BrandonsBirbs
Thanks HopKat for my PFM ♥
Feedipedia looks like a fabulous resource, thank you!Two part answer. Maybe three part.
One) You have to understand what your bird's target diet is.
Two) You have to know what its getting from its complete feed
Three) you need a source of reliable (or at least consistent) information about the nutritional value of whatever you are feeding as a treat. Then you can calculate potential effects.
I start at Feedipedia.org. NOT because its right, but because its robust. Wait, its not right??? NOPE. Nor does it claim to be. Feedipedia uses averages* based on testing - and the problem with averages is that they tell you nothing about the individual ingredient you hold in your hand. But its free, its consistent, and its a start.
So, going to my favorite first source, and putting in "Cucumber", I find it has no information for that as a feed ingredient in its standard format tables. But it does mention this, "Performance and economical efficiency of growing New Zealand White rabbit fed cucumber (Cucumis sativus l.) vines straw without or with some feed additives under Egyptian conditions" That could be interesting. (Google search turns up nothing but an abstract. BAH!). There is also this, "Effects of replacing clover hay by cucumber (Cucumis sativus L.) vines straw without or with natuzyme or prebiotic" (same study, different author listed first - again, no hits).
Next, you can look to the USDA. Raw Cucumber. 95% water. 0.65% protein, 0.1% fat, 0.5% fiber. Not a significant source of calcium (16mg / 100g), not a useful source of pohosphorus (chickens can't use phytate, meaning plant-based, phosphorus). Some potassium, a tiny bit of selenium (micro grams, but chickens don't need much), and because the protein is so low, you can ignore the amino acid balance of that protein.
Basically, its flavored water with some fiber, some carbs, and some trace salts.
After that, its Google Scholar and start reading. (Mostly articles about using chicken manure/compost to feed cucumbers)
Simple. This is how I'm teaching myself.
*Feedipedia is better than many in that, after publishing the average, they also publish the max, the minimum, the standard deviation, and the number of samples tested - so if you see "6" or "3" or "1" for samples tested, you know the data isn't very reliable. And if you see an SD of 7.6 (look at Calcium), you know the presence of that component is highly variable.
So about:
93% water
0.03% protein
0.005% fat
<0.005% calcium
0.004% potassium
Seems like they will not affect diet very much! Glad I am not causing any issues just giving them some extra water!