A lot of companies don't know that Facebook tailors what each of it's fans sees to how relevant it is for those individuals. The system of deciding who sees what is based on Facebook's EdgeRank algorithm which looks for three qualities: affinity, recency and interaction, and decides whether each fan should see your update.
It's really important for anyone actively engaged in Facebook marketing to fully understand this - or you might be wasting your time. If, for example, I rarely interact with your page, the chances are I won't see many of your updates at all. Given that even the top 10 brands on Facebook only interact regularly with 0.04% of their Fans, just have a guess at how many people actually see their updates? A company with 50,000 fans might , in fact, only be reaching a couple of hundred people with each update.
Facebook is understandably reluctant to share the magic formula behind Edgerank, but there are sites that claim to enable you to check your Edgerank. According to Edgerank Checker, you ought to be aiming for a score of 14+ to be above average. Obviously, the way to enhance your score is to post more frequently and interact regularly with your fans.
Be aware also that Facebook regularly tweaks Edgerank. Faced with an onslaught of newsfeed updates generated by game applications such as Cityville and Farmville, the network downgraded game updates, e.g. "Bob Smith has fed his chickens", to below the level required for publication to your friend's newsfeeds. This sensible change apparently led to dramatic fall in the retention of game-players who weren't reminded to feed their own virtual chickens.