Re: Maternal Genetic effects in ASReml-R

From: Jarrod Hadfield <J.Hadfield_at_ED.AC.UK>
Date: Thu, 31 Jan 2008 19:52:30 +0000

Dear Brian,

Thanks for the quick reply. I haven't been able to get correlated
random effects using "link" yet (I get various error messages), but
I'm not sure I've specified ASReml-R to fit the simpler model correctly.

I am using simulated data in order to test the power of different
designs for estimating maternal genetic effects, and I'm reasonably
confident that the design I have allows me to separate additive
genetic, maternal additive genetic and maternal environment effects.
However when I fit the model the maternal environment effect is
constrained at zero. The estimate of the additive genetic variance
seems to be unbiased but the estimate of the maternal genetic
variance is equal to the total maternal variance (genetic + maternal):

The model I fit is:

asreml(y~1, random=~nurse+ped(id, var=T)+ped(nurse, var=T), ginverse
(id=Gped, nurse=Gped))

but the estimates suggest that nurse and ped(nurse, var=T) are
fitting the same thing (allthough they are not).

The replicates consist of 4 pairs of sisters mated to 8 unrelated
males to form 8 parental pairs. Each of the 8 parental pairs then
produce 4 offspring. The 8 parental pairs are then organised into 4
dyads where the 2 pairs making up the dyad are unrelated to each
other. 1/2 of the offspring for each pair are reared by the other
parental parents within the dyad. Offspring are therefore raised by
nurses, which in 50% of cases are also their dams. In addition the
dyads are formed so that a sister pair are not paired with
individuals that are also sisters. Hence, I'm reasonably confident
the effects can be estimated since unrelated offspring are reared by
sisters (maternal genetic effects), unrelated offspring are reared by
the same nurse (maternal environmental effects) and related offspring
are reared by their mothers and unrelated nurses (additive genetic

Perhaps I'm mistaken?


On 30 Jan 2008, at 17:20, brian.cullis_at_DPI.NSW.GOV.AU wrote:

> Dear jarrod
> I have to admit that I have never fitted these but I would imagine
> that you could as shown in the ASReml-R manual page 58 section 5.4.
> As for correlating additive and maternal I would think this is also
> possible using us(link(~ped(Calf) + ped(Dam))) but I dont think
> this has been tested or requested. Hence I am ccing this to David
> Butler, the author of ASReml-R to check the syntax and the use of
> ped() within link()
> Arthur and I are in the UK at the moment and so DBs response will
> be in Oz time
> warm regards
> Brian Cullis
> Research Leader, Biometrics &
> Senior Principal Research Scientist
> NSW Department of Primary Industries
> Wagga Wagga Agricultural Institute
> Professor,
> Faculty of Agriculture, Food & Natural Resources
> The University of Sydney
> Phone: 61 2 6938 1855
> Fax: 61 2 6938 1809
> Mobile: 0439 448 591
> Jarrod Hadfield <J.Hadfield_at_ED.AC.UK>
> Sent by: ASReml users discussion group <ASREML-L_at_AGRIC.NSW.GOV.AU>
> 31/01/2008 04:02 AM
> Please respond to
> ASReml users discussion group <ASREML-L_at_AGRIC.NSW.GOV.AU>
> To
> cc
> Subject
> Maternal Genetic effects in ASReml-R
> Hi Everyone,
> Is it possible to fit maternal genetic effects in ASReml-R yet? If
> so does any one have any example code they could show me (preferably
> with the covariance between additive and maternal genetic effects
> estimated)?
> Thanks,
> Jarrod
Received on Sun Jan 31 2008 - 19:52:30 EST

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