1. Improving Intake of Medusahead: Is it Possible?
Tyler Hamilton, Juan Villalba and Beth Burritt

2. What ‘s Wrong with Medusahead?
1.
2.
3.
4.
5.
It produces little biomass
It’s mostly stem with little leaf
It has nasty awns
It’s high in silica and low in nutrients
It produces a thatch that smothers other
plants, doesn’t readily breakdown, and is
highly flammable.

3. “A team of genetic engineers couldn’t have devised
a more ecologically lethal and effective invasive
weed than the aptly named medusahead rye.”

4. "It's like a piece of land that's stolen from you or from
your ranch that no longer produces feed.”

5. Questions
1. How does supplementation intake of
and preference for medusahead?
2. Is medusahead aversive?
3. How does the addition of silica
dioxide to the diet affect intake?

6. How much medusahead will a sheep eat?
Do supplements enhance intake and preference?
Group 1:
High-Energy
Group 2:
High-Protein
Group 3:
Choice
Group 4:
No Supplement
After 20 min., all animals had ad libitum access to fresh medusahead for 5 hours/day.
Trial 1
Trial 2
Measured intake and preference
Trial 3

7. Supplement Ingredients and Nutritional Composition
Ingredient, %
Alfalfa
Soybean Meal
Beet Pulp
Barley
High Energy
High Protein
60
40
70
30
DE, Mcal/kg
NDF, %
Protein, %
3.54
31.7
11.3
3.00
31.9
28.8
Protein/Energy
3.2
9.6

8. Intake of Medusahead (Seedhead Emergence)
by Lambs Fed Three Different Supplements or
No Supplement
Intake, g/Kg0.75
8
6
4
2
SEM
0
1
2
3
No Supplement
4
5
High Energy
6
7
High Protein
8
9
Choice
10

9. Translation:
Medusahead: 4 to 8 g/kg 0.75/5 hr
Requirement: 55 g/kg 0.75/d

10. Intake of Medusahead Intake (Seedhead
Emergence) by Lambs Fed a High Energy
Supplement or No Supplement
a
Intake ( g/kg 0.75)
8
a
a
6
4
b
b
b
2
No Supplement
High energy
0
1
2
3
4
5
6
7
8
9
10

11. 8
Intake of Medusahead (Mature) by Lambs Fed
Three Different Supplements or No Supplement
Intake, g/Kg0.75
No Supplement
High Energy
6
High Protein
Choice
4
2
0
1
2
3
4
5
6
7
8
9
Figure 2

12. Intake, g/Kg0.75
20
Intake of Medusahead (Thatch) by Lambs Fed
Three Different Supplements or No Supplement
No supplement
15
High energy
High Protein
Chioce
10
5
SEM
0
1
2
3
4
5
6
7
8
9
10
Figure 2

13. Comparison of Medusahead
Seedhead Emergence vs. Thatch
20
Intake (g/kg 0.75)
15
Control
HiE
Hi Pro
Choice
Trial 1 – Seedhead Emergence
10
5
0
20
15
Trial 3 – Thatch
10
5
0
1
2
3
4
5
6
7
8
9
10
Figure 2

14. Trial 1 – Total Intake – Seedhead Emergence
Intake of Tall Fescue
Hay, Medusahead and
Supplements at Three
Stages of Medusahead
Maturity
Hay
60
Medusahead
40
Supplement
20
0
None
Trial 2 – Total Intake – Mature
HE
HP
CH
Trial 3 – Total Intake – Thatch
60
60
40
40
20
20
0
0
None
HE
HP
CH
None
HE
HP
CH
Figure 1

15. Trial 1 - Seedhead Emergence and Hay
60
Choice between TF hay
and medusahead at
three stages of maturity
40
20
0
C
HE
HP
Merdusahead
Trial 2- Mature and Hay
CH
Hay
Trial 3 – Thatch and Hay
60
60
40
40
20
20
0
0
C
HE
HP
CH
C
HE
HP
CH

16. Crude Protein and Silica Content of Medusahead
at Three Stages of Maturity
12
10
%
8
Green
6
Mature
Thatch
4
2
0
Crude Protein
Silica

17. Is Silica Involved in the Intake Response to
Medusahead?
Familiarized with alfalfa from 8 am to noon. Then, fed tall fescue
hay from noon to 2pm.
After familiarization, lambs were fed their respective treatment
diets (8 am to noon) and tall fescue hay from noon to 2pm.
Alfalfa - Control
Alfalfa + 2.5% SiO2
Alfalfa + 4.5% SiO2

18. 120
120
Before adding Silica to Alfalfa
Alfalfa
110
110
2.5% Si
Intake (g/kg 0.75)
100
Silica added to Alfalfa
100
4.5% Si
90
90
80
80
70
70
30
Tall Fescue Intake Before
Adding Silica to Alfalfa
30
25
Tall Fescue Intake After
Adding Silica to Alfalfa
25
20
20
15
15
10
10
5
5
0
0
1
2
3
4
5
1
2
3
4
5

19. Is Medusahead Aversive?
Fed coconut-flavored beet pulp
Then they received intraruminal infusions of:
1-LiCl (1.5 mg/Kg BW – Aversive)
2-Tall Fescue Hay (4g/Kg BW – Not
Aversive)
3-Medusahead (4g/Kg BW – Unknown)
(Average amount eaten in Trial 1)

20. Is Medusahead Aversive?
Intake, g/Kg0.75
25
20
15
10
Hay
5
LiCl
Medusahead
0
1-Jul
2-Jul
3-Jul

21. Results
• Intake of and preference for medusahead is
enhanced (sort of) by supplements high in
energy.
• Intake of medusahead is low and decreases even
further as the plant matures.
• Intake of medusahead by unsupplemented
animals was low, even though they ate least DM
and nutrients.
• Medusahead does not to induce a food aversion
in sheep.
• Silica likely reduces intake of medusahead.

22. Questions?