I use feather fixer in my ferment. I also use game bird grower pellets and some whole grains. It doesn't have a chance to get too fowl smelling. I remove some daily to feed out and add in more, fresh and stir it up. Doesn't smell too bad. Maybe that's because of all the other stuff I put in there.You make it. It's simple and easy. Get a big plastic pail and fill it halfway with warm water, add a couple glugs of ACV with the unfiltered "mother", some feed (whatever you normally feed your chickens), maybe some BOSS and some scratch grain, and mix it well. It should be soupy to begin with. It will absorb the water over the next 24 hours, and begin to ferment. It will start smelling like wine and will be the consistency of oatmeal. You can begin feeding it as soon as it starts sending up tiny bubbles.
Most people feed a half a cup of FF per chicken per day. Mine demand a little more than that. Usually that's all you need to feed them. For more info go look at Beekissed's thread on fermented feed on Feeding and Watering your Flock forum.
PS Do NOT use Feather Fixer in FF! It smells awful when it's fermented! But I'm glad it's working for you , Maurice!