[BioC] zero values and lib.size

[J [guest]]

I'm using the "classic" edgeR method and I was wondering if it is okay to add 0.5 to all of my tag counts before I do any processing of the data to make sure edgeR p-values and and logFC are not effected by any genes with 0 counts?  If this is okay, do I need to use these column sums as the new lib.size or since it would all be the same for every column would it be unnecessary? 

I'm referring to doing something like this…

all_counts <- all_counts + 0.5

then preceding with making the DGElist etc. 

Thanks

 -- output of sessionInfo(): 

R version 3.0.2 (2013-09-25)
Platform: x86_64-apple-darwin10.8.0 (64-bit)

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] splines   stats     graphics  grDevices utils     datasets  methods  
[8] base     

other attached packages:
[1] edgeR_3.4.2   limma_3.18.11

loaded via a namespace (and not attached):
[1] tools_3.0.2

--
Sent via the guest posting facility at bioconductor.org.