I suspect that the suet hardness and lack of connective tissue and brown bits is actually a sign of good health. Some of the worst suet I've had was not 100% grassfed and yet was the most yellow I'd ever seen (it even said right on the package that they fed their animals all organic grain, which they were proud of--I'm guessing that yellow corn may have contributed to the yellowness, like it can in chicken eggs
http://www.npr.org/blogs/thesalt/2013/07/12/201501977/help-my-egg-yolks-are-freakishly-white). It was also softer, and more mealy, more like sawdust in the mouth, than the rock hard white deer suet and 100% grassfed suet, which was more waxy and tastier.
Yellowness does not guarantee 100% grassfed nor animal health, nor does whiteness guarantee grain fed nor ill health. I received confirmation of this from a 100% grassfed farm whose suet is the best I've tried in stores and is more white and harder than cheap grainfed supermarket suet, and posted about it before. For some reason, no one will believe this. The best tasting suet, with the best mouth feel, I've had was from a wild deer and was pure, solid white and rock hard, with no visible connective tissue or brown bits in it at all. I think I posted a photo of it.
I recall Lex suspecting that US Wellness farms meat was not truly 100% grassfed because the fat was less yellow than others. The owner was adamant that it is 100% grassfed, but it seemed that some folks wouldn't believe him because of this notion that yellowness=grassfed. I don't like their fat as much as the best fat in local markets, which is even less yellow than that of US Wellness, but what he said fit with everything else I've learned.
The more I think about it, the more it makes sense that the suet of healthy wild animals would be harder and purer, with less connective tissue in it, than that of grassfed domesticated animals. It fits with the general tendency for things to be in the wrong places in sickly animals and people--such as intramuscular fat in the muscles, tumors in the brain containing bone, teeth, hair, etc.--and with what I find to be softer muscle tissue in the lean portion of grainfed meats. I find grassfed and wild meats to be firmer, leaner and darker red, with less fat in the muscle and less connective tissue in the fat. Which would you rather have, fatty muscles and a soft midsection with soft perinephric fat ("suet") protecting the organs and a flabby belly, or lean, hard muscles and a rock-hard midsection that can take a punch?
Whiteness is probably also not a guarantee of quality and health, but so far I've been finding that the whiter the suet, the better. I know, I know, that's heresy on teh Interwebs.
