Training Lambs to be Weed-eaters

Experiments on the efficiency of Ovis airies for use in the biological control of Brachypodium sylvaticum- a

non-native bunchgrass

Ryan Scholz-Junior; Animal Sciences/ Bioresource Research

Dr. Howard Meyers-Professor; OSU Dept. Animal Sciences

Dr. Deborah Clark-Sr. Instructor; OSU Biology Program

Control

– Grazing• Observations at OSU

indicate grazing is effective

• Studies are underway to investigate this

– H. H. Meyer

• Relatively low palatability?

– Nutrition Tests

– Endophyte Tests

Grazed Un-Grazed

Planned Studies

• Pasture Training– Lambs to be grazed with mothers on B. sylvaticum

• Bummer Lamb Training– Bummer lambs to be fed B. sylvaticum

• Seed Viability• Nutritional Analysis

Pasture Training Study

Hypothesis

• Lambs grazed on B. sylvaticum with their mothers prior to weaning will have an increased affinity for B. sylvaticum as adults when compared to unexposed sheep.

Experimental Design

• Pre-Trial Training– Treatment- Grazed on B.

sylvaticum– Control- Grazed on

standard pasture– All lambs grazing for 3

week training period• First 2 weeks with ewes

• Last week weaned

Experimental Design

• Confinement Feeding Trial- wethers– Offered fresh cut B. sylvaticum after overnight fast– To determine the relative preference for B.

sylvaticum after training

• Pasture Grazing Trial- ewes– Grazed on a series of plots containing B. sylvaticum– To measure:

• Relative preference in a pasture setting• Continued preference over extended period of time

Confinement Feeding Trial

• Procedure– Lambs removed from field at 4:00pm and

individually penned– ~250g B. sylvaticum placed in each feeder at

10:00am• Allowed to eat for 30 minutes• Removed from pens• Leftover and wasted B. sylvaticum collected and weighed

– Repeated following morning

• Conducted immediately following training and again one month later

96%

4%

Data- Trial 1

Treatment Control

57%

22%

21%

Total Eaten Not Eaten Waste

100.0g B. sylvaticum

62%11%

27%

Data- Trial 2

Treatment Control

57%

22%

21%

Total Eaten Not Eaten Waste

250.0g B. sylvaticum

Analysis

• Shows training to be effective– Treatment lambs ate

more– Observations indicated

treatment lambs to be less timid when eating

• Some conditioning occurred with control– Likely situational

conditioning

Treatment

Control

Pasture Grazing Trial

• Procedure– Lambs grazed on series of 100m2 plots containing

B. sylvaticum– Four 1m2 clippings taken before and after grazing

• Determine biomass composition• Determine amount biomass removed

– Grazing patterns will be recorded using time-lapse video surveillance system

– Forage consumption and grazing patterns analyzed using forage maps

Data

Pasture Trial- Day 1

0.0

50.0

100.0

150.0

200.0

250.0

Treatment Control

Wei

gh

t (g

)

Beginning

Final

Analysis

• Final Analysis not complete– Observations indicate

training to be effective• Treatment lambs

consumed more B. sylvaticum

• Treatment lambs spent more time grazing

• Trial cut short due to uncontrollable circumstances

Further Planned Research

• Yearling trial– Ewe lambs will be kept– Pasture trial will be repeated with same lambs next

summer• Determine the continued preference over extended time

• Study replication

Bummer Lamb Study

Hypothesis

Orphan lambs which are fed milk replacer containing B. sylvaticum will have an increased affinity for B. sylvaticum as adults when compared to unexposed sheep.

Experimental Design

• Breeding/ lambing– 25 ewes given luteinizing hormone for estrus

synchronization, and bred– Labor induced using hormone treatment

• Lamb Care– Lambs divided into control and experimental groups– Experimental lambs receive milk replacer with B.

sylvaticum juice

• Confinement feeding trial– Lambs will undergo same confinement feeding trial

as pasture raised lambs.

Seed Viability Study

Hypothesis

• B. sylvaticum seeds digested and later deposited by Ovis airies will have a significantly diminished ability to germinate.

Experimental Design

• To determine the risk of further spread of B. sylvaticum through seeds deposited by sheep used for control.

• Two Trials– Forage Diet

• Sheep on forage diet to achieve similar ruminal micro biotic content as grazing sheep

– Concentrate Diet• To facilitate easy and accurate recovery of seeds from

feces

Experimental Design

• Ripe seeds collected and dried to ~10% moisture– B. sylcaticum– Loliium multiflorum (control)

• ~5 gram samples weighed to 1/10000g accuracy and sealed in Dacron digestion bags

• Samples inserted into rumen cannulas and allowed to digest for 72h, 48h, 24h, 12h– Control sample placed in water for 30m

Experimental Design

• After removal from rumen:– Samples washed thoroughly – Dried to ~10% moisture– Weighed to 1/10000g accuracy– Germinated in 25°C/15°C chamber

Data

• Average sample weight loss

0.0000

0.2000

0.4000

0.6000

0.8000

1.0000

1.2000

0h 12h 24h 48h 72h

Time

Weig

ht

(g)

B. sylvaticum L. multiflorum

Further Research

• Concentrate Diet Trial– Replication of Dacron bag procedure– 15g seed introduced directly into rumen

• Recovered from feces

• Further investigation into mode of digestion• Neutral/Acid Detergent Fiber tests

– Determine amount of carbohydrates digested

Nutritional Analysis

Purpose

• Proximate Nutritional analysis – Samples collected

throughout growth season – Allow grazing periods to

be planned to maximize :• Control of B. sylvaticum

• Nutritional benefits to sheep

Questions