Improving Intake of Medusahead: Is it Possible?

Tyler Hamilton, Juan Villalba and Beth Burritt

What ‘s Wrong with Medusahead?

1. It produces little biomass2. It’s mostly stem with little leaf3. It has nasty awns 4. It’s high in silica and low in nutrients5. It produces a thatch that smothers other

plants, doesn’t readily breakdown, and is highly flammable.

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

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

Questions1. 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?

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.

Measured intake and preferenceTrial 1 Trial 2 Trial 3

Ingredient, % High Energy High Protein

AlfalfaSoybean MealBeet PulpBarley

DE, Mcal/kgNDF, %Protein, %

Protein/Energy

7030

3.5431.711.3

3.2

6040

3.0031.928.8

9.6

Supplement Ingredients and Nutritional Composition

1 2 3 4 5 6 7 8 9 100

2

4

6

8

No Supplement High Energy High Protein Choice

Inta

ke, g

/Kg0

.75

SEM

Intake of Medusahead (Seedhead Emergence) by Lambs Fed Three Different Supplements or

No Supplement

Medusahead: 4 to 8 g/kg 0.75/5 hr

Requirement: 55 g/kg 0.75/d

Translation:

1 2 3 4 5 6 7 8 9 100

2

4

6

8

No SupplementHigh energyIn

take

( g/

kg 0

.75)

Intake of Medusahead Intake (Seedhead Emergence) by Lambs Fed a High Energy

Supplement or No Supplement

bbb

a aa

Figure 2

1 2 3 4 5 6 7 8 90

2

4

6

8

No Sup-plementHigh EnergyHigh ProteinChoice

Inta

ke, g

/Kg0

.75

Intake of Medusahead (Mature) by Lambs Fed Three Different Supplements or No Supplement

Figure 2

1 2 3 4 5 6 7 8 9 100

5

10

15

20

No sup-plementHigh energyHigh ProteinChioce

Inta

ke, g

/Kg0

.75

SEM

Intake of Medusahead (Thatch) by Lambs Fed Three Different Supplements or No Supplement

1 2 3 4 5 6 7 8 9 100

5

10

15

200

5

10

15

20

ControlHiEHi ProChoice

Figure 2

Trial 3 – Thatch

Trial 1 – Seedhead Emergence

Inta

ke (g

/kg

0.75

)Comparison of Medusahead

Seedhead Emergence vs. Thatch

None HE HP CH0

20

40

60 HayMedusaheadSupplement

Figure 1

None HE HP CH0

20

40

60Trial 2 – Total Intake – Mature

Trial 1 – Total Intake – Seedhead Emergence

None HE HP CH0

20

40

60Trial 3 – Total Intake – Thatch

Intake of Tall Fescue Hay, Medusahead and Supplements at Three Stages of Medusahead Maturity

C HE HP CH0

20

40

60

C HE HP CH0

20

40

60

Merdusahead Hay

Choice between TF hay and medusahead at three stages of maturity

C HE HP CH0

20

40

60Trial 2- Mature and Hay Trial 3 – Thatch and Hay

Trial 1 - Seedhead Emergence and Hay

Crude Protein Silica0

2

4

6

8

10

12

Green MatureThatch

%Crude Protein and Silica Content of Medusahead

at Three Stages of Maturity

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

1 2 3 4 50

5

10

15

20

25

30

70

80

90

100

110

120 Silica added to Alfalfa

70

80

90

100

110

120

Alfalfa

2.5% Si

4.5% Si

1 2 3 4 50

5

10

15

20

25

30

Before adding Silica to Alfalfa

Tall Fescue Intake Before Adding Silica to Alfalfa

Tall Fescue Intake After Adding Silica to Alfalfa

Inta

ke (g

/kg

0.75

)

Is Medusahead Aversive?

Fed coconut-flavored beet pulp

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)

Then they received intraruminal infusions of:

1-Jul 2-Jul 3-Jul0

5

10

15

20

25

HayLiClMedusaheadIn

take

, g/K

g0.7

5Is Medusahead Aversive?

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.

Questions?