured rumen degraded protein. using sulfuric acid. See lignin. hours, followed either by addition of Digestible cell wall See digestible neutral acid and pepsin and further incuba- Adjusted crude protein (ACP) A calcu- detergent fiber (preferred term). tion for 24 hours (IVDM or IVDMD) or lated value adjusting total crude Digestible neutral detergent fiber by boiling in neutral detergent fiber protein for heat-damaged protein. solution. See dry matter digestibility. Adjusted crude protein estimates the (dNDF) The portion of the neutral protein available for animal use and detergent fiber digested by animals at In vitro NDF digestibility (IVDNFD) See should be used for formulating rations a specified level of feed intake.The digestible neutral detergent fiber. when ADIN is greater than 15% of the dNDF of feeds may be determined by In situ digestibility Digestibility deter- total nitrogen. in vivo feeding trials or estimated by mined by incubation of a ground lignin analysis, in vitro or in situ Ash (also called total ash) A measure of forage sample in a porous nylon bag digestibility, or by near infrared within rumen of an animal for a fixed the total mineral content; the residue reflectance analysis. remaining after burning a sample. time period. Values above 10% for grasses or 14% Digestible energy (DE) The energy in a Lignin Undigestible plant component, for legumes usually indicate soil con- forage or feedstuff that is not excreted giving the plant cell wall its strength tamination of forage. Ash, ADF-ash, in feces. and water impermeability. Lignin also and NDF-ash will be different values Dry matter (DM) The percentage of the reduces digestibility. because ADF and NDF procedures sample that is not water. Metabolizable energy (ME) The energy remove some minerals. Dry matter digestibility (DMD) The in a forage that is not lost in feces, As fed See as is. portion of the dry matter in a feed that urine, or rumen gases. As is Values expressed based on moisture is digested by animals at a specified Metabolizable protein (MP) The rumen content of forage when it was received level of feed intake. Called in vivo DMD undegraded protein and microbial pro- in the laboratory. Same as as fed and as if determined by feeding animals in a tein that passes into the intestine and received. digestion trial.There is no laboratory can be broken down into amino acids. method for measuring DMD directly; it As received See as is. is often estimated by measuring in 16 Figure 10. Feed and forage composition.

analytical fractions chemical constituents other analyses Modified crude fiber (MCF) A modifica- moisture water tion of the crude fiber in which the ash various minerals plus sand ashing step is deleted. Modified crude dry organic NDF ADF cellulose fiber is crude fiber plus ash. matter matter lignin

e fiber-bound N* ADICP, NDICP

Moisture The percent of the sample that g

a heat-damaged N* r

is water. o hemicellulose f

r fructans Net energy for gain (NEg) An estimate of o

d NDS glucans NDSF

the energy value of a feed used for e

e NDSC pectic substances f body weight gain above that required f sugars o for maintenance.

e starches g

Net energy for lactation (NEl) An a organic acids t

n NPN (amino acids, amines,

estimate of the energy value of a feed e c used for maintenance plus milk pro- r urea) e

duction during lactation and for main- p crude degradable RDP (DIP) protein true protein tenance plus the last two months of undegradable RUP (UIP) gestation for dry, pregnant cows. ether esterified fatty acids Net energy for maintenance (NEm) An extract pigments and waxes estimate of the energy value of a feed *Fiber-bound nitrogen and heat-damaged nitrogen are also found in crude protein and RUP. used to keep an animal at a stable Source: John Moore. Professor Emeritus of Animal Sciences, University of Florida. weight. Neutral detergent fiber (NDF) Residue Non-protein nitrogen (NPN) The portion Rumen degraded protein is the pre- left after boiling a sample in neutral of the total nitrogen that is not in ferred term. detergent solution. Called aNDF if protein. If high, NPN is an indicator of Rumen undegraded protein (RUP) That amylase and sodium sulfite are used potential for nitrate toxicity. portion of the protein not degraded in during the extraction (this is recom- Nonstructural carbohydrate (NSC) See the rumen. While often called bypass mended procedure).The NDF in total nonstructural carbohydrate; protein, escape protein, or undegraded forages represents the indigestible and contrast with nonfibrous carbohydrate. intake protein. Rumen undegraded slowly digestible components in plant protein is the preferred term. cell walls (cellulose, hemicellulose, Nutritive value (NV) Protein, mineral, and lignin, and ash). Contrast with crude energy composition, availability of Soluble intake protein (SIP) That portion fiber and acid detergent fiber. energy, and efficiency of energy utiliza- of total protein rapidly degraded to tion. ammonia in the rumen. Neutral detergent insoluble crude protein (NDICP) Nitrogen in neutral Organic matter (OM) The portion of the Soluble protein Protein soluble in a spec- detergent fiber residue. Estimates the dry matter that is not ash (mineral). ified solution. Can be used to estimate portion of the undegradable protein Organic matter digestibility (OMD) The rumen degraded protein and rumen that is available to the animal. portion of the organic matter that is undegraded protein. Neutral detergent soluble carbohydrates digestible. Total digestible nutrients (TDN) The (NDSC) See nonfibrous carbohydrates. Protein A long chain of amino acids sum of crude protein, fat (multiplied by 2.25), non-structural carbohydrates, Neutral detergent solubles (NDS) The essential for plant and animal life. Animals meet protein needs by and digestible NDF.TDN is often esti- portion of the forage that is soluble in mated by calculation from ADF.The neutral detergent solution and there- breaking down plant and microbial (from the rumen) protein and reassem- formulas for calculating TDN vary by fore is not neutral detergent fiber. region and by nutritionist. Usually assumed to be 98% digestible. bling as animal protein. Total nonstructural carbohydrate (TNC) Neutral detergent soluble fiber (NDSF) Relative feed value (RFV) An index for ranking cool-season grass and legume A measure of the starch and sugar in Neutral detergent soluble material forages. It has a lower value than nonfi- undigestible by animal enzymes. forages based on combining digestibility and intake potential. brous carbohydrates because NFC Nonfibrous carbohydrate (NFC) An Calculated from ADF and NDF.The contains compounds other than starch estimate of the rapidly available carbo- higher the RFV, the better the quality. It and sugars. Same as nonstructural car- hydrates in a forage (primarily starch is used to compare varieties, match bohydrate; contrast with nonfibrous and sugars).This value is calculated hay/silage inventories to animals, and carbohydrate. from one of the following equations: to market hay. Undegraded intake protein (UIP) Same NFC = 100% – (CP% + NDF% + EE% + as rumen undegraded protein. Ash%) or, if corrected for NDFCP, Rumen degraded protein (RDP) That NFC% = 100% – [CP% + (NDF% – portion of total protein that is Voluntary intake Consumption of a NDFCP%) + EE% + Ash%] Contrast degraded to ammonia in the rumen. forage when forage availability is not with total nonstructural carbohydrate. Same as degraded intake protein. 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 Forage Genetics International USDA/ARS Commercial hay producer Foss North America, Inc. Dr. David Mertens West Point, Nebraska Grazing Lands Conservation Initiative Dairy Scientist, U.S. Dairy Forage Dr. John Moore Heston/New Idea – AGCO Corporation Research Center Professor Emeritus of Animal Sciences IMC Global, Inc. USDA/ARS University of Florida Land O’ Lakes Farmland Feed Mississippi Chemical Corporation Dr. Ken Olson Mr. Steve Orloff Mycogen Seeds Dairy & Animal Health Specialist Extension Farm Advisor Natural Resources Conservation Service American Farm Bureau Federation Yreka, California New Holland North America, Inc. Dr. Dan Putnam Pennington Seed, Inc. Extension Agronomist Photography credits Pioneer Hi-Bred International, Inc. Associate Professor Don Ball Purina Mills, Inc. University of California-Davis Garry Lacefield Research Seeds, Inc. Dr. Dan Undersander Steve Orloff Seedbiotics Extension Agronomist/Professor Servi-Tech Labs/ Dodge City, University of Wisconsin KS & Hastings, NE Mr. Mike Wolf State Farm Bureaus of Iowa, Idaho, Kansas, JL Analytical Services Michigan, Nebraska, New Mexico, Modesto, California Oklahoma, South Dakota, Tennessee, Texas, and Utah 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 Suggested retail price $3.50

Understanding forage quality

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