Beef Protein should not have fillers in it. Most beef protein powders sold today have OTHER ingredients in them besides beef protein. Here is a list of those other things to look for and avoid.
1) Hydrolyzed gelatin (pork by product)
2) Hydrolyzed collagen (pork skin)
3) Glycine. Amino spiking ingredient
4) Tyrosine. Amino Spiking ingredient
5) Creatine. Spiking Ingredient.
6) Rice Protein. Not beef..duh.