Kagavi liked the “I” sweater or jersey worn by the son, Wayne Frake, in the 1945 Rogers and Hammerstein version of the movie State Fair.
I don't know whether it was official ISU wear, but before, Kagavi thought it possible that someone just called Iowa State up and had it shipped, rather than the studio making it in-house. The color scheme is interesting and includes grey elbow reinforcements. Per a comment I saw last year on YouTube, the color in the film won't degrade or change much if at all as it was filmed in (expensive) technicolor. So the colors should still be true and match the originals.
Sorry, but I am not certain how to link to a particular point in the film via my phone. You can see Wayne in the sweater at the following points, with the biggest shots of it towards the end of the first segment, and at the beginning of the second:
11.20 - 12:40
14:25 or so