MIG Rules You Need to
Know
Dr. Dan Morrical
Iowa State University
Grass Growth is Not Uniform

Manage supply
– Increasing paddock # in summer
» Warm season grasses
» Hay field re-growth
– Change stocking rate
» Not very practical
» Example short duration stockers
% Rest
The relationship between
paddock number and plant rest
100
90
80
70
60
50
40
30
20
10
0
1
2
3
4
5
6
8
10 12 16 20
Number of Paddocks
Why rest is needed
Grazing animals are selective in what
they eat
 Preferred species are over comsumed

– Weakens vigor and reduces composition
– Allows invaders
– Root system dies back with grazing
How Often Should I Rotate?

Factors to assess
– Animal needs
» Stockers vs. dry cows
– Time
» Cell location, human resource

Stage of growing season
– Fast growth - fast rotation
– Slow growth - slow rotation
Utilization
Varies from 0-100%
 More paddocks = higher utilization rate
 Balance is derived

– Over use - slow re-growth and long rest
– Under use - forage accumulation
- decreased quality
Utilization Rates by Grazing
Intensity
Length of
Grazing (days)
.5
1
2
3
4-7
10-14
Continuous
% Utilization
of DM Available
75
70
65
60
40-50
35
30
Utilization Rate

Defined by the % forage consumed vs.
forage available at turn in
Example 2000 lbs at turn in
 1000 lbs remaining at removal
 1000/2000 = 50% Utilization rate

Paddock Layout

No perfect system
Rule - square better
1.
2.
3.
4.
Improved uniformity
Less fence
Less distance traveled
Makes for easier clipping or baling
Examples
Improper
gate
location
Central
Watering
Hub
Center over utilized, light shaded
area is correctly utilized and
perimeter area is under utilized.
Central
watering
hub
Gate placement and watering
design.
Examples
Water
Darkest shaded area is over
utilized, light shaded area is
correctly utilized and the
white area is under utilized.
Water
Alternative to wagon wheel
design with poor water
location.
The grazing pattern and distance to
cover paddocks of different shapes.
R
R
Gate
Gate
Fencing sloped areas
Incorrect method of
fencing slopes
Water lane
Ridge
Slope
Bottom
Correct methods of fencing slopes
Getting Started with Paddock Layout
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
Pencil and paper and aerial or
soil map
Flag proposed system
Check gate location and animal
flow
Seek input
Modify
Build fence
Successful Systems =
Excess Early Forage

Layout paddocks with areas that are
hayable separatel

If three or four hayable paddocks lay
together, subdivide with temporary
fence post harvest
Sacrifice Paddock (s)

Why
– Abuse small area vs whole pasture
– Weather is not always perfect
– Easy to get to
– Easy to renovate
– Many recover with more rest
MIG Success
Flexible
 Productivity increases over years
 Labor is only an issue with location
 Change mind set
 Pasture is the cheapest feed source
