According to the last price list I have handy, around here, in April, corn distillers was $6 for a 40# bag. Other mixed brewers spent grain was about the same. It is very commonly used as a cattle feed around here. The advertisement sounds like something similar. I would of course check it out very carefully, but if it is from a reputable source, would not have a problem feeding it as a protein supplement.
From Wikipedia
"Distillers Grains are a cereal byproduct of the distillation process.
There are two main sources of these grains. The traditional sources were from brewers. More recently, ethanol plants are a growing source. It is created in distilleries by drying mash, and is subsequently sold for a variety of purposes, usually as fodder for livestock (especially ruminants). Corn based distillers grains from the ethanol industry are commonly sold as a high protein livestock feed that increases efficiency and lowers the risk of subacute acidosis in beef cattle.[1]"
From Wikipedia
"Distillers Grains are a cereal byproduct of the distillation process.
There are two main sources of these grains. The traditional sources were from brewers. More recently, ethanol plants are a growing source. It is created in distilleries by drying mash, and is subsequently sold for a variety of purposes, usually as fodder for livestock (especially ruminants). Corn based distillers grains from the ethanol industry are commonly sold as a high protein livestock feed that increases efficiency and lowers the risk of subacute acidosis in beef cattle.[1]"
