I'm having trouble understanding the definition. It can be found here. Small section:
The Load Bias also called the Protocol Mask, is retained in the memory resident database referred to as the dynamic store on the data collector. The dynamic store uses the Load Bias value to inflate the load for the server during the client resolution phase until the true load value is received.
If a server is least loaded by a load value of 1000, a Load Bias of 100 decimal allows 10 connections to be resolved to that server before subsequent connections are balanced to the other servers. This is a temporary condition until the server sends the load update to the local data collector.