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IV. Losses during Forage Conservation, Storage, and Handling

IV. Losses during Forage Conservation, Storage, and Handling

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418



ANDY D. MACDONALD AND E. ANN CLARK



The magnitude of these losses in yield and quality of forage during drying

and haymaking underscores the inherent conflict between managing for loss

of water while striving to retain yield and quality. Losses of dry matter and

nutrients in the conservation process may be considered in three phases:

respiratory and weathering losses during drying; harvest losses associated

with cutting, conditioning, raking, tedding, and baling; and storage and

handling losses.

A.



RESPIRATORY AND WEATHERING



LOSSES



Plant and microbial respiration throughout field drying can reduce

harvested yield by 2-8% under good drying conditions and by 16% under

poor conditions (Klinner and Shepperson, 1975). When drying is delayed by

extremely wet and humid conditions, as much as 30% of initial DM can be

lost due to respiration (Rees, 1982). Tullberg (1975) suggested that respiration losses in bulk samples of alfalfa can reach a maximum of 4% DM loss

per day, independent of plant maturity. However, photosynthesis may also

continue after cutting, partially offsetting respiratory losses (Greenhill,

1959).



Following cutting, plant respiration continues, but at a declining rate

(Wood and Parker, 1971) -until plant moisture content reaches about

3 0 4 % (May-Brown and Harris, 1974; Martin, 1980; and others cited in

Klinner and Shepperson, 1975). Even when whole plant moisture content

has reached 30-40%, the slower-drying parts of the plant will continue to

respire until they too reach that point (Rees, 1982). Rewetting due to dew or

rainfall prolongs respiration and increases overall loss. Using thin-layer drying, Simpson (1961) found that crushing forage stems stimulated respiration, but as crushing also accelerated drying and caused respiration to cease

earlier, overall respiration losses were reduced.

Protracted field drying exposes hay to potential leaching and weathering

losses, which can significantly reduce not simply DM but also digestibility

of the conserved forage. Leaching of soluble nutrients from the cut plant

material is the principal component of weathering damage, followed by leaf

and bloom loss and molding (Hill, 1976). Timing of rainfall is perhaps more

critical than amount, as tolerance to rainfall declines with drying time. The

relative integrity of the cuticle and cellular membranes in fresh-cut forage

prevents loss of soluble nutrients such as nonstructural carbohydrates and

potassium (Murdock and Bare, 1963).

Loss of digestibility, amounting to 5 percentage units or more of digestible organic matter (Nash, 1978), and decreased voluntary intake can accompany even modest rainfall. In 21 comparisons between grass hays which

were field-cured with and without rainfall damage, Wilkinson (1981)



WATER AND QUALITY LOSS DURING DRYING OF HAY



419



reported a decrease in digestible DM intake of 8 percentage units. Following

rainfall ranging from 25 to 38 mm on grass and grass-legume hay, DM intake was reduced by 5 and 20 g/kg0.75,respectively, and DM digestibility

was reduced by 4 and 8.8 percentage units, respectively (Milligan, L. P.,

Mathison, G. W., Weisenberger, R. D., and Kennedy, P. M. 1981. Forage

damage-effects on feeding value. Univ. of Alberta. Unpublished mimeo).

Incorporating both effects, digestible DM intake was reduced, on average,

by 12% and 30% in the grass and grass-legume hays, respectively.

Collins (1983) reported that susceptibility to weathering-induced reductions in DM and quality varied between alfalfa and red clover, and also with

the timing and duration of wetting. Simulated rainfall of 2.5 cm applied

after 24 hr of field drying increased mean DM loss from 8.1% for the

unwetted control to 17% and as much as 25.8% for red clover cut at first

flower. Rainfall of 4.1 cm over a 4-day period increased mean DM loss

from 10.5% for the control to 43.4%, with concomitant reductions in in

vitro DM digestibility (IVDMD) from 66.4 to 48.1%. Reductions in total

nonstructural carbohydrates were greater than those of N or IVDMD. Collins (1983) reviewed literature suggesting that legumes are more sensitive to

weathering damage than are grasses.



B. HARVESTING

LOSSES

Losses of dry matter and nutritional value during drying and baling depend on the type of mower used for cutting, on the postcutting or conditioning treatment, on timing and method of raking and tedding, and on the

type of baler and hay moisture content at harvest (Klinner and Shepperson,

1975).

1. Mowing



a. Equipment. The process of cutting or mowing a standing crop of

forage may be accomplished with a variety of implements, some of which

are self-propelled, while others are pulled behind or beside a tractor. Cutting width of these units is fixed, typically ranging from 2.0 to 4.2 m, a

characteristic which influences not simply the number of passes needed to

cut a field, but also the density of the resulting windrow. Concentrating

forage from a 4.2-m cutting width into a l-m windrow results in a heavier,

more compactible windrow than does that from a 2.0-m cutting width.

Unlike cutting width, cutting height is adjustable on all units and typically ranges from 5 to 10 cm aboveground. Cutting height influences stubble

height, which in turn, influences soil contact and boundary layer resistance

(see Section IlI,C,l). In addition, height of cutting affects both yield and



420



ANDY D. MACDONALD AND E. ANN CLARK



quality of harvested forage. Taylor and Rudman (1965) reported an

11-15% reduction in growth rate of steers when offered grass hay cut at 6.5

versus 10 cm aboveground, presumably due to a greater contribution of

older stem tissue in the lower cut forage.

The term swather is often used to mean a self-propelled device which simply

cuts and lays down forage either in a swath or in a windrow, and as such, may

serve a dual purpose for cutting small grains or rapeseed (Brassicasp.). A

subsequent improvement was the mower-conditioner (m/c), which is either

self-propelled or pulled behind a tractor. As the name implies, the m/c conditions (see Section IV,B,2), as well as cuts the forage. The cutting action for

both the swather and the m/c is typically provided by a reciprocating, linear

cutter bar, which relies on the rapid lateral motion of a toothed knife against a

stationary guard to cut standing forage. Newer m/cs can also be fitted with

disk-type rotary mowers instead of the traditional cutter bar.

The cutting action in a flail-type mower relies on a series of freeswinging,

hardened steel flails, which are attached to a rapidly spinning central

cylinder oriented parallel to the ground. Flail-type mowers lacerate and

chop the cut forage into 10- to 20-cm lengths, which has the useful effect of

thoroughly mixing old with young plant parts, reducing selective feeding by

steers (Taylor and Rudman, 1965).

A more recent innovation is the rotary mower, which appears to be

replacing the cutter-bar mower, especially in Europe. Rotary mowers use a

system of rotating disks or drums with pivoting knife sections to replace the

reciprocating knife of the conventional cutter-bar mower.

b. Losses. Klinner (1975) showed that DM losses were slightly less when

hay was cut with a reciprocating or cutter-bar mower than with a rotary

mower, possibly due to the greater physical damage inflicted on plant

tissues by repeated, high-speed contact during rotary mowing. Results cited

in Svensson (1978) were consistent with those of Klinner (1975), and it was

further noted that a flail-type mower caused considerably more DM loss

than did a rotary mower, again due to repeated laceration of the crop.

Svensson (1978) reported that DM losses were 5-20% for a conventional

cutter-bar mower, 5-25% for a rotary mower, and 1540% for a flail-type

mower when all machines were operated at a typical operating speed of 6.1

km/hr.

Von Bargen (1978) measured slightly higher DM losses with a rotary

mower than with a conventional cutter-bar mower when both were operated

at 6.4 km/hr. When travel speed was increased by 50%, however, DM loss

increased with the cutter-bar mower but was unaffected with the rotary

mower. Reducing the flail speed or increasing the forward speed of flailtype mowers may decrease yield in heavy crops due to an increase in stubble

height. Effective stubble height is increased because the flails push the

material over, making contact higher on the stem. At the same time,



WATER AND QUALITY LOSS DURING DRYING OF HAY



42 1



however, DM losses are reduced with a lessening of flail speed or an increase in travel speed because of concomitant reductions in laceration of

plant material.

The primary advantage of rotary mowers lies in their ability to handle

heavily fertilized or lodged forage and to avoid stone damage, thus requiring less frequent repairs. Because of these advantages, Klinner and Shepperson (1975) found that the newer horizontial rotary mowers of the disk and

drum type were replacing cutter-bar mowers in Great Britain, despite their

higher cost and slightly higher tractor power requirement.

Clothier and Taylor (1980) compared drying time of a perennial ryegrass

and white clover mixture cut by disk- versus drum-type rotary mowers, both

with and without conditioning treatments. When unconditioned, drying

was faster in swaths cut with the disk- than with the drum-type mower.

When conditioned, drying time to safe baling moisture was unaffected by

mower type. Differences in swath architecture, with that produced by the disktype mower having a lower bulk density, could encourage faster drying in

windrows cut by a disk- compared to a drum-type rotary mower (Clothier

and Taylor, 1980).

2. Mechanical Conditioning



Klinner and Shepperson (1975) define crop conditioning as a mechanical

or chemical action designed to increase the rate of evaporation of crop

moisture. In practice, mechanical conditioning reduces cuticular resistance

to water loss by crushing or crimping (Greenhill, 1959; Clothier and Taylor,

1980) or by surface abrasion (Klinner and Hale, 1980). In addition, the process of propelling the conditioned forage backwards from the rollers, such

that it strikes the apron and is shaped into a windrow by the adjustable baffles, produces an open and airy structure, which minimizes boundary layer

resistance.

Conditioning is typically accomplished at the same time as mowing, often

using the same machine. The equipment which is used to condition by

crushing is termed a mower-conditioner or haybine. Crushing is a process

by which plant material is pulled through a pair of solid, high-speed, metalor rubber-coated rollers, often of an intermeshing herringbone design,

which split or damage the stem longitudinally. Conditioning by crimping

uses a device called a crimper, which is similar to a m/c, except that the

open rather than solid rollers cause the cuticle to be broken laterally. Surface abrasion differs from crushing in that the waxy cuticle of the leaves and

stems is modified or damaged, typically with tufted brushes, but the stem

itself is not split open. Abrasion is caused by unequal brush speed as the

plant material passes between opposing rollers.



422



ANDY D. MACDONALD AND E. ANN CLARK



Under good drying weather, conditioning may increase drying rate by as

much as 75% during the initial stages of drying (Dernedde, 1980), with a

lesser effect in later stages. First-cut crops, which tend to be thicker stemmed,

often respond well to mechanical conditioning, while the finer stems

characteristic of later cuts may pass through the conditioner more or less untreated. The benefit of conditioning may not be observed if the drying environment is poor or the windrow is heavy (Crump, 1985) and is usually more

apparent on legume than on grass crops, as shown by Ciotti and Cavallero

(1980). They found that rate of moisture loss in orchardgrass (0.34%

moisture per saturation deficit hour) (SDH) was unaffected by conditioning,

while that of alfalfa increased from 0.19 to 0.27% per SDH.

The main advantage of surface abrasion over crushing or crimping is that

the structural integrity of the windrow remains intact, leaving the windrow

more resistant to compaction. A weakly structured windrow will constitute

greater boundary layer resistance, thus retarding outward passage of water

evaporating from the inner plant tissues. Dernedde (1980) compared drying

patterns in forage cut with a two-drum mower and then conditioned by

either crushing with a m/c or by surface abrasion with a tedder (see Section

IV,B,4). Conditioning by crushing weakened stem strength, which promoted windrow collapse and slower drying. Conversely, while tedding

tended to leave a light and fluffy windrow, it was not possible to vary the

degree of abrasion applied, resulting in excessive leaf shattering. Equipment

described by Klinner and Hale (1980) used tufted or solid plastic rotary

brushes instead of metal or rubber rollers to condition the crop, which

reduced total power requirement by 25% compared to a metal spoke rotor,

and achieved similar drying rates (Klinner and Hale, 1980).

Mechanical conditioning has been reported to increase leaching losses if

the cut hay is subjected to rainfall during the drying cycle (Von Bargen,

1978; cited in Harris and Tullberg, 1980). Both increased microbial

degradation and shattering losses during subsequent raking, baling, or

handling have also been associated with conditioning (Martin, 1980).

However, overall DM losses in conditioned hay are typically less than in unconditioned hay because the risk of additional leaching and shattering losses

is more than offset by decreased drying time, which reduces respiration and

weathering losses (Murdock and Bare, 1963).

3.



Chemical Conditioning



Chemical conditioning refers to the use of chemical agents which

reportedly alter cuticular resistance and thus enhance drying rate. Faster

drying improves both yield and quality of hay by reducing duration of

respiratory losses, lessening the risk of weathering damage, and hastening

hay removal, which encourages faster regrowth. Paraquat, a bipyridyl



WATER AND QUALITY LOSS DURING DRYING OF HAY



423



herbicide, (Arnold and Barrett, 1978), potassium carbonate (K,CO,)

(Tullberg and Angus, 1972; Clark et al., 1985; Rotz and Davis, 1986a,b;

Crump, 1985), methyl esters (Wieghart et al., 1983), and various other

chemicals reviewed in Harris and Tullberg (1980) have been tested as potential drying agents. Concerns about chemical conditioners typically involve

(1) possible side effects on animal acceptability (2) the excessive amounts of

water required to carry and disperse the product, and (3) nonuniformity of

application. The effect of chemical conditioners on animal intake is product

specific and needs further testing.

Early work with K,CO, involved application rates as high as 400-800

literslha (Tullberg and Minson, 1978; Wieghart et al., 1983), a volume of

water which constitutes either significant additional weight or frequent tank

refilling. Reducing application rate to more feasible volumes of 150-300

literdha, as recommended for some of the newer products, reduced product effectiveness (Rotz and Davis, 1986a). When higher concentrations of

the active ingredients, modifications in pump pressure, and changes in nozzle type failed to compensate for lesser application rates, it was concluded

that high carrier volumes may be necessary for effective performance.

Uneven coverage of fresh-cut forage by either liquid or powder formulations, due to both variation in windrow density and applicator malfunction,

creates pockets of overly moist hay in an otherwise dry bale. Windrow density varied by a factor of 3.4:l in a trial at a British research station,

although 99% of the variation was within f 15% of the mean (Charlick et

al., 1980). In the same trial, 95% of the variation in moisture content was

within *2Vo of the mean, a factor of critical importance when application

rate varies with moisture content of the forage. The resulting heterogeneity

in bale moisture, which would probably be larger under farm conditions,

creates pockets of mold which can spread outward, causing unacceptable

variation in hay quality within and among bales.

Solution of this problem will await improvements in applicator design

and methodology (Klinner and Holden, 1978; Charlick et al., 1980; Rotz

and Davis, 1986a). For example, K2C03solutions were found to work most

consistently when applied in conjunction with a roll-type conditioner, in

part because the rollers distributed the chemical more uniformly as the

forage passed through (Rotz and Davis, 1986a). However, variations in

nozzle type, including flat-fan, hollow-cone, and solid-cone nozzles, at both

high and low pump pressure did not influence drying rate.

Solutions of K,CO, have been found to accelerate legume drying under

both single-layer conditions (Tullberg and Angus, 1972; Crump, 1985) and

in the field in Australia (Tullberg and Minson, 1978), in Michigan (Rotz and

Davis, 1986b), and in Alberta (Crump, 1985). Because drying rate is

enhanced more in stems than in leaves, K,CO,-treated stems can reach safe

baling moisture before leaves overdry and shatter, thus improving the



424



ANDY D. MACDONALD AND E. ANN CLARK



leafistem ratio and overall quality, as well as yield (Tullberg and Minson,

1978). The quantities of potassium added to hay by applying K2C03as a

chemical conditioner are so low that it is unlikely to influence nutritive

value (Tullberg and Minson, 1978).

K2C03reportedly acts by modifying the wax platelet structure of the cuticle, thus permitting water loss via a continuous liquid film from inner to

outer surfaces, as discussed in Harris and Tullberg (1980). KzC03reduced

drying time by 42-57070 in a study with alfalfa, sweetclover, sainfoin, alsike

clover, and red clover (Clark et al., 1985). All legumes responded to treatment, but species differed in degree of response, with sweetclover drying

rate most affected by the product. Chung and Verma (1986) demonstrated

that K2C03was ineffective with grasses. Weighart et al. (1983) reported an

additional enhancement in drying rate when KzC03 was combined with

methyl esters and a surfactant, although subsequent tests have focused

primarily on KzC03(Rotz and Davis, 1986a,b).

Harris et al. (1974) indicated that a combination of both mechanical

damage and thermal or chemical surface treatment could form the basis for

more effective methods of increasing the drying rate of field crops cut for

conservation. In a study conducted in Alberta, Crump (1985) reported that

combining mechanical and chemical (K2C03)conditioning significantly increased drying rate over KzC03 alone in three of five trials, and over

mechanical conditioning alone in two of five trials. She concluded that the effects of mechanical and chemical conditioning may be partly additive or that

the distribution of the product was improved by passing through the rollers.

Rotz and Davis (1986b) studied the effect of mechanical (intermeshing

rubber rollers) and chemical (K2C03)conditioning treatments alone and in

combination on an alfalfa hay crop. While mechanical conditioning increased the drying rate of first-cut alfalfa only, chemical conditioning improved the rate in all cuts, provided that drying conditions were favorable.

When combined, the two treatments slightly increased drying rate of firstcut alfalfa over that which was mechanically conditioned, and in subsequent cuts, over that which was chemically conditioned. Field losses were

not significantly changed by treatment.

4. Raking and Tedding



Tedders and rakes are used to open up the windrow, which promotes drying by increasing airflow and enhancing penetration of radiant energy into

the windrow. As observed by Fitzherbert (1523, quoted by Nash, 1978),

". . . good teddying is the chief poynte to make good hay. . . ." Rakes are

also used to invert windrows following rainfall, to expose the moist underside to better drying conditions, or to collect a loose swath and place it in a

windrow prior to baling.



WATER AND QUALITY LOSS DURING DRYING OF HAY



425



A properly made windrow has the small-stemmed, quick-drying, leafy

portions of the plant surrounded by the coarse-stemmed, slow-drying part

of the plant. Because leaves dry faster than stems, arraying tissues in this

order exposes the slow-drying stems to the most favorable drying environment, thus encouraging a more uniform drying of the hay crop (but see also

Pedersen and Buchele, 1960). Proper and careful raking can contribute to

optimal windrow architecture.

The windrow produced by most mowers is compact and lumpy, and as

windrow resistance is initially the primary limiting factor, drying rate increases following tedding early in the drying cycle down to a moisture content of 50%, with subsequent raking and turning (Nash, 1978). Because of

damage to stem strength caused by mechanical conditioning, the windrow

often compresses under its own weight, thus requiring periodic tedding to

keep it open. Frequent disturbance ensures maximal ventilation, particularly to the innermost and underlying parts of the windrow profile (Clark and

McDonald, 1977). Jones and Harris (1980) also noted that tedding serves to

mix layers within the windrow resulting in more uniform drying.

Tedding is seen with lesser frequency in North America than in Europe,

perhaps because top quality hays are predominantly composed of grasses in

Europe, while the focus is on legumes in North America. Grasses are less

vulnerable to leaf loss and can thus tolerate greater agitation during the drying cycle (Nash, 1978). Native grass hay lost 10-15% DM, while

grass-alfalfa hay lost 15-25 %, when raked at similar moisture contents

(Friesen, 1978). Wilkinson (1981) reported average losses between cutting

and baling in hay subjected to four postcutting treatments as 38.9% for

alfalfa but only 19.1% for grass. Frequency and timing of tedding relative

to moisture content strongly influence potential DM losses. Murdock and

Bare (1963) found that tedding the same day as cutting resulted in a greater

yield and faster drying than did tedding 1-2 days after cutting. Jones and

Harris (1980) reported that tedding was most beneficial to drying in the

range of 67-50010 moisture, after which plant resistances dominate.

Tedding may also be more suited to immature than to' mature tissues.

Dexter (1947) and Wilman and Owen (1982) observed that immature, leafy

material tends to pack down into the swath to a greater extent than does

more mature, stemmy material, such that tedding is more appropriate on

juvenile than on mature forage.

The more vigorous action of tedders is designed for use early in the drying

cycle, when the forage is moist and relatively insensitive to agitation. When

it is necessary to disturb drier material, the gentler rake is preferred. The two

most common types of rakes are the side-delivery rake and the finger-wheel

rake. The conventional side-delivery rake uses an angled, tine-spring tooth

beater, oriented parallel to the ground, to gather or turn a windrow. The

finger-wheel rake consists of several large, ground-driven spring-toothed



426



ANDY D. MACDONALD AND E. ANN CLARK



wheels, oriented perpendicular to the ground, which roll the hay to one side

to form a windrow.

Dry matter losses may occur as a result of raking or turning a hay crop,

with the magnitude of loss depending on the type of rake, the moisture content at raking, and the yield and species composition of the hay. DM losses

ranged from 5 to 11% for a side-delivery rake and 0-12070 for a fingerwheel rake, with lowest losses occurring when raked above 40% moisture,

and highest losses occurring when raked at 28% moisture (cited in Friesen,

1978). Dobie et al. (1963) reported that raking hay at 10-15'70 moisture

reduced yield and nutritional value by 25 and 30%, respectively, when compared to raking at 40-50% moisture. A short, light crop raked at low

moisture content is most vulnerable to raking losses.



5. Baling



a. Equipment. Balers harvest and package dry hay into managable units

for transport, storage, and feeding. The shape, size, and weight of bale

packages varies among balers, from the conventional square or rectangular

bales to large round bales (LRBs) (Table I). Hay may also be packaged in

cubes, in large rectangular bales weighing up to 0.9 tons, and in hay stacks

or loaves weighing up to 7 tons (Larsen and Rider, 1985).

The various large bale packages have become increasingly popular

because they substitute mechanical energy for human labor, a direction

which many have perceived as cost effective. However, the size and weight

of the various large package systems imply complementary investment in

specialized equipment to retrieve the bales from the field and feed them to

Table I

Descriptive Statistics on Hay Packaging Systems



Package

Bales

Conventional

Largeround

Large

rectangular



Dimensions (cm)



Density

(Wm')



36 x 46 x variable



160-300



100-170 x 100-180

122 x 122 x 200-280



110-250

240



Stacks



260-750 x 210-360 x 240-520



Cubes

Pellets



4 X 4 X 5



400



0.5 x 2.5 x 2.5-4.5



550



55-95



Source

Friesen (1978)

Larsen and Rider (1985)

Larsen and Rider (1985)

Larsen and Rider (1985)

Friesen (1978)

Nash (1978)

Larsen and Rider (1985)



WATER AND QUALITY LOSS DURING DRYING OF HAY



427



livestock. Lechtenberg (1978) noted that large hay packages require

specialized feeding management to lessen feeding waste. As such, he emphasized that the labor and mechanization advantages of the large bale

packages must be reconciled with greater potential feeding and storage

losses.

Labor efficiencies are considered to be the basis for the popularity of

LRBs, with average handling rates of about 2.5 to 5.6 tons/manhour

(Friesen, 1978; Kjelgaard et al., 1981; Heslop and Bilanski, 1986). Particularly with restricted labor availability, the possibility of baling without

hired help is considered a bonus on many contemporary farms. However, as

noted by Von Bargen (1978), careful management is required to ensure that

the quality of LRB hay equals that of conventional square bales.

Although conventional bales are vulnerable to weathering, and thus, require cover for storage, they do allow for the greater freedom in utilization,

because they are light enough to be moved manually and can be fed either

mechanically or manually (Larsen and Rider, 1985). Self-propelled bale

wagons have been designed to recover bales from the field mechanically and

to transport them to a storage area. Bale throwers or ejectors are an increasingly popular addition to many conventional balers because they reduce

conventional baling to a one-person, one-pass operation, analogous to LRB

baling. Average handling rates for conventional bale packages are on the

order of 0.8-2.1 tons/manhour (Friesen, 1978; Kjelgaard et al., 1981).

6. Losses. Losses of DM at baling may occur at pickup or in the bale

chamber itself and are affected by moisture content, by species composition, and by type of baler. Excessive moisture at baling permits microbial

activity, which engenders potential bale heating, respiratory losses of carbon dioxide, changes in chemical composition, and decreases in digestibility

of protein and energy. At the other extreme, hay which has overdried prior

to baling is subject to higher DM and nutrient losses at baling (Dobie et al.,

1963). Friesen (1978) reported the practice of baling dry hay at night, after

dewfall, to reduce baling losses.

Conventional rectangular baling incurs losses ranging from 3 to 8070,

while losses associated with baling as LRBs range from 1 to 15% (cited in

Martin, 1980). The Prairie Agricultural Machinery Institute (P.A.M.I.,

1977) indicated that bale chamber losses from large round balers could be

reduced by baling conditioned hay and traveling at the fastest possible

ground speed while baling. In addition, increasing the cutting width and

reducing power takeoff speed when harvesting light crops can reduce bale

chamber losses (P.A.M.I., 1977). Kjelgaard et al. (1981) found that baling

losses decreased when windrows were combined before baling, although the

process of raking windrows together increased losses before baling to the

point at which there was little if any benefit.

Baling losses vary with species and with plant maturity. Shepherd (1959)



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ANDY D. MACDONALD AND E. ANN CLARK



found that susceptibility of alfalfa, white clover, and subterranean clover

(T. subterranean L.) leaves to shattering loss was least when plants were

harvested at a juvenile stage and increased with both plant maturity and

time in the season. Nash (1978)concluded that leaf shattering in alfalfa,

even under favorable conditions, accounted for losses of 15% of total crop

weight, and up to 3045% of total weight under poor conditions.



c.



STORAGE AND HANDLING

LOSSES



Losses occurring during transport from the field to storage area, from

microbial activity in storage, and from processing to feeding can reduce the

quantity and quality of conserved feed. Friesen (1978)reported that DM

losses during transport alone can vary from 1 to lo%, depending on the

type of crop, the length of time the bales had been left in the field, and the

type of pickup used.

1. Storage



The source and magnitude of storage losses will depend on moisture content at baling and whether the dry hay is stored with or without cover. Hay

stored at 20% moisture should lose no more than 5% DM due to respiration, although DM losses for hay stored at 25010 moisture can reach 10'70,

and hay baled at 35-40% moisture will lose 15-20'70 DM due to respiration

(Nash, 1978). Storage losses of CP in alfalfa varied from 17.9 to 29.2070,

respectively, for LRBs stored in the barn versus outdoors without cover

(Heslop and Bilanski, 1986). Equivalent losses of digestible DM were 4.2

and 23.4'70,respectively. Losses of DM in storage ranging from 8 to 32%

have been observed when large hay packages were stored outside

(Lechtenberg, 1978). Losses specific to outside storage are due to weathering around the bale exterior, particularly where bales touch each other or

the soil.

a. Losses Due to Excessive Moisture at Baling. Hay that is cut at proper

maturity, dried quickly in the field, baled at safe baling moisture content,

and stored indoors is green, leafy, and shows no mold growth (Miller et al.,

1967; Martin, 1980). However, if hay is baled in excess of safe baling

moisture, often under pressure of unfavorable weather, molding begins and

hay color deteriorates to gray or brown. Because the criteria most

associated with top quality hay include bright green color, a high 1eaf:stem

ratio, and freedom from the odor and dustiness indicative of mold growth,

these organoleptic or sensory changes in hay quality can markedly affect its

real and perceived nutritional value.

Hay baled at a moisture content above about 20% deteriorates during



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