Are these bugs alive or dead?
IF alive, they were likely not in the bag when you bought it.
If dead, then possibly, but you are going to have a tough time convincing the feed store or the manufacturer of that.
Because if they are alive, unless they can live in an environment without oxygen, then they weren't in the bag when you bought it because the bag/can/box is sealed and they would have suffocated eventually.
TIP: trash cans with lids are not a sealed environment and MANY insects can and do get into them. Even with the lid on, I've had ants, flies and spiders get into my trash. They crawl up under the lid. CERTAINLY, something as small as a weevil would have NO trouble getting into your can. The only thing a trash can will keep out is rodents..not insects. Your current system of storage isn't sufficient.
I also would not continue to feed my horses the infested bran. The insects themselves have not been identified and may or may not be poisonous to horses. Example: blister beetles which are found in hay ARE poisonous to horses and it doesn't take alot of them to sicken or kill your horse. PLUS, these insects are pooping in the horse feed, and their feces may have bacteria in it that may be toxic or upset the horses' delicate intestinal workings.
Last edited by Beauseant; 11-04-2011 at 08:39 AM.