While leading cows with wheat in hand, cows can't jump up 1 high blocks. Cows can climb up "half blocks" (placed fence post in ground to provide step-up) while being lead. Under normal actions cows can climb as normal.
Biome: Forest.
survival mode, world started in 14w30c.
Environment
Win7-64bit, Java 7-update 5 (build 1.7.0_05-b06). System specs: i7 proc, 8 GB ram, 1TB HD, Laptop.
Dupe of MC-64497