I never seem to have a farm animal stuck in love mode

I can think of 3 possible explanations:

  • You actually have an even number of cows. Or you missed a few and only fed an even number of them.
  • You have the particles effect disabled in your settings.
  • You have a gazillion of cows, and don't have enough time to find the one with the heart particles. "Love mode" only lasts for 30 seconds.

My bet would be on the first option. It's not true that every other time you should have an odd number of cows. For example:

  1. You feed 8 cows and get 4 baby cows.
  2. Now you have 12, and make 6 more.
  3. You have 18, so 9 more babies.
  4. Finally you have an odd number of cows, in your 4th time breeding them.

Have you checked how much wheat you spend in a whole feeding round? That would definitely tell you how many you fed. (Unless you go nuts, like I do, spam feeding them... then you may actually feed some of the babies too)