I have to think it could be a few things:
1). Too much bone
2). Too much fiber (Psyllium husk)
3). Too much food in one serving (?)
As mentioned, too much bone would cause constipation. You can minimize the constipation by reducing bone from the whole carcass and see if that helps. That way, you can eliminate the addition of psyllium husk powder altogether. Watch Remy when he uses the litter box for any signs of straining while producing stools.
I also suspect you could be adding in too much PH fiber. Psyllium is a type of soluble fiber that adds water to the fecal content which ultimately with ends with bulkier stools. The extra-ordinary length he is producing makes me wonder if there could be more PH in there than he needs.
How much do you feed in one meal? Again, the amount of his solids produced sounds too much, so that's why I'm asking. Is that his normal size stools within a day? A typical active 10 lb cat should eat 5-6 oz per day. A sedentary cat, smaller cat, or one that is on a weight loss regime would require about 4 oz per day. I usually measure out portions by calculating the percentage of the cat's weight. Raw feeders go by 2-5% of their cat's ideal weight.
Anne's recipe is very much like Lisa Pierson's, but I think there's some details that she doesn't go into like Lisa does on her website. Here is what Lisa says (excerpted from catinfo.org on "Making Cat Food" regarding bone):
Taking a logical look at the calcium-to-phosphorus ratio (bone-to-meat ratio), it would seem that the easiest way to ensure having a proper ratio is to use a whole carcass of whatever animal you are choosing as a food source. However, after witnessing constipation in many raw-fed cats and watching lions strip the meat from the bones - leaving most of the bones behind - I am not comfortable feeding as much bone as that found in whole chickens, turkeys, or rabbits.
Therefore, I use poultry thighs, which have a lot of meat relative to the bone. I dilute the bone even further by removing ~25% of the thigh bones. If I am grinding 20 thighs, I remove 5 bones.
If you choose to grind up an entire carcass and not 'dilute' the bone with added boneless meat, then I would suggest at least leaving out the back and neck since these are the parts of the chicken/turkey with the highest bone-to-meat ratio.
On psyllium husk powder:
Start with 1/4 tsp once or twice daily and increase or decrease from there as needed.
Keep in mind that cats are not designed to handle a lot of fiber in their intestinal tract. The diet of a wild cat is very low in fiber. Horses and cows, on the other hand, are designed to eat very high fiber diets.
It is ok to add a little fiber to your cat's food but we don't want his poop looking like it came out of a St. Bernard!
There is one drawback to using fiber....you will no longer be able to brag that your cat's feces do not have any odor. The feces of a cat fed the recipe discussed on this webpage (without fiber) have very little odor but soluble fiber is fermented into some pretty stinky gases by the bacteria in the colon.
On the amount:
Most cats eat approximately 4-6 ounces/day but it depends on how much water you add to the recipe and how fatty the end result is. Fat has more calories than protein so it is more calorically dense.
This recipe yields enough food for one cat for approximately 10-14 days
Lisa uses 3 lbs of poultry thigh meat or 2.25 lbs of whole carcass ground rabbit + 0.75 lbs of boneless chicken or turkey (meat/fat/skin).