I am running a western blot using IgY as the sample to check for degradation. I am running both native and denatured samples, but I cannot get it to work. On the denatured, I get a large streaked band for the heavy chain, but when I lower the concentration, the light chain disappears. For the native, I get long streaks, but everything disappears when I lower the concentration. I am using 4-5% gel for native, and 10% for denatured. Since the sample is a primary antibody already, I am just using a secondary antibody at 1:5000. I have tried overnight and 1 hour incubation. I use ECL and film to visualize the bands. Any suggestions are greatly appreciated. 

How can I visualize both the heavy and light chains for Western Blot? - 

For visualizing both heavy and light chains use non-reducing gel (20%)

for viewing the chains separately use reducing gel (15-20%) or gradient gel. Gradient gels will give better results for your purpose.

You may use silver stain for western blots or if you are using secondary antibodies us (Fab')2 or (Fab) labelled secondary antibodies rather than constant Heavy chain binding secondaries.

I analyzed IgGs from different sources in native PAGE (10%). For hybridoma cell derived mAbs I obtain a distinct band but at different heights of the gel. For IgG purified from mouse serum I detected a broad/diffuse band. If I check the IgG from serum by size exclusion chromatography the molecular weight is fine, so I excluded degradation as cause for the diffuse band. I think a very heterogeneous glycosylation of the serum purified IgG is the reason for the diffuse bands and that mAbs from different hybridoma cell lines have a less heterogeneous glycosylation but the glycan composition differs between hybridoma cell lines. So using different antibodies as control for the native PAGE/Coomassie might help.

For the Western Blot, you can add more beta mercaptoethanol to ensure the complete dissociation of the antibody into heavy and light chains. How good the light chain or for examples different IgG subclasses are detectable is a mostly a feature of the distinct (polyclonal) secondary antibody or more precisely, of the immunogen which was used to generate it. So secondary antibodies against F(ab)2 or Fab may improve the detection of the light chain. You might just try different secondary antibodies and of course an IgY control would be great.

Could you specify your problem? Is it the streaks or the detection of light chains? Are you able to detect the light chains under denaturing conditions as long as you do not reduce concentration? In this case, your secondary antibody should be fine. Otherwise, you have to check for another one. An important point, which you probably considered, is the nature of your secondary antibody. To detect both, heavy and light chain, your secondary antibody needs to polyclonal, because you want to detect different epitopes.

Regarding your streaks under denaturing conditions, lowering the acrylamide concentration won't get rid of these. Streaks are indicative of an inhomogeneous sample. As Katrin already mentioned, this might be due to inhomogeneous glycosylation. Is your IgY of recombinant origin or purified from serum. If the latter is the case I would not be surprised by the streak, although I never tried to analyze primary immunoglobulins by Western blot. Otherwise, incomplete denaturation or possibly degradation, as already mentioned by Katrin and Jorg, may be the reason. Personally, I would try to separate the chains under reducing conditions using 12-15% Acrylamide.

It's could be possible, that an immunoglobulin has no light chains. We found it in several monoclonals loosing their antigen specificity. 

The detection was simple: SDS-pAGE (comparable conditions as you described), tank-blot onto nitrocelluloase, blocking, incubation with two conjugated anti-light-chain-antibody (AP labelled) and anti-heavy-chain-antibody (HRP-labelled) simultaneosly. Substrate reactions were carried out first for AP , than for HRP.  

We found: H2L2, H2L1, H2, H1L1, H1, L2, L1. Everythins was possible. 

But: I have no idea if anti-heavy and anti-L-chain antibodies are available for IgY...