I did a quick look at the loaded stock cars running between Laramie and Rawlins, WY, in March/April 1949. The results are a bit surprising.
1. Of the 34 frt trains listed there were 10 trains carrying loaded stock cars.
2. All but one train is westbound.
3. There were 106 loaded stock cars located in 10 trains.
4. 34 stock cars were located in one train, 42 in another and 22 in another.
5. 8 cars were foreign, 98 were UP.
6.Foreign cars were 2 CB&Q, 1 CGW, 1 SP, 3 unknown [ #324, 325, 325 ] appear to have a 3 letter name beginning with "C", and 1 B&O.
7. Loads were 65 cattle, 15 hogs, 24 sheep, 2 horses.
8. Even though, in 1953, Omaha was the largest cattle market in the world [ according to a 1953 TV documentary Omaha: Rail Metropolis On The Plains produced by Mark I Video and, it contains a starting sequence with a 4-12-2 with actual sound ], all but one load is WESTBOUND.
9. The eastbound car is the B&O.