Breeding for Resistance
to nfectious Diseases
in Small Ruminants
G.D. Gray, R.R. Woolaston
and B.T. Eaton
Breeding for Resistance to
Infectious Diseases in Small
Ruminants
G.D. Gray, R.R. Woolaston and B.T. Eaton
ACIAR
(Australian Centre for International Agricultural Research)
Canberra
AUSTRALIA
1995
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Preface
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Contents
Preface
iii
Contributors
ix
Genetic Variation in Resistance to Viruses
B. T. Eaton and GD. Gray
1
Host Cell Control of the Virus-Cell Interaction
Genetic Variation in Resistance of Mice to Virus Infection
Selection for Immune Responsiveness and Disease Resistance
Intracellular Immunisation and Genetic Engineering
References
Genetic Variation in Resistance to Bacteria
H. W. Raadsma
Bacterial Diseases of Potential Significance in Breeding Programs
Resistance and Potential Sources of Genetic Variation
Genetic Variation in Important Bacterial Diseases
Vaccine Responsiveness
Conclusion
References
Genetic Variation in Resistance to Parasites
G.D. Gray
Genetic Differences Between Hosts
Consequences of BreC"ding Nematode-resistant Sheep
References
3
5
9
11
12
15
16
19
21
32
35
36
43
43
45
51
Australian Research on Genetic Resistance to
Nematode Parasites
R.R. Woo/aston and S.I. Eady
53
Resistance and Resilience
Within-flock Variation in Resistance
CSIRO HoemoncAus Selection Flock
University of New England 'Golden Ram' flock
CSIRO TridlOstronglus Selection Lines
Armidale Nucleus Flock
Hamilton Selection Lines
Rylington Flock
Summary of Within-flock Variation
Between-flock Variation
Feasibility of a Breeding Program
References
53
55
55
56
59
61
61
63
63
64
70
74
iv
Breeding Sheep in New Zealand for Resistance or
Resilience to Nematode Parasites
c.A. Morris, T.G. Watson, S.A. Bisset, A. Vlassoff and
P.G.c. Douch
Genetic Parameters
Selection Experiments for Faecal Egg Counts
Selection for Resistance in Different Environments
Correlated Responses in Flocks Selected for Production
Studies on Resilience
Facial Eczema
Application in Commercial or Stud Sheep Flocks in New Zealand
Unresolved Issues and Possible Future Research Directions
References
Breeding for Resistance to Infectious Diseases of
Small Ruminants in Europe
L. Gruner and F. Lantier
Resistance to Parasites
Measurement of Resistance
Resistance to Infectious Diseases
Conclusions: the Main Topics Developed in Europe
References
Genetics of Disease Resistance in Small Ruminants
in Africa
R.L. Baker
Why Breed for Disease Resistance?
Economic Impact of Disease
Genetic Variation in Disease Resistance
Breeding Programs for Disease Resistance
Genetic Markers and Marker-assisted Selection
Concluding Comments
References
Genetic Variation in Resistance to Infectious Disease
in Small Ruminants in India
C. Nimbkar and B.V. Nimbkar
Sheep
Goats
Conclusions
References
77
79
83
87
88
89
91
91
94
95
99
101
102
107
112
113
119
120
120
122
127
129
130
130
139
140
145
149
149
Genetic Resistance to Infectious Disease in Small
Ruminants: North America and the Caribbean
A.M. Zajac
Genetic Resistance to Gastrointestinal Nematodes
Other Parasites
v
153
153
162
162
Other Diseases
Goats
Future Directions
References
163
163
164
Helminth Infections of Sheep in Rubber Plantations
in Sumatra
R.M. Gatenby, A./. Wilson, E. Romjali, V.S. Pandey,
L.P. Batubara and G.E. Bradford
Sheep and Management
Worm Burdens in Purebred and Crossbred Ewes
Total Worm Counts of Rams
Discussion
References
Studies on Genetic Resistance to Infectious
Diseases of Small Ruminants in Southeast Asia
V.S. Pandey
Malaysia
Indonesia
Thailand and the Philippines
General Remarks
References
168
168
169
169
170
173
174
175
176
176
177
Breeding to Assist Control of Gastrointestinal
Parasites of Small Ruminants in the Pacific Islands
R.R. Woolaston, P. Manueli, R. Singh, N. Tabunakawai
and L.F. Le lambre
Resistance in Goats
Resistance in Sheep
References
179
180
183
185
Phenotypic and Genetic Indicators of Resistance
to Ectopathogens
T.I. O'Meara and H.W. Raadsma
Phenotypic versus Genetic Indicators of Resistance
General Mechanisms of Resistance to Ectopathogens
Acquired Resistance to Ectopathogens
Systemic versus Local Immunity
Indicators for Resistance to Specific Ectopathogens
Dermatophilosis
Footrot
Ectoparasites excluding Diptera
Conclusion
References
vi
188
190
193
197
198
204
205
207
209
209
Phenotypic Traits Associated with Resistance to
Internal Parasites
S.I. Eady
Defining Resistance
Direct and Indirect Selection
Candidate Indicator Traits
Characteristics Required of Indicator Traits
Practical Requirements
Assessment of Resistance
Incorporating Disease Resistance into a Breeding Program
References
Genetic Markers for Disease Resistance
A.N. Blattman and K.I. Beh
DNA Markers
Hypervariable DNA Markers
Searches for Genetic Markers for Disease Resistance
Conclusion
References
Application of Genetic Markers
F.W. Nicholas and A.N. Blattman
Direct Selection for Resistance
The Moral Dilemma
The Nature of Disease Resistance in Small Ruminants
Markers
The Need for Genetic Maps
The Short-term Use of DNA Markers
Searching for Associations
Pitfalls in Searching for Markers
More Pitfalls
Conclusion
References
Incorporating Disease Resistance in Breeding Programs
S. Sivarajasingam
Why Select for Disease Resistance?
Relative Importance of Disease Resistance
Genetic Variation
Direct Response to Selection
Relationship with Production Traits
Selection for Disease Resistance
Breeding Program
Conclusions
References
vii
220
220
221
226
228
229
232
233
237
239
241
247
251
252
260
260
261
261
262
263
264
265
268
270
270
275
276
276
277
278
279
280
285
287
287
Methods of Using Genetic Variation-a Primer on
Selection, Nucleus Flocks, and Crossbreeding
B.P. Kinghorn
291
Selection
Crossbreeding
Choice of Crossing System
References
300
306
306
Assessing the Importance of Infectious and Non-infectious
Disease in Small Ruminants in Australia
D.B. Adams
Preliminary Considerations
The Nature and Spectrum of Disease
Assessment of Diseases
Importance of Sheep and Goats in Australia
Infectious Diseases
Diseases Caused by Metazoan Parasites
Non-infectious Diseases
Conclusions
References
viii
310
311
313
315
317
318
319
321
322