I've found the terms "aspic" and of course "drippings" and "gravy", but I don't think any of those quite describe what I'm asking about — for example, we just baked some meatballs and between each one there was a mix of both liquid fat and a grey-ish/pink-ish sludge. With chicken meat it tends to be whiter. It has a texture somewhere between cooked liver and jello.  Is there a proper name for this "sludge"? Are there any particularly traditional uses for it?  UPDATE: another question calls this same thing "scum", and the answers deal with what it is: What's that scum at the sides of my home-made burger when I cook it?  I'm wondering here what it's called, i.e. if there's a more generous term for it than "sludge" or "scum". 
I just asked the exact same question here!: Why throw away so much sourdough starter? Tartine Book no. 3  I found a pretty good answer online. It actually would be easier and cheaper for you to throw it out, as you don't have to buy as much organic flour in the future to feed your starter. Imagine buying 5 cups each day to feed your starter when you could just use 100 grams!:     During the "initial" development - and by this I assume we're talking   the first several days of your brand spanking new starter, what you'll   be throwing away is likely not even "starter" but rather flour soup   wherein there's a fairly good chance you're also growing a few   less-than-desirable cohabitants. This would explain why you'd want to   chuck it out rather than use it.  You also cut back on your starter so   you don't end up with gallons of it since quite early on you do begin   to make your feeds at a ratio of 1:1:1 or 1:2:2.  For illustrative   purposes, let's follow the 1:2:2 ratio and just assume we're using   cups (easier to visualize) although you really would be weighing, of   course. So let's say  on day 1 morning feed, we begin with a half cup   of starter. Half a cup sounds like nearly nothing, right? To that we'd   then need to add twice that amount of each water and flour, so we add   1 cup water and 1 cup flour for a total of 2.5 cups. Still not that   bad. Day 1 evening feed, we're not reducing so we need to add to our   2.5 cups of starter 5 cups water and 5 cups flour for a total of 11 cups. Set it on the counter, hope it doesn't overflow everywhere and   go to bed. Day 2 morning feed, we're still not tossing away so to our   11 cups we have to add 22 cups of water and 22 cups of flour. We now   have 55 cups of starter or about 3.5 gallons. Remember, this is only   the third feed and we started with just a measly half cup yesterday   morning. At tonight's feed, we'll have 312 cups or 19.5 gallons of   starter. Just enough to fill up four of those white Home Depot buckets   although you'll want at least eight of 'em so the starter can double   in size. By morning of day three, you can fill your bathtub, if it   holds 97 gallons; it very well may not, and definitely won't hold the   expanded starter. By afternoon, you'll also be borrowing an additional   four neighbour's tubs for your 488 gallons.  How soon before you need   to move this out to a local swimming pool to continue? Well, by the   end of day five, you'd be the proud owner of 305,175.8 gallons of   starter. Or 4.8 million cups. Seriously. An Olympic size pool is about   600,000 gallons. By the morning of day six, you can fill two and a   half of them, with leftovers. And it hasn't even been a full week yet.   And that's why you cut your starter back down to a manageable amount   each time. It's a lot cheaper to toss a little bit out than to keep it   and feed it.   Source: http://www.thefreshloaf.com/node/12467/throw-away-half 