Dear Philip,

If your intestinal contents are faeces than just freeze it in -80 deg. centri. Use clean eppedorf. No need to add anything. it will work fine to perform DNA extraction. You can do DNA extraction immediately also. Just to follow same procedures for all of your samples.

Dear Philip, I don't think that it is for RNA analysis so...if the aim is for DNA analysis, as Mamun say, just freeze the sample.

When I was on the field, I added ethanol in faecal mix, and when came back to the lab, I put it in the freezer!