1. 2006 SARE Group Farmer/Rancher Grant
Selecting Sheep for Parasite Resistance
SARE Project Number: FNC05-583
Kathy Bielek
Misty Oaks Farm
1130 Kimber Road
Wooster, OH

2. Outline The Parasite Problem Background 2006 SARE Producer Grant
Selecting Sheep for Parasite Resistance
Questions & Answers

3. Courtesy of William Shulaw, DVM, MS

4. The Parasite Problem
Parasites affect the health and productivity of sheep
Reduced lamb growth
Potential death of lambs and ewes
Require expensive chemical dewormers
Most susceptible are lambs & lactating ewes
Parasites are developing resistance to dewormers

5. RESISTANCE SELECTION IN ADULT WORMS
TREATMENT
Courtesy of William Shulaw, DVM, MS

6. Why Selection Works
Parasite numbers not evenly distributed among all animals in flock
Roughly 20% of animals harbor 80% of parasites
Treating only those 20% helps avoid developing parasites resistant to dewormers
Identifying and selecting less susceptible replacement animals will help increase flock’s resistance to parasites over time

7. 103,546,200 eggs per day for just 46 sheep
Fall 2000
103,546,200 eggs per day for just 46 sheep
Just 10 (21%) of the lambs excreted 77% of the eggs !!

8. 17,300 epg
150 epg
650 epg
1850 epg
2450 epg
600 epg

9. Misty Oaks Farm
Our current grant had it’s start in work we did on our farm through a Warner grant in 2004, and then an individual SARE producer grant in In both years we worked with Dr. Shulaw, and selectively dewormed and monitored fecal egg counts weekly through the spring and summer.
At the end of the first summer, we looked at the average FEC of lambs from each sire, and saw some drastic differences. As you can see, lambs from this ram (Ram C) had some pretty high counts, and every one required deworming. This ram (Ram A) on the other hand, had lambs with consistently low counts, and none ever required deworming.
This gave us the idea to identify sires with ability to pass on increased resistance to parasites. Several other Katahdin breeders were also interested, which led us to the 2006 SARE farmer/rancher grant.

10. Participants Total of 456 lambs and 31 rams in project
Jeff & Kathy Bielek - Misty Oaks Farm - Ohio
David Coplen - Birch Cove Farm - Missouri
Doug & Mary Emrick - Lazydae Farm - Ohio
Richard Gilbert - Mossy Dell Farm - Ohio
Naomi & Dean Hawkins - Green Pastures Farm - Ohio
Sue & Dave Ingram - DSI Katahdins - Missouri
Leah Miller - Bluebird Hill Farm - Ohio
Jim Orr - Orr Farm - Ohio
Bill Pope - Ohio
Donna & Doug Stoneback - Wade Jean Farm - Pennsylvania
Here is the list of farmers on the grant. There were 10 of us from three states: Ohio (7) Missouri (2) and Pennsylvania (1)
Nine producers raise Katahdin Hair Sheep; one used Katahdin ram on mixed Dorset ewes
Flock sizes range from 11 to 900+ ewes
7 Registered and 3 commercial flocks
We ended up with a total of 456 lambs and 31 rams in the project!
Total of 456 lambs and 31 rams in project

11. Katahdins: The Low Maintenance Meat Sheep
Excellent mothers
No shearing
Medium size
200% lamb crop
Single purpose: Meat
Natural parasite resistance

12. Our Collaborators New Cooperator
William Shulaw, DVM, MS
Extension Veterinarian, Beef/Sheep
Ohio State University
Charles Parker, PhD
Professor Emeritus, Dept of Animal Science
New Cooperator
David Notter, PhD
Professor of Animal Science
Virginia Tech
Dr. Notter directs the National Sheep Improvement Program (NSIP) Genetic Evaluation Center at Virginia Tech

13. Objectives of The Grant
Identify rams with ability to transmit parasite resistance to offspring
Compare effect of different management systems
Investigate method to identify potential replacement seed stock
Tools
FAMACHA
Body Condition Scoring (BCS)
Vigor Scoring
Fecal Egg Counts (FEC)
Our objectives on this grant were first to identify rams with the ability to sire lambs with increased parasite resistance.
Although we all raise Katahdins and are forage based, there are many differences in management. This became more apparent as we went along.

14. The FAMACHA© System
Compare eye color chart with color of mucous membranes of sheep
1 – not anemic
5 -- severely anemic
Eye color is an indirect measure of the worm burden – applies to Hemonchus contortus only
How many people are familiar with FAMACHA?
FAMACHA is a way of determining the level of parasite-induced anemia in sheep and lambs by looking at the mucus membranes of the lower eyelid. It was developed in South Africa.
Courtesy of William Shulaw, DVM, MS

15. FAMACHA – How it Works

16. Fecal egg counts (FEC) using McMaster Technique 1 egg = 50 epg

17. Method All lambs identified by sire
All lambs managed together in single group on each farm
FEC, FAMACHA & BCS done twice: at 8-10 weeks & weeks
No changes made to management of each farm

18. Detailed Record Keeping
Collected on all 456 lambs:
Lamb ID
Date of birth
Sex
Birth type & rearing
Birth weight
Sire ID
Dam ID
Age of Dam
Deworming history
Collected at least twice (8-10 and weeks of age; some at weeks) on 15 lambs per sire:
Date
Weight
Body condition score
FAMACHA
Vigor score
Fecal egg count

19. Results
Identified several rams that APPEAR to show greater ability to transmit parasite resistance to offspring
Management practices had major impact
Time of lambing
Pasture management
All farms able to identify potential replacement ewe and ram lambs

20. Adequate Numbers Are Necessary for Valid Comparisons
Avg = 1605 epg
Avg = 3280 epg
Avg Ram A
In any type of selection, you really need enough animals to make valid comparisons. 10 is the minimum, and 15 is ideal. Using more than 15 doesn’t seem to affect accuracy.
Avg Ram A

21. Management Example: Pasture Management Matters
Farm #1
All dewormed 7/20/06
Rotated across previously grazed pastures
Farm #2
All dewormed 7/16/06
Moved to clean pasture every week

22. Management Example: Pasture Conditions Can Change Quickly

23. Management Example: Nutrition
Singles in both cases have lower counts, probably at least in part because they had more milk The triplets tend to have higher counts than singles or twins. A twin out of a 4 year old (#612) has lower counts than a twin out of a yearling (#646 or #616)
Ram lambs seem to have more challenge than ewe lambs.
The same principle applies to ewes, especially during lactation.

24. Management Example: Time of Lambing
At 2nd collection (13 weeks of age):
older and heavier lambs had lower FEC.
a 10 day increase in lamb age resulted in 21% decrease in FEC.
a 10 pound increase in lamb weight resulted in 18% decrease in FEC.
Dr. Notter found that at 13 weeks of age, for every 10 lb increase in a lamb’s weight there was an associated decline in FEC of 21%!! Remember, this is in Katahdin lambs. Wool breeds typically develop resistance somewhat later.

25. Probable Sire Differences
Offspring of Sire A probably show more parasite resistance than Sire B.
But, dams of Sire B offspring mainly ewes lambing as yearlings – confounds results.

26. Selecting Parasite Resistant Service Sires Based on FEC
Be sure there is a challenge
Group average FEC of 1000 epg or higher
Compare adequate numbers
15-25 animals
Compare at least 2 sires
Compare apples to apples:
Same age
Similar management
Similar dam age, litter size, etc.
Calculate average FEC of all lambs from each sire
Choose sire with lowest average progeny FEC

27. Selecting Parasite Resistant Replacement Animals
Be sure there is a challenge
Group average FEC of 1000 epg or higher
Compare adequate numbers
15-25 animals
Compare apples to apples:
Same age
Similar management
Similar dam age, litter size, etc.
Choose lambs from sire with lowest average progeny FEC if more than 1 sire
Choose animals with lowest FECs in group
At least 2 FECs at different dates increases accuracy

28. Replacement Animal Selection
Note that #7172 and #7178 are low, but are raised as single – assume better nutrition. #7173 is a twin born and raised and shows evidence of self cure. I like that. Also, #7177 appears better than #7176 – self cure versus slow increase.
What about Ram B? (#7185 might be my choice – 2/2,shows evidence of self cure. #7182 and #7181 might be ok – both singles out of yearlings)

29. SARE Project Conclusions: Dr. Notter’s Comments
Selection favoring low FEC will be effective in increasing parasite resistance in Katahdin flocks. Heritability estimate = 0.52.
Age at measurement likely less important than level of infection at time of data collection.
Selection on FAMACHA scores on older lambs effective, but likely to produce considerably slower changes than direct FEC measurement and selection.
A combination of recording FAMACHA scores to monitor levels of parasite infection and recording FEC as selection tool may be optimal strategy to improve genetic resistance to internal parasites.

30. Avoid Single Trait Selection: We select for both low FEC and high productivity

31. Resources Southern Consortium for Small Ruminant Parasite Control
Maryland Small Ruminant Page
ATTRA (Appropriate Technology Transfer for Rural Areas)
Katahdin Hair Sheep International
khsi.org