Transcript Pasture Management to Reduce Weed Competition

Keys to Maximizing
Your RFQ Score
Dr. Dennis Hancock
Extension Forage Specialist
Crop and Soil Sciences – UGA
What is the difference?
1) Digestible energy
2) How much can be eaten
What is “high quality forage?”
• Forage that is highly digestible (i.e., high TDN)
• Large amounts of the forage can be consumed
(i.e., high DMI).
• Relative Forage Quality (RFQ) =
TDN * DMI/1.23
Relative Forage Quality (RFQ)
75
100
125
150
175
Quality Required
• Dairy, 1st 120 days
• Dairy calf
• Dairy, last 200 days
• Heifer, 3-12 mo.
• Stocker cattle
• Weanling horse
• Mature horse, int. work
• Heifer, 12-18 mo.
• Lactating beef cow
• Lactating mare
• Mature horse, mod. work
• Heifer, 18-24 mo.
• Dry cow
• Mature horse, lt. work
200
225
What Affects Forage Quality?
Primary Factors Affecting Forage Quality
Factor
Recommendation
Plant Maturity
Cut bermudagrass every 4-5 wks; cut tall fescue in
the boot or early head stage.
Forage Species
Use the highest-quality species that will persist in
your environment.
Bale Storage
Protect bales from rainfall and weathering during
storage (i.e., barn, tarp, etc.)
Rain During Curing
Avoid cutting if significant rainfall (> 0.50 inches) is
predicted during curing.
Moisture at Baling
Allow forage to dry to the appropriate moisture
(Round: 15%; Square: 18%)
Fertilization
Provide fertilizer based on soil test recommendations
Variety
Use varieties that have proven to be higher in
quality.
The Paradox of Forage
Quality and Quantity
12000
Growth Curve
Digestibility & Palatability
Forage Mass
(dry lbs/acre)
10000
8000
6000
4000
2000
0
0
5
10
15
20
25
30
Days of Growth
35
40
45
50
Fescue Maturity- Digestibility
Digested DM/Ac
Undigested DM/Ac
Tons/Acre
2.5
2.0
1.5
JUST MORE MANURE!!!
1.0
0.5
0.0
Late boot
Majority of hay harvested at hard seed stage
Only truly applicable with spring harvest
Early flower
Seed dough
Bermudagrass Harvest Interval:
Effects on Protein and Digestibility
Percent, %
60
55.0
49.0
45
50
40
30
20
10
15.8
6.3
5.3
0
Crude Protein
4 weeks
McCollough and Burton., 1962
DMI 11.9, 8.8, 9.5 lbs
ADG 1.2, .9, 0 lbs
8 weeks
Digestibility
13 weeks
Harvest Timing
Recommendations
•Hybrid Bermudagrass
-
1st cut at 12-16 inches
Subsequent cuttings at 3.5-5 week intervals
• Tall fescue, ryegrass, orchardgrass, etc.
-
Spring cut at early flower stage
Mid to late boot stage for higher quality
Subsequent cuttings at 10-12 inches (better quality)
• Alfalfa
-
Spring cut at when 10-20% of plants are blooming
Cut at late bud – 10% bloom stage
Primary Factors Affecting Forage Quality
Factor
Recommendation
Plant Maturity
Cut bermudagrass every 4-5 wks; cut tall fescue in
the boot or early head stage.
Forage Species
Use the highest-quality species that will persist in
your environment.
Bale Storage
Protect bales from rainfall and weathering during
storage (i.e., barn, tarp, etc.)
Rain During Curing
Avoid cutting if significant rainfall (> 0.50 inches) is
predicted during curing.
Moisture at Baling
Allow forage to dry to the appropriate moisture
(Round: 15%; Square: 18%)
Fertilization
Provide fertilizer based on soil test recommendations
Variety
Use varieties that have proven to be higher in
quality.
Quality Differences in the
Major Forage Species
Digestible DM, %
High
Production
Legumes
Tropical Annual
Grasses
50
Tropical Perennial
Grasses
60
Cool Season Perennial
Grasses
70
Cool Season Annual Grasses
80
40
Figure 2. Digestibility ranges of major forage types. Note that the ranges
overlap, but some forage types are more likely to be lower in quality than
Mod.
Production
Maint.
Quality Provided
Typical Range in Quality of
Common Forages
Alfalfa
Other Legumes
Cool Season Annual Grasses
Cool Season Peren. Grasses
Bermudagrass
Summer Annual Grass
75
100
125
150
175
200
Relative Forage Quality (RFQ)
225
Primary Factors Affecting Forage Quality
Factor
Recommendation
Plant Maturity
Cut bermudagrass every 4-5 wks; cut tall fescue in
the boot or early head stage.
Forage Species
Use the highest-quality species that will persist in
your environment.
Bale Storage
Protect bales from rainfall and weathering during
storage (i.e., barn, tarp, etc.)
Rain During Curing
Avoid cutting if significant rainfall (> 0.50 inches) is
predicted during curing.
Moisture at Baling
Allow forage to dry to the appropriate moisture
(Round: 15%; Square: 18%)
Fertilization
Provide fertilizer based on soil test recommendations
Variety
Use varieties that have proven to be higher in
quality.
14 inches
~74% of the bales volume is contained in that 14 inches.
Moisture distribution of mixed
grass-legume round bales stored on
the ground
% Moisture
Twine Wrapped
Shinners, University of Wisconsin
Net Wrapped
Moisture distribution of mixed
grass-legume round bales stored on
the ground vs. elevated
% Moisture
Twine Wrapped
Shinners, University of Wisconsin
On a Pallet
Primary Factors Affecting Forage Quality
Factor
Recommendation
Plant Maturity
Cut bermudagrass every 4-5 wks; cut tall fescue in
the boot or early head stage.
Forage Species
Use the highest-quality species that will persist in
your environment.
Bale Storage
Protect bales from rainfall and weathering during
storage (i.e., barn, tarp, etc.)
Rain During Curing
Avoid cutting if significant rainfall (> 0.50 inches) is
predicted during curing.
Moisture at Baling
Allow forage to dry to the appropriate moisture
(Round: 15%; Square: 18%)
Fertilization
Provide fertilizer based on soil test recommendations
Variety
Use varieties that have proven to be higher in
quality.
DM Loss, %
The Effect of Rainfall on
DM Loss
Scarbrough et al., 2005
Rainfall, in.
DM Loss, %
Crop Moisture Lessens Rain
Damage on Bermudagrass
76% Moisture, Not Significant.
Scarbrough et al., 2005
Rainfall, in.
NDF, %
Crop Moisture Lessens Rain
Damage on Bermudagrass
Scarbrough et al., 2005
Rainfall, in.
The Effect of Rain on
Tall Fescue Hay
No Rain
2.10
Rain Damage
1.92
NDF, %
68.1
76.0
Digestibility, %
63.2
59.7
Intake, % of b.w.
Turner et al., 2003
Primary Factors Affecting Forage Quality
Factor
Recommendation
Plant Maturity
Cut bermudagrass every 4-5 wks; cut tall fescue in
the boot or early head stage.
Forage Species
Use the highest-quality species that will persist in
your environment.
Bale Storage
Protect bales from rainfall and weathering during
storage (i.e., barn, tarp, etc.)
Rain During Curing
Avoid cutting if significant rainfall (> 0.50 inches) is
predicted during curing.
Moisture at Baling
Allow forage to dry to the appropriate moisture
(Round: 15%; Square: 18%)
Fertilization
Provide fertilizer based on soil test recommendations
Variety
Use varieties that have proven to be higher in
quality.
Heat Damage to Crude Protein
Heat-Damaged
Protein
Protein
Useable
Protein
DM Intake
Heat
Primary Factors Affecting Forage Quality
Factor
Recommendation
Plant Maturity
Cut bermudagrass every 4-5 wks; cut tall fescue in
the boot or early head stage.
Forage Species
Use the highest-quality species that will persist in
your environment.
Bale Storage
Protect bales from rainfall and weathering during
storage (i.e., barn, tarp, etc.)
Rain During Curing
Avoid cutting if significant rainfall (> 0.50 inches) is
predicted during curing.
Moisture at Baling
Allow forage to dry to the appropriate moisture
(Round: 15%; Square: 18%)
Variety
Use varieties that have proven to be higher in
quality.
Variety
Use varieties that have proven to be higher in
quality.
Yield and Digestibility of
Bermudagrass Hybrids
Primary Factors Affecting Forage Quality
Factor
Recommendation
Plant Maturity
Cut bermudagrass every 4-5 wks; cut tall fescue in
the boot or early head stage.
Forage Species
Use the highest-quality species that will persist in
your environment.
Bale Storage
Protect bales from rainfall and weathering during
storage (i.e., barn, tarp, etc.)
Rain During Curing
Avoid cutting if significant rainfall (> 0.50 inches) is
predicted during curing.
Moisture at Baling
Allow forage to dry to the appropriate moisture
(Round: 15%; Square: 18%)
Variety
Use varieties that have proven to be higher in
quality.
Fertilization
Provide fertilizer based on soil test recommendations
CP in Bermudagrass Forage
as Effected by N Fertilization
18
16
T 85 F
T 85 C
% Protein
14
12
10
8
6
4
2
0
200
300
400
lbs N
Source: Dr. Bill Anderson, USDA-ARS Tifton
500
600
700
Effect of N Rates on
Bermudagrass CP & Digestibility
20
15
10
5
0
Crude Protein
0
Burton et al.
Digestibility
400
Annual lbs N/year
1400
70
68
66
64
62
60
58
56
54
52
50
Digestibility, %
Crude Protein, %
25
Does fertility or harvest timing affect
quality more?- Crude Protein
(4X as much N)
Bromegrass
Colovos et al. 1961
Does fertility or harvest timing
affect quality more?- Digestibility
(3.8 X as much N)
Bromegrass
Colovos et al. 1961
Primary Factors Affecting Forage Quality
Factor
Recommendation
Plant Maturity
Cut bermudagrass every 4-5 wks; cut tall fescue in
the boot or early head stage.
Forage Species
Use the highest-quality species that will persist in
your environment.
Bale Storage
Protect bales from rainfall and weathering during
storage (i.e., barn, tarp, etc.)
Rain During Curing
Avoid cutting if significant rainfall (> 0.50 inches) is
predicted during curing.
Moisture at Baling
Allow forage to dry to the appropriate moisture
(Round: 15%; Square: 18%)
Variety
Use varieties that have proven to be higher in
quality.
Fertilization
Provide fertilizer based on soil test recommendations
Be Careful of Cutting Height
Write this down in
BIG BOLD letters!
“GRASS GROWS GRASS.”
Parting Thoughts
• RFQ is chiefly defined by digestibility
and DM intake
• Plant maturity trumps ALL other factors
- Even more important than forage
species
• Rain damage is a problem, but letting a
plant get overly mature to avoid a ½
inch rain is even more problematic
• Avoid cutting the forage too short
- It reduces quality and slows the
rate of regrowth
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