Game design wise I feel limiting the player's movement to only left and right would have been more interesting a challenge; this way you're forced to drop the cow if you don't time your abduction properly. I played the game at first like this before realizing I could go up and down which made things a little too easy. Some more enemy types or projectile variations would have been cool.
For a game made in 10 days with only the canvas API it was pretty good. The audio was lacking but the cute visuals made up for it.
Overall, it was a pretty neat experience. Simple and short but enjoyable.