Flock!

for this achievement you must knock over 50 DIFFERENT pieces of fence with any cow. you won't unlock the cow levels until you complete level 7. you must complete a level for it to save how many you have done, however the achievement will pop before the end of a level once you reach 50 total. repeating the same level will not increase your score unless you do better. if you get all the pieces in a level, you need to play another level to get more.

level 8 has no cows. level 9 has 29 fence pieces. level 10 does not have any fence that you can access with a cow. level 11 has 15 fence pieces, and requires you to first place a cow on the arrow, then drop the other cow on the target to catapult the first cow across. level 12 has 24 pieces, and is pretty straightforward. that gives you 18 to spare so you will most likely get this just by playing those 3 levels even if you miss some. if not just replay those and take the time to hit each fence piece.

For this Achievement you must Knock Over 50 Fences With A Cow (Aggregate Total).

To do this this start up a level that has cows in it, which is a number of levels. Use your saucer to push the cows in the direction of any wooden fences and they will knock it over. You will then notice that you recieved points for doing this. If you didn't recieve points for the fence then it did not count. Keep in mind that there are two different kinds of fences as well as swinging gates in this game. I believe the ones you use to build a bridge do not count and the same with the swinging gate, obviously it's not a fence. Only the ones that are displayed in the achievement picture above are the ones you are after. Now the Knocked over 50 fences will be counted for the Achievement only upon completion of the level you are in. At least all the other achievements in this game are like that. Very easy Achievement.