http://www.fao.org/documents/card/en/c/28b6bd62-5433-4fad-b5a1-8ac61eb671b1/ FAO Second International Technical Seminar/Workshop on Acute hepatopancreatic necrosis disease (AHPND) There is a way forward! FAO Technical Cooperation Programme: TCP/INT/3501 and TCP/INT/3502.

1. Heritability, crossbreeding
and inbreeding effects on
resistance of Penaeus
vannamei shrimp to AHPND
and WSSV in Mexico
Héctor Castillo-Juárez
Universidad Autónoma Metropolitana
hcjuarez@correo.xoc.uam.mx

2. Background
Mexican shrimp farmers have been facing
AHPND and WSSV during the last few
years.
Farmers have moved to grow Ecuadorian
lines (low growth but better survival rates
to AHPND and WSSV than Mexican lines).
Mexican line dropped demand (high
growth but susceptible to these diseases).

3. Background
A genetic line resistant to AHPND and
WSSV is being developed by 3 Mexican
research institutions and a Mexican
hatchery.
* Maricultura del Pacífico SA de CV
* Universidad Autónoma Metropolitana.
* Universidad Nacional Autónoma de
México.
* CIAD, Sinaloa, México.

4. Experimental studies aimed to yield
diseases resistance genetic line.
• Results from 2014 were presented in
Panama 2015 workshop.
• I am presenting results from 2015
experiments.
• Experiments for the 2016 cycle are
running now.

5. Disease Challenge Unit
Facilities designed to evaluate genetic
disease resistance
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Surviving
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Label

6. Objective of 2015 study
• Estimate heritability, crossbreeding,
and inbreeding effects for survival time
in the test (challenge).
• Compare genetic lines and their
crosses for resistance to AHPND and
WSSV.

7. Data population structure
• Ecuadorian line with history of WSSV
resistance.
• Mexican line with high growth ability.
• Crosses between these lines (F1 and
backcrosses).
• Inbred animals (2.7 to 25%) from F1
and from Ecuadorian families.

8. AHPND trial
• 5,171 animals
• 182 sib families (119 sires).
• Initial age: 75.7 days
• Initial body weight: 2.63 g
• 6 tanks (during 74 hours).
• Vibrio parahemolyticus strain M0904 at
3.2 x 105 CFU/mL.

9. WSSV trial
• 6,231 animals
• 181 sib families (118 sires).
• Initial age: 89.7 days
• Initial body weight: 4.23 g
• 6 tanks (during 144 hours).
• Per os infestation (dose: 107 copies of
infective viral DNA/g).

10. Quantitative genetic analysis
• Multiple trait mixed animal model.
• Additive genetic direct and maternal
effects / full-sib common environmental
effects.
• Crossbreeding (direct, maternal, and
heterosis) and inbreeding effects.
• Tank and initial age as fixed effects.

11. Comparing lines

12. Genetic parameters

13. Conclusions
• There is additive direct genetic variation
for AHPND resistance.
• Additive genetic maternal effects for
AHPND and their negative genetic
correlation with additive direct effects
should be considered in breeding
programs.

14. Conclusions
• There were no inbreeding effects for
AHPND.
• There were no differences between
genetic lines or their crosses for
AHPND.

15. Conclusions
• There is additive direct genetic variation
for WSSV resistance.
• There were crossbreeding and heterosis
effects for WSSV.
• The heterosis effect was negative, with F1
performance closer to the Mexican line
(suggesting a recesive gene involved).

16. Conclusions
• There were no inbreeding effects for
WSSV.
• There were differences in favor of the
Ecuadorian line compared to the
Mexican line for WSSV.

17. Conclusions
• Genetic effects for AHPND and WSSV
resistance were independent.
• It is possible to develop lines of shrimp
with greater genetic resistance to these
diseases using both selection and
crossbreeding.

18. Thank you