masterThesis
Estimação de parâmetros genéticos para resistência à infecção por IMNV em camarões Litopenaeus vannamei por meio de análise de sobrevivência
Fecha
2013-06-19Registro en:
KURKJIAN, Karin. Estimation of genetic parameters for resistance to infection by IMNV in shrimp Litopenaeus vannamei through survival analysis. 2013. 79 f. Dissertação (Mestrado em Sistemas de Produção Sustentáveis no Semi-árido; Caracterização, conservação e melhoramento genético) - Universidade Federal do Rio Grande do Norte, Natal, 2013.
Autor
Kurkjian, Karin
Resumen
The main specie of marine shrimp raised at Brazil and in the world is Litopenaeus vannamei,
which had arrived in Brazil in the `80s. However, the entry of infectious myonecrosis virus
(IMNV), causing the infectious myonecrosis disease in marine shrimps, brought economic
losses to the national shrimp farming, with up to 70% of mortality in the shrimp production.
In this way, the objective was to evaluate the survival of shrimps Litopenaeus vannamei
infected with IMNV using the non parametric estimator of Kaplan-Meier and a model of
frailty for grouped data. It were conducted three tests of viral challenges lasting 20 days each,
at different periods of the year, keeping the parameters of pH, temperature, oxygen and
ammonia monitored daily. It was evaluated 60 full-sib families of L. vannamei infected by
IMNV in each viral challenge. The confirmation of the infection by IMNV was performed
using the technique of PCR in real time through Sybr Green dye. Using the Kaplan-Meier
estimator it was possible to detect significant differences (p <0.0001) between the survival
curves of families and tanks and also in the joint analysis between viral challenges. It were
estimated in each challenge, genetic parameters such as genetic value of family, it`s respective
rate risk (frailty), and heritability in the logarithmic scale through the frailty model for
grouped data. The heritability estimates were respectively 0.59; 0.36; and 0.59 in the viral
challenges 1; 2; and 3, and it was also possible to identify families that have lower and higher
rates of risk for the disease. These results can be used for selecting families more resistant to
the IMNV infection and to include characteristic of disease resistance in L. vannamei into the
genetic improvement programs