Great post, Tom. I've been wanting to post something like this for some time.As a tortoise food, what's wrong with iceberg lettuce? Or other lettuce types too?
1. Too low in calcium.
2. Low Ca : P ratio.
3. Low fiber.
4. Low nutritional value.
Its everything a tortoise food should not be. Right? But what if we amend the lettuce? What if we mix in things to make up for these shortcomings and the lettuce serves as a delivery vehicle for these other items, along with the high water content of lettuce, all in a "package" that tortoises love?
As the size of my herd, and the size of the tortoises in my herd, have increased over the years, so to have my tortoise food needs increased. I used to be able to grow enough to feed them all, but with the drought, lack of time, and constant battles with the local wildlife eating my crops, I've had to start buying food. I still grow some of my own food, but its not enough anymore. I'm buying two cases of endive, escarole or romaine a week, and still have an opuntia day, Mazuri day, and either a mulberry or grapevine day. When I started feeding the grocery store greens, I was sure to add in what I call "amendments" to increase the fiber, calcium, and variety. For fiber, I soak Timothy hay horse pellets, These break down and I mix it with the lettuce in five gallon buckets, or large tubs. I use either type of ZooMed pellet for this purpose as well. Then I mix in some of @Kapidolo Farms dried leaf options. Moringa, dandelion, echinacea, marsh mallow, nettle, etc... Then I will add in some calcium powder. All of these things combined serve to make a good tortoise meal, and I've been getting by this way.
Here is the thing: I still need more and more food. I have some family friends that own a nearby restaurant. Every other day they cut up iceberg and romaine lettuce for burgers and salads, and this creates quite a lot of scrap pieces to be thrown away. Just their leavings make up about a 40 pound case, and they throw it in the dumpster because they have no use for it. This equates to about three full five gallon buckets which will feed my herd for a day. Its the heals and leaves they can't use. They sometimes offer it to me, but I've been reluctant because iceberg lettuce just is not a good thing to be feeding to my tortoises on a regular basis. Right? But what if I added chopped up orchard grass hay, soaked Timothy hay horse pellets, calcium, dried leaves, and I've recently started using Purina Organic Lay Crumbles for chickens on the advice of Will. Looking at the list above. Adding calcium carbonate powder fixes the low calcium and the Ca to P ratio. Adding the hay fixes the lack of fiber, and adding the lay crumbles and dried leaves fixes the low nutritional value part, right?
I've started feeding this lettuce with all this "stuff" mixed in a couple of days a week and it seems to be working fine. Poops are solid and full of rough fiber, growth is slow and steady each month, and my adults lay well formed eggs that hatch into vigorous healthy babies. I also mix in an assortment of other stuff when available too, like grated pumpkin, assorted other grocery greens like kale, collards, cilantro, spring mix, arugula, etc..., cucumber peels and various weeds, leaves and flowers.
I will agree with anyone that plain iceberg lettuce is not a good tortoise food to be fed in bulk on a regular basis, but when used as a vehicle to deliver all the good stuff that I am mixing in, it suits me fine. I welcome debate or conversation on the subject. Suggestions for improvement are welcome too.
I have been doing this - lettuce base to the meal - for years now. Just bite my tongue when I see references to NO LETTUCE here on the forum as did not want a debate.
Actually romaine and loose leaf lettuces are a very good food item. Loaded with many vitamins and minerals. As you mention, they lack enough fiber and romaine lacks enough calcium. Loose leaf lettuce actually has a good dalcium/phosphorus balance. I buy green leaf lettuce by the case each week as a base for many of the tortoise meals.
Here's a nutritional chart where I've selected a few of the evil lettuces and a few of the highly recommended items: (note how much vit A and C and low carb vs fiber lettuce is!)

Let's say we start with a pound of romaine and just look at the frequently mentioned poor calcium content vs phosphorus.
1 lb romaine = 163 mg calcium / 204mg Phos
We add 1/2 lb grape leaves. = 822mg cal / 206 Phos.
We chop up and mix into a nice salad that is now
1-1/4lb salad = 985mg cal / 410mg Phos
well over 2:1 cal/phos ratio in our salad.
But I mix in a lot of other things in a pound of lettuce. And normally at least an equal portion of grapes/mulberry/weeds to the lettuce for the day. Adding slices of cactus pads, lots of hibiscus and Rose of sharon flowers and leaves, etc, etc. The salad for the day is actually enhanced by the high vitamin and mineral content of the lettuce and the hydration of the great water content.
I will add I personally never use iceburg lettuce. But romaine and especially loose leaf is really a good added food.
As we always say - variety and lots if different food items is key. So whether we say these lettuces are good or not, we still can have those who will be lazy and only dwell on one food item. So the variety is key is the important part, not to eliminate lettuce as a choice of one of the items.
With Kapidolo Farms dried goods this also becomes easier. Without water content the dried items are about 10 times more dense in their vitamins and minerals. So my above example would only need just under 1 ounce of dried grape leaves to do the same thing! And the dried items stick to the lettuce mix and is impossible for the tortoise to eat anything without also eating the dried bits stuck to it!
Here's a typical salad for the day...
