From Pasture Management Guide
Growth
Dry weight accumulation
Growth follows a sigmoid curve
Harvest
Time increasing
Detergent Procedure to Partition Forages
Forage
Digest with neutral detergent
soluble
Cell Contents
proteins
starch
sugars
organic acids
pectin
insoluble
Hemicellulose, Cellulose, Lignin
(NDF)
Digest with acid detergent
soluble
Hemicellulose
insoluble
Cellulose and Lignin
(ADF)
Digest with 72% sulfuric acid
soluble
Cellulose
insoluble
Lignin ADL
Fig. 16.7. Digestibility ranges of major forage types. Dashed lines illustrate
forage digestibility levels needed to meet energy requirements of different classes
of beef cattle (Riewe, 1981 and Reid et al., 1988). From Forages Vol. I, An
Introduction to Grassland Agriculture, 6th ed.
Stage of Maturation:
Fig. 16.8. Maturity effects on alfalfa quality. From Forages Vol. I,
An Introduction to Grassland Agriculture, 6th ed.
Leaves vs Stems
Fig. 16.6. Forage quality analysis of leaf and stem tissue from alfalfa and
timothy growing together in a mixture (Collins, 1988). From Forages Vol. I, An
Introduction to Grassland Agriculture, 6th ed.
Forages Vol. I, An Introduction to Grassland Agriculture, 6th ed.
When K increases, winter survival increases.
When N increases, winter survival decreases.
Forages Vol. I, An Introduction to Grassland Agriculture, 6th ed.
Introduction to Forages
V.G. Allen, C. Batello, E.J. Berretta, J. Hodgson,
M. Kothmann, X. Li, J. McIvor, J. Milne, C. Morris,
A. Peeters, M. Sanderson. 2011. An international
terminology for grazing lands and grazing
animals. Grass and Forage Sci. 66: 2-28
DOI: 10.1111/j.1365-2494.2010.00780.
What is “forage”?
•
•
Pastureland
land devoted to the production of indigenous or
introduced forage for harvest primarily grazing.
Pastureland generally must be managed to
arrest successional processes.
Rangeland
land on which the indigenous vegetation is
predominately grasses, grass-like plants, forbs,
or shrubs and is managed as a natural
ecosystem. Often a semi-arid region. If plants
are introduced, they are managed as
indigenous species.
What is “forage”?
Forage - edible parts of plants, other than
separated grain, generally above ground, that can
provide feed for grazing animals, or can be
harvested for feeding.
• Woody
• Herbaceous, “herbage” non-woody
• Grass - Poaceae family
• Grass-like - vegetation is similar to grass in
appearance; member of the Cyperaceae (sedges)
and Juncaceae (rushes) families
• Forb - any herbaceous broadleaf plant that
is not a grass or is not grass-like
• Legume - member of the Fabaceae family
• Non-legume
What is “forage”?
•
•
Pasture, animal harvest, grazing, harvested
plant material is 80% moisture
Hayfield, mechanical harvest, storage
• Silage/haylage - wet; wilted; chopped;
fermented, 60 - 40% moisture
• Hay - dry; wilted; baled, <20% moisture,
• Pellets - dehydrated; quickly dried at 3001000 C; ground; pellet or cube
What is “forage”?
•
•
•
Diverse plant material within a field;
diverse species: grasses, legumes,
forbs; diverse canopy heights; diverse
rooting depths; diverse maturations, i.e.
mimicing the prairie
Few plant species; a grass and a
legume species; diverse plant structure;
not diverse maturation
Monoculture; one species, often alfalfa
What is “forage”?
Annual: one year, harvested immature, typically
harvested for grain, for ex. small grain
haylage/silage, corn silage, sorghum silage,
sorghum-sudangrass silage
Biennials: Brassica spp, (turnips) grazed the
first year while vegetative
Perennials: multiple year life span
What is “forage”?
What does the consumer (animal) want?
• Maximum quantity, dry matter/feeding
• Maximum quality, nutritive value
The goal of the producer:
• Maximum quantity (yield), dry matter/A
• Maximum quality, nutritive value
• Stand persistence, perennial stand
remains healthy over years
From Pasture Management Guide
Seasonal growth patterns in forages
Species
Kentucky
bluegrass
Orchardgrass
Reed
Conarygrass
Alfalfa
Red clover
White clover
April
May
June
July
Aug.
Sept.
Oct.
Growth/Yield is a result of photosynthesis
•
•
•
Photosynthesis, capturing sunlight which used as
the energy to fix CO2, produce sugar, that is used
for growth, production of dry matter, yield
Green tissue captures sunlight, both leaves and
stems
Capturing sunlight so that no sunlight reaches the
soil surface, inhibiting low growing forages in a
mix, forage stand not reaching its potential
Growth
Dry weight accumulation
Growth follows a sigmoid curve
Harvest
Time increasing
Sugar production leads to dry matter
accumulation
Sugar
cell contents
fructan or starch
cell wall
Hemicellulose
Cellulose
Lignin
growth, excess is stored
structure
Defoliation – removal of foliation (harvest)
(leaves, stems)
Due to:
 Mechanical harvest
 Grazing
 Other organisms, animals, diseases
 Fire
 Chemicals, herbicides
 Extreme cold temperatures, winter
After defoliation:
• For one to two weeks, above ground
growth has priority
• Root growth stops, fine roots and root
hairs may die
• Nutrient uptake declines
• N-fixation is greatly reduced or ceases
Growth
Dry weight accumulation
Regrowth follows a sigmoid curve
Harvest regrowth
Defoliation
Time increasing
The ability to fully recover will depend upon:
 Availability and type of meristematic




tissue
Remaining leaf area
Carbohydrate reserves, nutrient levels
Frequency of defoliation
Environmental conditions
Remaining leaf area (LA)
• LA location of sugar production, the amount of
•
•
•
•
sugar produced is proportional to the leaf area,
sugar is needed for growth
Height of cutting or bite, the more LA the faster the
recovery, less the “yield”
For growth the plant uses CHO reserves: base of
the stem, crown, rhizomes, roots
Initial spring growth, no LA, CHO reserves only
The level of N in reserves influences initiation of
regrowth, amino acids are used
Frequency of defoliation
• As frequency of defoliation increases, the time
between harvest decreases
• Less regrowth has accumulated, lower yields
• The ability for CHO reserves to completely
replenish decreases
• Resulting in less yield, slower regrowth,
weakened plants, dead plants
Figure 2. Changes that occur in dry-matter yields and CHO
reserves during growth periods of an alfalfa crop.
Effect of harvest frequency on yield.
Harvest frequency
(weeks)
Yield
(ton/acre)
3
7.9
4
8.4
5
9.2
6
10.3
8
10.2
12
10.4
Growth
Dry weight accumulation
Regrowth follows a sigmoid curve
Harvest regrowth
In IA:
2.5 weeks, May-June
5+ weeks, Aug-Sept
Time increasing
What does the consumer (animal) want?
• Maximum quantity, dry matter/feeding
• Maximum quality, nutritive value
The goal of the producer:
• Maximum quantity (yield), dry matter/A
• Maximum quality, nutritive value
• Stand persistence, perennial stand
remains healthy over years
Amount of nutrients and the ability to get to the nutrients
(digestibility of the plant material)
Structural sugars
Sugar
cell contents
fructan or starch
cell wall
Hemicellulose
Cellulose
Lignin
Detergent Procedure to Partition Forages
Forage
Digest with neutral detergent
soluble
Cell Contents
proteins
starch
sugars
organic acids
pectin
insoluble
Hemicellulose, Cellulose, Lignin
(NDF)
Digest with acid detergent
soluble
Hemicellulose
insoluble
Cellulose and Lignin
(ADF)
Digest with 72% sulfuric acid
soluble
Cellulose
insoluble
Lignin ADL
Digestibility
•
Measured using bioassays
• In situ, or in vivo in the animal, using fistulated animals;
digestion trials, apparent dry matter digestibility, (DM
intake - DM out)/ DM intake
• In vitro, in test tube with rumen fluid, outside the animal,
IVDMD (in vitro dry matter disappearance)
• Calculated
• Total digestible nutrients (TDN), summation of the
digestibility of the different components
• DDM (digestible dry matter), DDM% = 88.9 - (0.779 x
ADF%)
Forage quality needs depend upon:
•
•
•
Animal species
Purpose or function of the the animal
• Lactation; greatest nutrient need
• Growth, meat; younger animals > older
Stage of development
• Growing, 1-1.5 maintenance
• Lactating, 2-2.5x maintenance
• Maintaining
Fig. 16.7. Digestibility ranges of major forage types. Dashed lines illustrate
forage digestibility levels needed to meet energy requirements of different classes
of beef cattle (Riewe, 1981 and Reid et al., 1988). From Forages Vol. I, An
Introduction to Grassland Agriculture, 6th ed.
Plant Species
•
•
•
•
Protein:
• legumes > cool season grasses > warm season
grasses
• N fertilization can increase CP in grasses.
Fiber:
• warm season grasses > cool season grasses >
legumes
Minerals: legumes > grasses
Varietal differences: not much selection is based on
quality; more on yield, stand persistence, pest
resistance
Stage of Maturation:
Fig. 16.8. Maturity effects on alfalfa quality. From Forages Vol. I,
An Introduction to Grassland Agriculture, 6th ed.
Stage of Maturation
•
Change in maturity:
• the rate of change is species dependent,
digestibility of grasses declines faster than the
digestibility of legumes
• quality of stems declines with age, quality of
leaves remain fairly constant
Leaves vs Stems
Fig. 16.6. Forage quality analysis of leaf and stem tissue from alfalfa and
timothy growing together in a mixture (Collins, 1988). From Forages Vol. I, An
Introduction to Grassland Agriculture, 6th ed.
Leaf:stem ratio
•
•
•
•
Amount of DM from the leaf portion of the forage
compared to the amount of DM from the stem
portion
Leaves have higher quality, 2x more CP in leaves
in than stems, less structural CHO (fiber) in leaves
than stems
Ratio is dynamic, changes over time; stem leaf
Harvest, store, and feed LEAVES
What is the cost of poor quality
forage?
Table 5. The effect of forage quality on predicted
forage day matter intake of ruminants.
% Forage
NDF (dry basis)
38
40
42
44
46
48
50
52
54
Dry Matter Intake
as % of Body Weight
3.16
3.00
2.86
2.73
2.61
2.5
2.4
2.31
2.22
AAdapted
d a p t efrom
d data
f rom
data by1985;
Mertens,
by Mertens,
Pioneer1985
Forage Manual
F r o m: Pioneer Forage Manual
NDF is a measure of quality. As percent fiber increases,
intake decreases, leading to a decrease in animal production.
http://www.uwex.edu/ces/forage/pubs/auction.htm
As the forage quality increases, the price paid
increases. High quality forage has a higher
value.
Milk production (lb/acre)
Milk production
15000
Increase = $400 profit
12000
9000
6000
3000
0
low-quality hay
high-quality hay
Milk production increases, profits increase with
higher quality hay.
Table 7. Effect of alfalfa quality on rate of gain and feed efficiency of 400-600
pound steer calves. All values on a dry matter basis.
Hay quality:
Bloom:
CP
ADF
DDM
Intake (% of
body weight)
Daily gain
(lb per day)
Pounds of
feed
(/lb of gain)
Superior
Pre-bud
23
21
73
Premium
Bud
20
26
69
Fair
Early
17
34
62
Poor
Full
14
43
55
3.5
3.0
2.5
2.0
2.2
1.9
1.2
.08
7.0
9.0
12.0
15.0
Source: University of Nevada-Reno.
From: Pioneer Forage Manual
• Forage quality decreases with plant maturation.
• Daily gain (lb of gain per day) decreases with decreasing
forage quality.
• Concentrate:forage ratio increases with forage
age, resulting in increase costs.
Can I determine forage quality by just
looking at it?
In the field before harvest?
In storage?
Can I determine forage quality by just
looking at it?
In the field before harvest?
• Stage of maturity
• Leafiness vs. steminess
In storage?
• Stage of maturity at harvest
• Leafiness vs. steminess
• Green color
• Odors, molds, dust
• Foreign material, weeds
What does the consumer (animal) want?
• Maximum quantity, dry matter/feeding
• Maximum quality, nutritive value
The goal of the producer:
• Maximum quantity (yield), dry matter/A
• Maximum quality, nutritive value
• Stand persistence, perennial stand remains
healthy over years
Persistence, defined as the ability of
perennial plants to remain alive and
productive over a long periods of time.
• Hardiness and winter survival
• Disease
• Management
Winter hardiness (cold resistance, winter
dormancy)
Metabolic changes:
 Begins with cooler temperatures and short
daylengths
 Growth slows, no new plant material
 Photosynthesis still takes place, sugar is not used
for growth but placed in the CHO reserves, roots for
legumes, stem bases for grasses
 Increase in sugar storage in crown region, stem
bases, or root, decreases the freezing point of the
cell sap, used for regrowth in the spring
• Decrease in free water, decreases the potential for
ice formation within the cell and between cells
•
•
Species dependent
• Grasses > winter hardiness compared to
legumes
• Perennial ryegrass, tall fescue < winter
hardiness
Varietal differences
• Breeding programs
• Annual alfalfa
• Stand persistence
•
•
Plant differences
• Actively growing plants > susceptibility to winter
damage; new growth is damaged if the
temperature drops below 24-25 F.
• Why? Water content is greater and sugar used for
growth as opposed to storage
Plant parts differ in their susceptibility to winter
damage
• Leaves > than roots > than crown region
• Related to the level of water in the plant parts
Management for persistence:
Enhance soil cover
• No harvest after frost
• Grasses catch more snow than legumes,
mixture
• Reduce free water in the plant
• Do not irrigate in the fall
• Reduce the potential of actively growing plants
• Do not harvest 4-5 wks before 1st killing frost
• Fertility
• Do not apply N prior to killing frost
• P and K enhance winter survival
•
When is the ideal time to harvest:
• Quantity
• Persistence
• Quality
Ideal time to harvest:
• Quantity, at seed formation
• Persistence, at maximum levels of
stored CHO
• Quality, a young, vegetative stage
Ideal time to harvest:
• Compromise between quantity, stand
persistence, and quality.
Compromise between quantity, stand persistence, and quality
Products
• Silage/haylage - wet; 60 - 40% moisture
• Hay - dry; <20% moisture
• Pellets - dehydrated; quickly dried at 300-
1000C; ground; pelleted or cubed
Field/harvest losses
•
Physical
• DM loss; leaf loss or leaf shattering; handling
forage particularly when less moist
Less drying time, wetter product (haylage),
less leaf loss
Table 21 from Silage and Hay Preservation.
NRAES, Bulletin 5. Handout
Physiological
• Respiration; sugars become heat and CO2; slows
and becomes inhibited at moisture content < 20%
•
•
Faster drying rate, less respiration loss
•
Leaching nutrients because of rain
Faster drying rate, less time in the field, less
chance of getting rained on
Comparison of forage quality of standing alfalfa
forage just prior to harvest with the quality of hay
produced without rain damage or hay exposed to
rain damage. Yield is in tons DM/acre. (Collins 1990)
120
100
80
2.0
1.7
1.5
60
40
20
0
Yield (%)
Crude protein
(%)
Alfalfa before cutting
Digestibility (%)
Well-cured hay
NDF (%)
Rain-damaged hay
Drying
• grasses dry faster than legumes
• mature crop dries faster
• heavier yields dry slower
• waxy surface on leaves and stems
• leaves dry at a faster rate than stems
• stem thickness, 1st cut thicker than 2nd
cut
Cutting:
Cutting: at appropriate stage of maturity, at a
height of 2-4 inches
Mechanical conditioning: involves crushing or
crimping the stems, in order to increase their
drying time, especially legumes
Chemical conditioning: Potassium or sodium
carbonate, sprayed on at the time of mowing
Swath manipulation, tedding, tines rotate to stir,
spread, and fluff the swath; can spread out the
swath after conditioning, decreasing drying time
Raking, moves the wetter hay from the bottom to the
top
Baling:
• Conventional rectangular bales, 50-135 lb,
most commonly used package for cash hay,
safe baling moisture% is 20%
• Big round bales, 500-2000 lb, less labor, feed
on the farm, safe baling moisture% is 18%
• Large rectangular, 900-2000 lb, safe baling
moisture% is 12-16%
Hay preservatives: propionic acid, allow hay to
be baled at higher moisture contents, reduces
the curing time by one day
Storage loss
•
Mold growth, at 20-35% moisture
•
•
•
•
Molds consume nutrients, release CO2,
water, and heat
Heat may lead to fires
Molds produce toxins, spores that cause
lung damage
Reduces the value of the hay for sale
•
Browning reactions, caramelization,
nonenzymic browning, Maillard reaction
• Results from release of heat, due to
respiration
• Proteins and amino acids combine with
sugars to form a brown polymer,
resembling lignin, reduced digestibility
• Releases heat causing more browning,
hay fires
Weathering
• Weathering: leaching of nutrients,
outside layer has greatest weathering
• % hay loss decreases with increased
bale size
Silage/Haylage
Silage/haylage - wet; mowed, wilted,
chopped, stored, fermented
Advantages of silage/haylage
• Less time in the field, curing
• Preserves more nutrients than hay
• Reduces weather risks
• Reduces field losses
• Less respiration
• Less rain damage
• Less mechanical manipulation, less
shattering
• Mechanized harvesting and feeding systems
Disadvantage of silage/haylage
•
•
•
•
High equipment costs
Contains less vitamin D than hay
Potential for more storage loss
Loss of nutrients through the effluent
Making silage/haylage
•
I. Aerobic phase, respiration
C6H12O6 + 6O2
6CO2 + 6H2O + heat
Length of phase is dependent of the O2
concentration
Reduction in sugar (nutrients), decrease in net
energy, increase in % fiber
Increase in temperature, ideal is 70-90 F, if too
high then fire and Maillard process
Goal is to decrease O2 concentration as quickly as
possible
Making silage/haylage
•
I. Aerobic phase, respiration
Goal is to decrease O2 concentration as quickly as
possible
• Compaction of the forage
• Proper cut length, 1/2-1 inch for direct cut
silage; 1/4 to 1/2 inch for wilted; 3/8 inch for
forage; 1/4 inch for corn
• Sealing the silo, keeping O2 out
• II. Lag phase
III. Fermentation phase, anaerobic
The bacteria converts carbohydrates to a small
amount of acetic acid first, then lactic acid
•
glucose (6C)
2 lactic acid (2, 3C) + heat
4% loss of energy in the form of heat
High lactic acid levels causes the pH to drop,
ideal would be 70% of the acid present was
lactic acid. Lactobacillus bacteria
14 days for good fermentation
•
IV. Storage for a long time
When fermentation process goes bad . . .
• Clostridia, predominate bacteria, spores in
•
•
•
•
manure and the soil
Clostridia converts lactic acid to butyric acid
(4C) and 2CO2
Substantial energy loss, 23% (butyric) vs 4%
(lactic)
Rancid odor, reduced palatability, high level of
ammonia-N, greater than 10% of total N, pH
higher than 5.0
Too little carbohydrates (low sugar content),
moisture content too high, high pH (above 5.0),
aerobic condition, low numbers of Lactobacillus
Silage additives
•
•
•
•
•
Acids to decrease pH, commonly used in Europe: Formic
acid; propionic acid, usually not cost effective
Microbial inoculates, increase the number of
Lactobacillus bacteria, results are variable, successful if
increasing the bacteria numbers by at least 10%
Carbohydrates, grain, molasses
• Increase fermentable CHO
Nonprotein N
• Increases CP
Enzymes, hemicellulase, cellulase
• Breakdown of structural CHO, more fermentable CHO
• Varying degrees of success
Added labor and costs, better to harvest at
appropriate stage
Purchased products are not
substitutes for good management
Garbage in
garbage out
Oxygen
Feeding
Phase
Unloading
• Keep silage covered
• Remove only what is needed
• Little surface face area
• Smooth surface area
Forages Vol. I, An Introduction to Grassland Agriculture, 6th ed.
When K increases, winter survival increases.
When N increases, winter survival decreases.
Forages Vol. I, An Introduction to Grassland Agriculture, 6th ed.
Comparison of forage quality of standing alfalfa
forage just prior to harvest with the quality of hay
produced without rain damage or hay exposed to
rain damage. Yield is in tons DM/acre. (Collins 1990)
120
100
80
2.0
1.7
1.5
60
40
20
0
Yield (%)
Crude protein
(%)
Alfalfa before cutting
Digestibility (%)
Well-cured hay
NDF (%)
Rain-damaged hay