Alfalfa Management Guide—Harvest (3 of 3)

47_______________________________________________________________________________________________________________________________________ E S T A B L I S H M E N T ________________

The final step to profitable

alfalfa production is to set goals

for forage quality and use the

appropriate harvest techniques

to minimize field losses and

maximize tonnage of high

quality forage. This recognizes

that high quality forage is prof-

itable to animals that can use

the quality but that tradeoffs

exist between forage quality,

yield, and stand life.

Harvest

Published byASA, CSSA, and SSSA

All copyrights reserved 2004

48

Forage quality

Alfalfa is superior to other foragecrops because it is high in crude

protein and energy, reducing the needfor both types of supplements inrations. The superior intake potentialallows for greater use in rations ofhigh-producing dairy cows.

What quality forage isneeded?The nutrient need of an animal dependsprimarily on its age, sex, and produc-tion status (figure 19). Maximum profitresults from matching forage quality toanimal needs. Lower-than-optimumquality results either in reduced animalperformance or increased supplementcosts. Conversely, feeding animalshigher quality forage than they needwastes unused nutrients that wereexpensive to produce and may result inanimal health problems.

Quality standards are presented intable 12. (Forage quality terms aredefined at the end of the Harvestsection.) Use the RFV index to allocatethe proper forage to the proper live-stock class (figure 19). Performance ofhigh-producing dairy cows is mostlimited by intake of digestible drymatter and prime hay or haylage isrecommended. An RFV or RFQ of 151or higher is recommended for dairy

cows after the first trimester, heifers,and stocker cattle. As shown in figure 20, ADF is a poorestimate of energy in feedstuffs. Inresponse, the National ResearchCouncil Nutrient Requirements forDairy Cattle (2001) recommendedestimating energy from totaldigestible nutrients (TDN). TDN isthe sum of digestible components(nonfibrous carbohydrates, crude

_______________________________________________________________________________________________________________________________________________________ H A R V E S T ______________

relative feed value/relative forage quality

100 110 120 130 140 150 160

n heifer, 12–18 mo.n beef cow with calf

n dairy, last 200 daysn heifer, 3–12 mo.n stocker cattle

n heifer, 18–24 mo.n dry cown idle horse

n brood maren working horse

n nursing maren hard-working horse

n dairy, 1st trimestern dairy calf

Figure 19. Forage quality needs of cattle and horses.

Table 12. Quality standards for legume, grass, andgrass-legume mixture.

RFV or RFQa ADF NDF

> 151 < 31 <40

151–125 31–35 40–46

124–103 36–40 47–53

102–87 41–42 54–60

86–75 43–45 61–65

<75 >45 >65

Abbreviations: RFQ = relative forage quality; RFV = relative feed value; ADF = acid detergent fiber; NDF = neutral detergent fiber.

a Assumes a neutral detergent fiber digestibility (NDFD) value of 45 or higher.



protein, fatty acids, and digestiblefiber). If NDFD is not reported on labanalyses, TDN was likely estimatedfrom ADF only and is much lessaccurate.RFQ was designed to use the newanalyses that better predict animalperformance. It is based on energyintake estimates relative to a stan-dard just like RFV was. The onlydifferences are that intake is adjustedfor digestible fiber and that energy iscalculated as TDN using digestiblefiber. This calculation allows moremeaningful comparisons betweenalfalfa, alfalfa-grass mixtures, andgrasses.

Plant growth and forage qualityUnderstanding how alfalfa grows andits relationship to forage yield, foragequality, and carbohydrate rootreserves is critical to production ofhigh quality hay. Alfalfa is a perennialplant that stores carbohydrates (sugarsand starches) in the crown and root.Plants use these carbohydrate reservesfor regrowth both in the spring andafter each cutting. When alfalfa is 6 to8 inches tall, it begins replacing carbo-hydrates in the root (figure 21). Thiscycle is repeated after each cutting.

High levels of carbohydrate reservesencourage rapid regrowth aftercutting and winter survival. Regrowthbegins with buds either on the crownor at the base of old shoots (after firstcutting). Alfalfa regrowth for secondand later cuttings begins whilegrowth from the previous cycle isbeginning to flower. Cutting at latematurity can remove shoots for thenext cutting and delay regrowth. Forage growth is most rapid untilearly flowering (figure 22). Foragegrowth continues until full flower, butoften leaf losses from lower stemsslow yield increase after first flower.Alfalfa forage quality is greatest inearly vegetative stages when the leafweight is greater than stem weight;however, by first flower, and some-times earlier, stem proportion exceedsthat of leaves. Higher alfalfa yieldsafter early flower can be attributedmainly to more low-quality stems. Ascutting interval increases or as plantsare harvested at later stages of matu-rity, yield per cutting increases butquality of the forage harvesteddecreases.

49_______________________________________________________________________________________________________________________________________ E S T A B L I S H M E N T ________________

80

70

60

50

40

dig

est

ibil

ity

(% d

ry m

atte

r ba

sis)

20 30 40 50 60

acid detergent fiber (%)

Figure 20. Comparison of ADF to in vitro digestibility of alfalfa.

growthinitiation

6-8 inchheight

budstage

fullbloom

roo

t c

arb

oh

ydra

te

cut at bloom

cut at bud

Figure 21. Carbohydrate content of alfalfa roots.

Figure 22. Forage yield relative to quality at different growth stages.

forage yield

stem yield

foragedigestibility

leaf yield

vegetative bud first flower full-flower post-flower



Temperatures during growth affectforage quality. Alfalfa grown duringcool weather tends to produce higherquality forage than alfalfa grownduring warm periods, assuming allharvests are equally weed-free and atthe same maturity stage.Forage quality is also influenced bythe time of day alfalfa is cut. Plantsconvert sugars and starches to energyin a process called respiration. Respi-ration after cutting lowers foragequality and is stopped only by dryingthe forage. Therefore, the best time tocut alfalfa is in the morning to speeddrying and capture sugars and starchfor higher quality hay and haylage.

Harvest management

Forage yield, quality, and standpersistence are all major considera-

tions in the development of a prof-itable harvest management program.Increased awareness of the nutritionalvalue of high quality alfalfa in terms ofpotential savings of energy and proteinsupplements has caused many to re-evaluate current harvest strategies.

Cutting scheduleSelection of a harvest schedule beginswith the decision on quality of foragedesired. Growers desiring all highquality alfalfa will shorten standpersistence and decrease yield.Harvest schedule decisions includenumber of cuts per season, date ofcut, stage of maturity, intervalbetween cuts, and cutting height. Thelink between the stage of maturityand yield, quality, and persistencemakes it apparent why growth stageis frequently used to decide when toharvest alfalfa. Keying harvests tospecific stages of development alsotakes into account the varying effectsof changing environments and varietymaturity rates. A shortened growingseason in northern states dictatescombining calendar dates and stage ofdevelopment into harvest strategies.

Maximum persistenceIf harvesting for maximum persistence,cut alfalfa between first flower and 25%flower. This is approximately 35 to 40days between cuttings (figure 23). Thesystem has a slightly wider harvestwindow and longer cutting intervalthan when cutting for high qualitybecause the emphasis is on high yield.

High qualityWhen harvesting for high quality thefirst cutting should be taken by anearly calendar date appropriate forthe region. The remainder of cuttingsshould be taken at midbud, generally28- to 33-day intervals early in theseason and longer near the end of theseason (figure 23). Cutting for highquality forage means that forage mustbe harvested within a 3- to 4-dayperiod. No late-fall cutting should betaken in northern states, although itshould be taken in regions whereneeded to decrease insect overwinter-ing. Yield of the late fall cutting isgenerally low and removal of thisforage will increase winterkill anddecrease first cutting yield the nextspring.

50 _______________________________________________________________________________________________________________________________________________________ H A R V E S T ______________

persistence

quality

yield and quality

10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160

no cutting recommended

no cutting recommended

June 1 July 1 Aug. 1 Sept. 1 Oct. 1 Oct. 27

recommended time to cut

cutting interval (days after May 25)

2 8 – 3 3 d ay s 3 0 – 3 5 d ay s

2 8 – 3 3 d ay s 3 8 – 5 5 d ay s

3 5 – 4 0 d ay s

3 0 – 3 5 d ay s

3 5 – 4 0 d ay s

Figure 23. Cutting schedules for different management goals.



51_______________________________________________________________________________________________________________________________________ E S T A B L I S H M E N T ________________

High yield and high qualityFor harvest schedules to provide thehighest yield of high quality forage, thefirst two cuttings must be timely.During this time forage quality changesmost rapidly and short delays meanlow quality forage (figure 24). Take thefirst cutting at bud stage or betweenMay 15 and 25 in Minnesota andWisconsin, and earlier farther south.Take the second cutting 28 to 33 daysafter the first cut or midbud, whicheveris earlier, and take subsequent cuttingsat 38- to 55-day intervals or at 10 to25% bloom. An early first harvestfollowed by a short cutting intervalgives a high yield of quality forage(figure 23) while letting one cuttingmature to early flower will increaseroot reserves and stand persistence.The forage quality of alfalfa does notchange as rapidly in later cuttings as inearlier cuttings so later cuttings main-tain quality to later maturity stages(figure 24). This slower quality changeallows a harvest window of 7 to 10days. Additional cuttings may be takenif time permits before the required 6- to8-week rest period prior to the firstkilling frost. In northern regions, delay-ing the third cut often results in alfalfaflowering during the 6 weeks beforethe first killing frost (between Septem-ber 1 and October 15 in northernstates). To prevent loss of persistence,delay harvest until mid- to lateOctober, regardless of the stage ofmaturity. However, this late-fall cuttingwill shorten stand life and decreaseyield the next spring, so should be cuthigh (at 6 inches) or not harvested ifadequate forage is available. Minnesotaresearchers found that highest yieldscame from three cuttings during thegrowing season with a late-fall cutting.Using this cutting schedule, thepercentage of total yield cut at “primestandard” (>150 RFV index) rangedfrom 32 to 75%.

Fall management

Fall management of alfalfa involvesassessing the risk of winter injury

and the need for additional forage.The risk of winter injury to alfalfadepends on uncontrollable environ-mental factors (snow cover, tempera-ture, and soil moisture) and control-lable factors (variety, soil fertility,seasonal cutting strategy, stand age,and cutting height).

Uncontrollable environmentalfactors

n Extended periods of cool tempera-tures are required in the fall foralfalfa to develop resistance tocold temperatures. Suddenchanges from warm to cold reducehardening.

n A snow cover of 6 inches or moreprotects alfalfa plants from severecold. During winters withoutsnow cover, soil temperatures canfall below 15°F, injuring or killingplants.

n Even hardy varieties can beinjured or killed by 2 weeks ormore of temperatures below 5° to 15°F.

n Warm fall weather (40°F or higher)and midwinter thaws cause alfalfato break dormancy and have lessresistance to freezing.

n Excessively moist soil in the fallreduces hardening and predis-poses alfalfa to winter injury.Excess surface and soil moisturecan lead to the formation of icesheets. Ice sheets smother plantsby freezing the soil before theplant has hardened. Also, highconcentrations of toxicsubstances—such as carbondioxide, ethanol, and methanol—accumulate beneath the ice. Icesheeting frequently occurs inconjunction with midwinterthawing and is more prevalent inpoorly drained soils.

Controllable factorsn Select alfalfa varieties with good

winterhardiness and moderateresistance to several diseases.These varieties will better toleratelate-fall cuttings.

5/25 6/1 28 35 45 35 39 47 62 63 35 39 45 69rela

tive

fe

ed

va

lue

yie

ld (

tons

/acr

e)

1st cutting 2nd cutting 3rd cutting 4th cutting

cutting intervals (days after previous cut)

2.0

1.5

1.0

0.5

0

80

120

160

200

Figure 24. Dry matter yields increase with longer intervals between cuttings whileforage quality rapidly declines, particularly during first and second cuttings.

Source: Adapted from Brink and Marten, University of Minnesota, 1989



n Soil fertility management is vitallyimportant for maintainingproductive alfalfa stands. Potas-sium (potash) is particularlyimportant for developing plantsthat have good winter survival.

n Greater harvest frequency andstand age at harvest increases thepotential for winter injury whenfall cuttings are taken. When theinterval between previous cuttingshas been 35 days or less, avoidharvesting during the critical fallperiod 6 weeks before the firstkilling frost (between September 1and October 15 in northern states,later in southern states). This allowsplants to enter winter with higherroot carbohydrates (figure 21).

n Young alfalfa stands survivewinters better than older standsdue to lower disease infestationand less physical damage.

n Stem and leaf stubble remainingin the late fall catch snow andinsulate the soil. Alfalfa harvestedin October should have a 6-inchstubble left and uncut strips toreduce risk of winter damage.

Making the decision to cut in the fallrequires using the above factors toestimate the risk of winter injury toalfalfa and weighing it against theneed for forage. The questions in table13 will help you assess the risk ofwinter injury.

52 _______________________________________________________________________________________________________________________________________________________ H A R V E S T ______________

Winter injury risk

If you score: Your risk is:3–7 low/below average

8–12 moderate/average

13–17 high/above average

>17 very high/dangerous

Table 13. Calculate your risk of alfalfa winter injury. Enter the score for answers thatdescribe your situation.

points score

1. What is your stand age?> 3 years 42–3 years 2≤ 1 year 1

2. Describe your alfalfa variety:a. What is the winterhardiness?

Higher than recommended for region 3Recommended for region 2Lower than recommended for region 1

a. total ___

b. What is the resistance to important diseases inyour region?No resistance 4Moderate or low resistance 3High level of resistance 1

b. total ___

Alfalfa variety total score (multiply a and b)

3. What is your soil pH?≤ 6.0 46.1–6.5 2≥ 6.6 0

4. What is your soil exchangeable K level?Low (≤ 80 ppm) 4Medium (81–120 ppm) 3Optimum (121–160 ppm) 1High (≥ 161 ppm) 0

5. What is your soil drainage?Poor (somewhat poorly drained) 3Medium (well to moderately well drained) 2Excellent (sandy soils) 1

6. What is your soil moisture during fall/winter?Medium to dry 0Wet 5

7. Describe your harvest frequency:Cut interval Last cuttinga

< 30 days Sept. 1–Oct. 15 5After Oct. 15 4Before Sept. 1 3

30–35 days Sept. 1–Oct. 15 4After Oct. 15 2Before Sept. 1 0

> 35 days Sept. 1–Oct. 15 2After Oct. 15 0Before Sept. 1 0

8. For a mid-September or late October cut, do you leave more than 6 inches of stubble?No 1

Yes 0

Determine your total score(sum of points from questions 1–8) total

Source: Adapted from C.C. Sheaffer, University of Minnesota, 1990a Dates listed are for northernmost states; states south of that area should use later dates.



53_______________________________________________________________________________________________________________________________________ E S T A B L I S H M E N T ________________

Harvesting the late-fall cutting willincrease tonnage for the season andmay be more profitable in areas whererisk potential is low (see table 13) andgood snow cover is likely and in areaswith less severe winters. Minnesotaresearch shows that taking a fourthcutting after October 15 is more prof-itable than three cuts by September 1(6 weeks before killing frost) or fourcuts by September 15 with no fallcutting for a 4-year-old alfalfa stand.In five-cut systems, the first cuttingyield the next spring was lowered byapproximately the same amount asthe yield from the fall cutting. Root rotwas increased and, therefore, standlife was also shortened.

Hay and silagemanagement

Hay-making and silage-makingdiffer in how the moisture content

of alfalfa is employed as a strategy inpreservation. Fresh alfalfa containsabout 80% moisture. Soluble sugarsand proteins are dissolved in theforage liquid. When concentratedthrough wilting, this “juice” providesan ideal medium for the growth ofyeasts, molds, and bacteria and forrapid activity of plant enzymes.Appropriate bacterial growth canresult in fermentation that produceslactic acid and preserves the materialas silage. When forage is dried to haybefore harvest, water in the forageevaporates, resulting in a higherconcentration of nutrients in theremaining liquid where cell growthand enzyme activity are restricted.

LossesEach step in the preservationprocess—mowing, raking, chopping,baling, storing, and unloading—causes a loss of forage dry matter(figure 25). Some losses result frommechanical action; others are biologi-cal processes. Total losses from cuttingto feeding are 20% to 30% of thestanding crop dry matter in typicalhay and silage systems. In hay-making, most of the losses result frommechanical handling and weatherdamage in the field. In silage-making,most losses occur during storage andfeed out.

Quality changesMost of the dry matter lost fromforage during harvest and storage hashigh nutritional value. More leavesthan stems are lost during hay-making, and most protein- andenergy-rich nutrients are concentratedin the leaves. Biological processes insilage-making use the most readilyavailable nutrients, such as plantsugars. Thus, in both hay and silagesystems, the changes that occur areoften detrimental to the quality of thefinal product.

Minimizing lossesDry matter losses and quality changescannot be eliminated in hay preserva-tion, but they can be minimized byusing good management practices.The practices for good hay-making aresummarized in table 14.

moisture when harvested (%)

dry

ma

tte

r lo

sse

s (%

)

80 60 5070 40 30 20 10

10

20

30

40

50

0

10

20

30

40

50

0

direct-cutsilage

wilted silage

plastic- wrapped bales

pre

serv

ati

ve-

tre

ate

d h

ay

storage lossharvest loss

field-curedhay

Figure 25. Dry matter losses during harvest and storage relative to foragemoisture content at harvest.

Source: Hoglund, Michigan State University, 1964



54

Quality losses during hay-making

n Respiration uses plant sugars, aprocess that increases NDF andADF and decreases digestibility.

n Rain on hay before baling leachessoluble nutrients (protein andcarbohydrates). NDF and ADFincrease; digestibility and crudeprotein decrease. Additionalquality is lost from leaf shattering.

n Rainy weather causes delays inharvest. NDF and ADF increase;digestibility and crude proteindecrease.

Good hay preservation dependsprimarily on handling and harvestmanagement. The drying rate,mechanical handling of the forage,and the moisture content at baling allaffect the quality of the hay. Withproper management, little or no dete-rioration takes place in the hay duringstorage.

Quality losses during silage-making

n Dry matter loss increases ADF andNDF; decreases digestibility anddry matter intake by animals.

n Loss of leaves decreases crudeprotein.

n Soluble protein can increase insilage during fermentation.Animals on high-performancediets (dairy or growing beef) needinsoluble protein, so performanceis lowered.

n Acid detergent fiber:crude proteinis protein made insoluble throughthe heating during fermentation.Up to 14% is beneficial; more than14% reduces protein availability tothe animal.

Unavoidable losses include those dueto field losses, plant respiration, andprimary fermentation. Avoidablelosses occur from effluent, anaerobicfermentation, and aerobic deteriora-tion in storage structure. Estimates ofunavoidable dry matter losses rangefrom 8% to 30%; avoidable lossesrange from 2% to 40% or higher. Theimportance of quickly achieving andmaintaining oxygen-free conditionshas led to improved equipment andtechniques for precision chopping,better compaction, rapid filling, andcomplete sealing.Alfalfa is more difficult than corn toferment properly because alfalfacontains fewer soluble carbohydratesrelative to protein. For an outline ofgood silage management practices seetable 15 on the next page.

_______________________________________________________________________________________________________________________________________________________ H A R V E S T ______________

Table 14. Summary of good hay-making practices.

practice reason benefit

mow forage early in day allow full day’s drying faster drop in moistureless respiration lossless likelihood of rain damage

form into wide swath increase drying rate faster drop in moistureless respiration lossless likelihood of rain damagehigher quantity and quality

rake at 40–50% increase drying rate faster drop in moisturemoisture content less respiration loss

less likelihood of rain damageless leaf shatterhigher quantity and quality

bale hay at 18–20% optimize preservation less leaf shattermoisture content inhibits molds and browning

low chance of firehigher quantity and quality

store hay under cover protect from rain, sun inhibits molds and browningless loss from rain damagehigher quantity and quality

Source: Pitt, Cornell University, 1991



Feeding considerations of hay and haylageA widely used rule of thumb informulating rations for lactating dairycattle is that one-third of the diet beforage, one-third concentrate, and theremaining one-third either forage orgrain, depending upon the quality ofthe forage fed. By feeding highquality alfalfa in place of lowerquality forages, dairy producers candecrease the amount of concentratesthat must be fed and can increase theutilization of forage. The lactationstudy in table 16 shows concentratescannot supply the energy required athigh production levels when thequality of the forage is too low.

How alfalfa is harvested andpreserved has been the focus of manyresearch studies, but no clear advan-tage in animal performance has beendemonstrated for harvesting andstoring alfalfa either as hay orhaylage. Harvesting alfalfa at highermoisture contents will decrease fieldlosses but will increase storage lossesunless forage is kept in airtight silosor silage tubes.

55_______________________________________________________________________________________________________________________________________ E S T A B L I S H M E N T ________________

Table 16. Fat-corrected milk (FCM) yield as influenced by change in alfalfamaturity and concentrate level.

concentrate in ration ———— alfalfa maturity (bloom) ————(% dry matter) pre early mid full

————— lb 4% FCM/cow per day —————

20 79.6 68.0 57.2 52.1

37 83.2 69.1 62.5 55.4

54 87.1 77.2 66.2 64.7

71 86.0 77.2 64.7 69.5

Source: Adapted from Jorgensen, University of Wisconsin, 1987

Table 15. Summary of good alfalfa silage practices.

practice reason benefit

minimize drying time reduce respiration reduced nutrient and energy lossesmore sugar for fermentationlower silage pH

chop at correct TLCa minimize exposure to oxygen reduced nutrient and energy lossesfill silo quickly more sugar for fermentationenhance compaction reduced silo temperaturesseal silo carefully less heat damage (browning)

faster pH declinebetter aerobic stabilityless chance of listerialess protein solubilization

ensile at 30–50% optimize fermentation reduced nutrient and energy lossesdry matter content proper silo temperatures

less heat damage (browning)control clostridiaprevent effluent flow

leave silo sealed for at allow complete fermentation lower silage pHleast 14 days more fermentation acids

better aerobic stabilityless chance of listeria

unload 2–6 inches/day stay ahead of spoilage limit aerobic deteriorationkeep surface smooth

discard deteriorated silage avoid animal health problems prevent toxic poisoning, mycotic infections prevent listeriosis, clostridial toxins

Source: Pitt, R.E., Cornell University, 1990aTLC = theoretical length of cut. Chop alfalfa silage at 3⁄8-inch TLC..



56 _______________________________________________________________________________________________________________________________________________________ H A R V E S T ______________

Advanced techniquesDrying agents, preservatives, andsilage inoculants

To speed drying, use a drying agent in

addition to mechanical conditioning.

These products, either sodium or

potassium carbonate, should be applied to

alfalfa as it is cut. They will shorten drying

time by 5 to 24 hours. Drying agents do

not work on grasses. These products cost

$2 to $6 per acre and require large

volumes of water for application.

Preservatives allow hay to be baled at

higher moisture contents than can

normally be stored: above 14% for bales

larger than 31⁄2' x 31⁄2'; 16% for 21⁄2' to 31⁄2'

square bales or round bales; and 20% for

small square bales. These products are

only cost effective if their use prevents rain

damage. So apply only when rain is immi-

nent. Propionic acid is the most effective

chemical preservative. Ammonium propi-

onate is less caustic than propionic acid

and equally as effective per unit of propi-

onate. Acetic acid is only half as effective

as propionic acid as a preservative. In all

cases the amount needed for preservation

is in relation to the moisture content of the

hay (figure 26).

Silage inoculants provide the lactic acid-

forming bacteria required for good haylage

or silage fermentation. These products

(either microbial or enzyme formulations)

are beneficial when naturally occurring

populations of lactic acid-forming bacteria

are low and plant carbohydrate levels high.

In the northern United States, these condi-

tions occur on all early- and late-season

cuttings when the drying time has been

less than 2 days (figure 27). Bacterial inoc-

ulants must be stored in cool places and

contain 106 Lacto-bacillus plantarum

colony forming units (cfu) per gram. To be

effective, the inoculant must be uniformly

mixed throughout the forage. A liquid appli-

cator on the chopper or on the blower is

the preferred method of application.

Figure 26. Propionic acid needed to preserve hay.

Source: Undersander, University of Wisconsin, 1999

Figure 27. Conditions for profitable use of inoculant onsilage. Shaded areas indicate profitable conditions.

Source: Adapted from Muck, USDA, 1993.

ave

rag

e a

ir t

em

pe

ratu

re (

°F)

forage moisture content at ensiling(% wet basis)

60

70

80

90

50

60

70

80

90

50

60

70

50

40 50 5545 60 65 70 75

40 50 5545 60 65 70 75

50 5545 60 65 70 75

1-day wilt

3-day wilt

2-day wilt

40

10

pro

pio

nic

ac

id r

eq

uir

ed

(lb

/ton

dry

mat

ter)

5

15

20

25

0

moisture content of hay (%)

1816 20 22 24 26

treat bales > 1500 lb

treat bales > 200 lb

treat small square bales



57_______________________________________________________________________________________________________________________________________ E S T A B L I S H M E N T ________________

Forage quality termsAcid detergent fiber (ADF) is the

percentage of highly indigestible and

slowly digestible material in a feed or

forage. This fraction includes cellulose,

lignin, pectin, and ash. Lower ADF indi-

cates a more digestible forage and is

more desirable.

Neutral detergent fiber (NDF) is the

percentage of cell walls or fiber in a feed. It

includes acid detergent fiber (except pectin)

and hemicellulose. NDF is inversely related

to animal intake potential: lower NDF

percentages indicate greater animal

consumption. Thus, a low percentage is

desirable as long as a certain minimum

fiber level in the ration is met.

Relative feed value (RFV) is an index

used to rank forages by potential intake of

digestible dry matter. The index ranks

forages relative to the digestible dry

matter intake of full bloom alfalfa (assum-

ing 41% ADF and 53% NDF at full

blooms).

Relative feed value (RFV) calculations

1) Calculate digestible dry matter offorage (% of dry matter)

DDM = 88.9 – (0.779 x ADF)

2) Calculate dry matter intake of forage (% of body weight)

DMI = 120 ÷ NDF

3) Calculate relative feed value

RFV = (DDM x DMI) ÷ 1.29

Crude protein (CP) is a mixture of true

protein and nonprotein nitrogen. It is

determined by measuring total nitrogen

and multiplying this number by 6.25.

Crude protein content indicates the capac-

ity of the feed to meet an animal’s protein

needs. Generally, moderate to high CP is

desirable since this reduces the need for

supplemental protein. Forage cut early or

with a high percentage of leaves has a

high CP content.



58 ________________________________________________________________________ A L F A L F A M A N A G E M E N T G U I D E









NCR547 Alfalfa Management Guide October 2004



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