Matt a friend of mine got pork liver and his dog wouldn't even eat it. He gave me some to test and I couldn't get anything to hit on it. He got some lamb liver and it tested pretty good. I got a two part base that has deer liver and it's testing real good....???
That’s interesting because I’ve had decent luck with it, though I mostly use deer liver. I can remember reading a post on here where Asa said his coyotes wouldn’t touch beef liver. It would sit in their pen and rot. But they would snatch pork liver out of the air. I spoke with Clint Locklear one time on liver, and the addition of organ meat in general. His words were, “Don’t forget that liver is a filter, so those hog livers that Asa was feeding could have smelled a lot better than commercial livers, depending on what the hogs were being fed, or the overall condition of the hog when it was killed.” That statement is a good bit of the reason I generally stay with deer liver.
I’ve read several western studies that rated the attractiveness of pork liver higher than both beef and lamb liver, and stated that it was at least as effective as the best commercial lures. One of those studies also claimed that pork liver was the only meat tested that was found to be attractive to coyotes all year long.
Back to your bait base though… I think that even if the marrow doesn’t test out to be more attractive than some other bases, it could still prove to be a useful addition. I have my doubts that it will prove to be more attractive by itself than say, spoonbill oil, or catfish oil, or brains. But that doesn’t mean it won’t make a nice addition to your bait in combination with those bases. I have been grinding pork fat through my large plate and adding it to the last few baits I’ve made. I don’t know if coyotes are crazy over pork fat, but I do know that I really like the way it stiffens up a bait and lets you smear it where you want it. So maybe you don’t need to test it head to head against those other bases specifically. Perhaps you just need to test it in combination with something of known attraction. For example, the marrow doesn’t have to test better than the brains, if the addition of marrow to the brains tests better than the brains by themselves. Or, if the addition of the marrow to the brains makes the bait nicer to use and no less attractive, then it’s still a win. If you can stretch your rat glands with marrow, while also improving their usability, and not diminishing their attractiveness, again, it’s a win.
Just some random thoughts,
Matt