Love me some Russian Folks...Tchaikovsky is my favorite, but give a stab at Rimsky-Korsakoff, Alexander Borodin (On the Steppes of Central Asia), Ippolitiv-Ivanov (Caucasian Sketches), Alexander Glazinoff, of course Rachminnov.Scarlatti, Bach, Sousa, Beethoven, Mozart, Bernstein, Tchaikovsky, Duke Ellington, Bacharach, Woody Guthrie, Gershwin...as long as it's relatively soothing and rhythmic, then I'm OK with it. Puccini gets a bit intense and so does Mozart.
It may be a bit lush, but you can also add Dvorak's Slavic Dances, Brahms' Hungarian Dances, Liszt Rhapsodies, Strauss Waltzes etc. I don't think the chickens will appreciate you trying to waltz with them with their wings held out for an extended period of time.
Throw some nice concerti in there, too. I try to avoid the string quartets and the like, because they can get a little freaky at times. The list is endless how you want to set a mood, whether more laid back or on the perky side to keep them entertained and scratching.
Sorry, I'm a Classical Fanatic. --BB