Estimating heritability with censored data

I would like to estimate the heritability of resistance to bacterial
infection in grower rabbits.

I have data on the weekly incidence of bacterial infection in grower
rabbits and mortality data (with post-mortem findings of bacterial
infection) that looks like this:

Rabbit wk5 wk6 wk7 wk8 wk9 wk10

1 0 0 0 0 1
1 rabbit healthy for first 4 weeks then sick but
alive for last two

2 1 dead dead dead dead
dead rabbit sick wk5 and dead by wk6

3 0 0 0 0 0
0 rabbit healthy and alive every week

4 0 0 0 dead dead
dead rabbit apparently healthy until wk8 when it was
dead

Is there a way of analysing this data in ASREML to account for the dead
animals?

Two suggestions have been:

1. multiple threshold model with more than two categories
2. animal model with repeated measures for each individual

but using the whole data set - live and dead animals. But I am not sure
this properly accounts for the missing data when an animal is dead.

Another suggestion is to define the trait as number of weeks "alive and
healthy" so that all animals have a complete dataset.

Any suggestions welcome!

Thanks,

Sandra

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Dr Sandra Eady

Stream Leader Integrated On-Farm Systems

CSIRO Livestock Industries

Private Mailbag 1

Armidale NSW 2350

Australia

Phone +61 2 6776 1394

Fax +61 2 6776 1371

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Received on Wed Jul 28 2006 - 16:43:47 EST