principles of managed grazing karen hoffman resource conservationist – animal science usda-nrcs...
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Principles of Managed Grazing
Karen HoffmanResource Conservationist – Animal Science
USDA-NRCSNorwich, NY, USA
Natural Resources Conservation Service
Managed Pasture Systems
• Small paddocks
• Short duration
• Rest interval
• 6-8” forage height
The goal of a pasture plan is to ensure the forage supply is kept in balance with the forage demand
Rotational Stocking Method
HIGH FORAGE SUPPLY(SPRING AND EARLY SUMMER)
GRAZE HALF – HARVEST HALF
CUTFIRST
FORHAY
ORSILAGE
CUTFIRST
FORHAY
ORSILAGE
LOW FORAGE SUPPLY(MID-SUMMER AND FALL)
GRAZE ALL
15 day rest period in the Spring30 day rest period in the Summer
A High Value Pasture is:“A unit or area of land on which exists a suitable amount, type and distribution of vegetation that when utilized with a sufficient level of management complements or meets the nutritional requirements of the resident livestock for as long a time period is as possible.”
In other words, there is enough good quality, palatable forage available for animals to perform well!
Low Value PastureHigh In Forage Quality – Low In Forage Quantity
0
2
4
6
8
10
12
14FO
RA
GE H
EIG
HT (
INC
HES)
Low Value PastureHigh In Quantity – Low In Quality
FORA
GE
HEI
GH
T (IN
CHES
)
0
2
4
6
8
10
12
14
High Value PastureHigh Forage Yield – High Forage
QualityFO
RA
GE H
EIG
HT (
INC
HES
)
0
2
4
6
8
10
12
14
Pasture plants are alive and actively growing.
They change in yield and quality every day and even over the course of a few hours.
Time
3 PHASES OF PASTURE GROWTH3 PHASES OF PASTURE GROWTH
0
2
4
6
8
10
12
14
16
18
20PHASE IIISTEMMY
OVER-MATURE
PHASE ILEAFY
IMMATURE
PHASE IILEAFY
MATURE
0 5 10 15 20 25
NUMBER OF DAYS GROWTH0 10 20 30 40 50SUMMER
SPRING
LOW
Q
U
A
N
T
I
T
Y
Q
U
A
N
T
I
T
Y
HIGH LOW
HIGH
Q
U
A
L
I
T
Y
Q
U
A
L
I
T
Y
YOUNG VEGETATIVE PLANT
LEAF PLANT CELL
CELL CONTENTS ± 80%
CELL WALL± 20%
OLD OVER-MATURE PLANT
LEAF PLANT CELL
CELL CONTENTS ±20%
CELL WALL± 80%
RELATIVE PROPORTION OF FIBER COMPONENTS
PROTEIN SUGARS40% CELLULOSE
50% HEMICELLULOSE
10% LIGNIN
OLD OVER-MATURE PLANT
YOUNG VEGETATIVE PLANT
PROTEIN SUGARS20% CELLULOSE
30% HEMICELLULOSE
50% LIGNIN
Typical Forage Quality
NUTRIENT PASTURE HAY HAYLAGE
Dry Matter % 20-25 88-92 35-40
Crude Protein % 20-30 8-14 14-20
Net EnergyG, Mcal/lb .50-.60 .40-.50 .45-.55
ADF%* 20-30 30-40 30-40
NDF%** 40-50 55-65 45-55
* Acid Detergent Fiber – cellulose + lignin
**Neutral Detergent Fiber – hemicellulose + cellulose + lignin
Protein• Protein from pasture > animal req’ts• 20 – 30% crude protein from pasture• Dairy cow needs 16-17%• Beef, sheep, etc. need 12-14% depending on production phase
• Protein from pasture > rumen bacteria req’ts• 70 – 80% degradability
• Feeding energy supplements can help to dilute protein
How Excess Degradable Protein Wastes Energy
Degradable Protein
Used by microbes Not used protein + carbohydrates converted to ammonia microbial protein - energy used by cows ammonia into blood
ammonia in blood to
liver energy
urea excretion liver converts to urea
Supplementation
• Dilute the pasture protein• Feed a little dry hay
• Lower protein than pasture• Substitutes for pasture intake
• Use the pasture protein• Feed a little ground corn
• Provides non-fiber carbs (NFC)• Rumen bugs use to make more bugs
Non-Fiber Carbohydrates (NFC)
• Dairy• Critical for high milk production• Caution – no grain not easy
• Beef• Only if gains are low
• Sheep, goats• Breeding, lactating w/multiples, weaned lambs or kids
• Camelids• No clear guidelines – be careful not to overfeed
Non-Fiber Carbohydrates (NFC)
• Horses• Amount depends on level of work
• Swine• Grain higher proportion of diet
• Poultry• 70-90% of diet with insects, grass, etc balance
None of these species types needs NFC’s for rumen or excess pasture protein issues
Supplementation
• Salt• Supply free-choice
• Loose vs. blocks• Self-limiting
• Mix in with grain• Limits intake
• Minerals• Can be in trace mineral salt block• May need extra selenium• Be careful of copper & molybdenum content
• Sheep and goat label• Camelids have similar toxicity problem
Kelp• Approved for organics• Source of minerals, vitamins, anti-oxidants• High iodine content
• Not problematic
• Limited research• Boosts immune system• Reduces pinkeye
Parasite Issues• Sheep and goats – major issue• Barber pole worm, brown stomach worm, coccidia, P. tenuis, flukes, tapeworms, lungworms, etc.• Dewormer resistance
• use FAMACHA and strategic deworming• Pasture management
• longer rest periods to break lifecycle – 45-60 days• graze taller forage, leave more residual
Parasite Issues• Cattle – minor issue• Roundworm, flukes, tapeworms• Same lifecycle as sheep parasites, but species specific• Dewormers typically used twice in spring – resistance issue• Young animals most susceptible – cattle become more resistant with age• Pasture management
• Young animals on “clean” pasture• Don’t overgraze
Multi-species Grazing –cattle + sheep
• Advantages• More uniform grazing of pasture• Predator protection• Parasite protection
• Disadvantages• Mineral supplementation for cattle vs. sheep/goats
• Systems• Leader-follower• Co-grazing• “Strategic rotation” for parasite control
“Strategic Rotational” Stocking Method
Sheep
CUTFIRST
FORHAY
ORSILAGE
Cattle
45-60 day rest period for sheep20-30 day rest period for cattle
Multi-species Grazing -poultry + ruminants
• Advantages• Poultry break up manure, spread nutrients• Poultry eat fly larvae, snails (?)• Reduced grain consumption
• Disadvantages• Labor-intensive if using pens• Messy if true “free-range”• Predator problems
Health Considerations• Pasture provides health benefits
• Boosts immune system – reduces stress
• Vitamins A & D, natural minerals & antioxidants, medicinal plants
• Sunshine, fresh air, naturally comfortable environment, clean, soft footing, exercise
• Need to manage grazing well before health improves
Summary• Managed pasture is beneficial for both health and nutrition of all
species
• If pasture main source of feed, must be managed for quality and quantity
• Parasite management needed with small ruminants
• Benefits to grazing different species together
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