Here's a few numbers for ya (there are a few repeats but I havent had time to shuffle through them yet):

Looks like 209 men of the 13th Louisiana took the Oath before the end of the war. Of that number 88 enlisted in US forces. This regiment was almost entirely from New Orleans and was loaded with several nationalities (lots of Irish). Looks like 114 deserters. Must take into consideration a few of these numbers are repeated in a few companies and several men deserted, took the oath and joined US forces. This is the first scan through.

Take the 25th Louisiana, though, from north Louisiana and the story is different. Not a whole lot of Irish or Germans in this group. Only 37 men took the Oath before the end of the war and of that number only 24 joined US forces. There were 98 deserters.

At the surrender in 1865 at Meridian looks like the 13th Louisiana had about 60 men present and the 25th Louisiana had 82.