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 44691
330-264-5281
bielek@bright.net
Outline

The Parasite Problem

Background

2006 SARE Producer Grant

Selecting Sheep for Parasite Resistance

Questions & Answers
Courtesy of William Shulaw, DVM, MS
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
RESISTANCE
SELECTION
IN ADULT
WORMS
TREATMENT
Courtesy of William Shulaw, DVM, MS
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
number of eggs
XXX Farm Daily Egg Output
Fall 2000
18000000
16000000
14000000
12000000
10000000
8000000
6000000
4000000
2000000
0
1
4
7 10 13 16 19 22 25 28 31 34 37 40 43 46
all sheep
103,546,200 eggs per
day for just 46 sheep
Just 10 (21%) of the lambs
excreted 77% of the eggs !!
150 epg
600 epg
1850 epg
650 epg
2450 epg
150 epg
17,300 epg
14
5/ /04
21
/
5/ 04
28
/0
6/ 4
4/
6/ 04
11
/
6/ 04
18
/
6/ 04
25
/0
7/ 4
1/
0
7/ 4
9/
7/ 04
16
/
7/ 04
23
/
7/ 04
30
/0
8/ 4
6/
8/ 04
13
/
8/ 04
20
/
8/ 04
27
/0
4
5/
EPG
Misty Oaks Farm - 2004
2004 Average FECs by Sire
Lambs Dewormed
4500
4000
3500
3000
2500
2000
1500
1000
500
0
A
B
C
D
Participants

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
Total of 456 lambs and 31 rams in project
Katahdins: The Low
Maintenance Meat Sheep

Excellent mothers

No shearing

Medium size

200% lamb crop

Single purpose: Meat

Natural parasite resistance
Our Collaborators
 William Shulaw, DVM, MS
Extension Veterinarian, Beef/Sheep
Ohio State University

Charles Parker, PhD
Professor Emeritus, Dept of Animal Science
Ohio State University
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
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)
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
Courtesy of William Shulaw, DVM, MS
FAMACHA – How
it Works
Fecal egg
counts (FEC)
using McMaster
Technique
1 egg = 50 epg
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 & 12-14 weeks

No changes made to management of
each farm
Detailed Record Keeping

Collected on all 456
lambs:

Collected at least twice
(8-10 and 12-14 weeks
of age; some at 16-18
weeks) on 15 lambs per
sire:

Lamb ID

Date of birth

Sex

Date

Birth type & rearing

Weight

Birth weight

Body condition score

Sire ID

FAMACHA

Dam ID

Vigor score

Age of Dam

Fecal egg count

Deworming history
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
Adequate Numbers Are Necessary for
Valid Comparisons
Lamb ID
DOB
7161
7162
7163
7164
7165
7166
7167
7168
7169
7170
7171
7172
7173
7174
7178
2/18/06
2/18/06
2/20/06
2/20/06
2/21/06
2/21/06
2/22/06
2/24/06
2/24/06
2/25/06
2/25/06
2/27/06
2/27/06
2/27/06
3/6/06
Sex
Born /
Reared
FEC
7/12/06
R
E
R
E
R
R
R
R
E
E
E
E
E
E
E
2/2
2/2
2/2
2/2
2/2
2/2
1/1
2/2
2/2
2/2
2/2
2/1
2/2
2/2
1/1
1850
450
300
650
450
450
950
9000
650
1300
9550
250
200
10150
300
2433
Avg Ram A
Avg Ram A
Avg = 1605 epg
Avg = 3280 epg
Management Example:
Pasture Management Matters

Farm #1

Farm #2

All dewormed 7/20/06

All dewormed 7/16/06

Rotated across previously
grazed pastures

Moved to clean pasture
every week
Farm #1 - 8/16/06
Lamb ID
Sire ID
603
612
613
616
638
639
640
641
645
646
Sire A Average
A
A
A
A
A
A
A
A
A
A
Farm #2 - 8/19/06
FAMACHA
FEC
3
3
1
3
2
3
3
3
3
3
3
300
0
250
1100
300
500
3450
1800
250
3150
1110
Lamb ID
Sire ID
11
14
46
5
10
49
6
24
29
3
Sire B Average
B
B
B
B
B
B
B
B
B
B
FAMACHA
FEC
2
2
1
1
1
1
3
2
2
2
2
0
0
0
50
0
0
50
0
150
0
25
Management Example:
Pasture Conditions Can Change Quickly
Lamb ID
Date of Birth
621
622
626
635
636
637
638
642
643
650
Average
3/18/06
3/18/06
3/20/06
3/26/06
3/26/06
3/27/06
3/27/06
3/27/06
3/27/06
3/30/06
FEC
FEC
FEC
5/21/06
150
100
100
50
300
150
50
0
150
100
115
6/28/06
1750
2550
1600
1300
4400
3000
1350
1400
1650
6050
2505
7/16/06
13700
10200
5100
15300
13650
11590
Management Example:
Nutrition
Lamb ID
DOB
Sex
Born/
Raised
603
616
645
646
606
640
641
652
612
613
661
662
663
638
639
664
671
672
4/17/06
4/19/06
4/26/06
4/26/06
4/17/06
4/25/06
4/25/06
4/28/06
4/19/06
4/19/06
4/29/06
4/29/06
4/29/06
4/24/06
4/24/06
4/30/06
5/1/06
5/1/06
R
R
E
R
E
E
R
E
E
E
E
R
E
E
R
R
R
R
1/1
2/2
2/2
2/2
1/1
2/2
2/2
2/2
2/2
2/2
3/3
3/3
3/3
2/2
2/2
2/2
2/2
2/2
Age of
Dam
16-Aug-06
FEC
1
1
1
1
2
2
2
3
4
4
4
4
4
5
5
6
8
8
300
1100
250
3150
0
3450
1800
450
0
250
50
2300
3750
300
500
550
300
500
Management Example:
Time of Lambing
Lamb ID
Date of Birth
Sire ID
FEC
6/28/06
1
2
9
10
13
14
17
18
7
12
2/14/06
2/14/06
2/23/06
2/24/06
2/26/06
2/28/06
3/2/06
3/2/06
2/22/06
2/26/06
Sire 1 Average
1
1
1
1
1
1
1
1
1
1
200
800
50
500
150
1400
1700
2950
350
950
905
26
35
36
37
38
42
43
49
50
51
3/20/06
3/26/06
3/26/06
3/27/06
3/27/06
3/27/06
3/27/06
3/30/06
3/30/06
3/30/06
Sire 2 Average
2
2
2
2
2
2
2
2
2
2
1600
1300
4400
3000
1350
1400
1650
450
6050
4450
2565
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.
Probable Sire Differences
Age of
Dam
FEC
6/12/06
FEC
7/12/06
A
A
A
A
A
A
A
A
A
A
A
A
2
3
2
2
3
2
2
3
3
3
4
150
1150
1600
7450
300
1100
2050
1100
250
3050
100
1664
450
950
1300
9550
250
200
10150
1050
550
500
300
2295
B
B
B
B
B
B
B
B
B
B
1
1
1
1
1
2
2
1
2
2350
100
2000
200
3000
650
1800
4500
4450
2117
8250
550
700
150
13900
2600
750
8150
10900
5106
Lamb ID
Sire ID
7162
7167
7170
7171
7172
7173
7174
7175
7176
7177
7178
7179
7180
7181
7182
7183
7184
7185
7186
7187
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.
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
Selecting Parasite Resistant
Replacement Animals

Be sure there is a challenge


Compare adequate numbers


Group average FEC of 1000 epg or higher
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
Replacement Animal Selection
Lamb ID
Sex
Birth /
Rearing
Sire ID
Age of
Dam
FEC
6/12/06
FEC
7/12/06
7162
7167
7170
7171
7172
7173
7174
7175
7176
7177
7178
E
R
E
E
E
E
E
E
E
E
E
2/2
1/1
2/2
2/2
2/1
2/2
2/2
3/3
3/3
3/3
1/1
A
A
A
A
A
A
A
A
A
A
A
A
2
3
2
2
3
2
2
3
3
3
4
Avg
150
1150
1600
7450
300
1100
2050
1100
250
3050
100
1664
450
950
1300
9550
250
200
10150
1050
550
500
300
2295
7179
7180
7181
7182
7183
7184
7185
7186
7187
R
E
E
E
E
R
E
E
R
2/2
2/2
1/1
1/1
1/1
2/2
2/2
1/1
1/1
B
B
B
B
B
B
B
B
B
B
1
1
1
1
1
2
2
1
2
Avg
2350
100
2000
200
3000
650
1800
4500
4450
2117
8250
550
700
150
13900
2600
750
8150
10900
5106
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.
Avoid Single Trait Selection: We select for
both low FEC and high productivity
2005 Ewe Production / Fecal Egg Count
Ew e Lambs show n in red; Number of lambs raised ( )
Average FEC During Lactation
2,500
( T w)
2,000
( T w)
( T w)
(S)
(S)
( T r)
( T w)
1,500
(S)
( T w)
1,000
( S)
( T r)
( S)
( T w)
500
( T w)
( T w)
( T w)
( T w)
0
0
20
40
60
80
100
120
Pounds of Lamb Weaned
(Adjusted Weights)
140
160
180
Resources

Southern Consortium for Small Ruminant
Parasite Control


Maryland Small Ruminant Page


http://www.sheepandgoat.com
ATTRA (Appropriate Technology Transfer for Rural Areas)


http://www.scsrpc.org
http://attra.org
Katahdin Hair Sheep International

http:// khsi.org