I believe you mean Mazuri
Mazuri "6F" is what most people feed their breeder rats. It's whats called a "Lab Block", which is a food designed to give breeding rats everything need to be top notch breeders, complete nutrition.
The two lab blocks brands I use are Mazuri 6F and the Native Earth 4018 (company is called Harlan), both are a 18% protein formula, which is what is recommended for breeders.
Now for finding/buying quality lab blocks you can go two ways.
1. You can find a local feed store, which usually sell 50lb bags of Mazuri 6F for about $30 a bag. To find a local feed store that carries Mazuri I recommend going to
Mazuri's homepage and entering your zip code in the
dealer locator and seeing if there is any place near you that either carries it or can order the 6f for you.
2. You can order Native Earth Lab block online from
National Pet Pharmacy, which is only $.53 a pound for one 40 pound bag or $.38 a pound for five 40 pound bags shipped to your door (tax free in most cases), compared to paying a typical $30 for a 50 pound bag or Mazuri 6F at your local feed store( .$60 a pound + sales tax and round trip gas).
After I discovered National Pet Pharmacy it's now where I get all my Lab Block from.