I am quite certain that the prisoners from the 153 PA Infantry were rounded up by the 5 NC Infantry on May 2, 1863. Their battlefield locations indicate that these regiments were directly involved on that day. On May 3, 1863, the 153 PA was part of the Union XI Corps that remained unorganized in a reserve position behind Hooker's line.

As to the 5 NC Cavalry, I can find no reference to their involvement at the battle. There may be a report of their activities at that time in the Official Records. These records should be found near the following:

http://ebooks.library.cornell.edu/cgi/t/text/pageviewer-idx?c=moawar;cc=moawar;q1=Rodes;rgn=full%20text;idno=waro0039;didno=waro0039;view=image;seq=972;page=root;size=100