Kale isn't the best greens to give, certainly not as a stable. Though very rich in calcium, Kale also has oxilates which bind calcium, making it unusuable. Not as bad as spinach though. I would suggest mixing several stable greens with other vegies and greens, as a variety. With more choices, the dragon will be more likely to eat sufficient healthy greens. I think I mentioned this in my reply to your post last week, but just in case you missed it, check out the nutrition page at www.beautifuldragons.com
It has a list of many greens and vegetables (as well as fruit and flowers) that are both good and bad for dragons, with a color chart indicating frequency of feeding.
For dragons not used to eating greens or being stubburn about it, I suggest chopping them finely with a knife, mist them a bit so they are moist, then drop superworms or silkworms, giving them time to work under the greens. As the dragon roots and grabs the worms, they will get some greens and hopefully develop a taste for them. Bearded dragon pellets can also be sprinkled ontop of the salad as well. This works well for others but when I had a dragon, she would refuse to eat pellets and if they were on her salad, she wouldn't touch it at all. Picky little brat she was LOL. She ate salad fine when I put the silkworms into it though so that was good.
If your friend (the owner of the dragon) has internet access, give him a link to this site and deffinitely explain to him his dragon needs better care. As we don't know him, we can't really judge if he is neglecting the dragon or just had bad advise on it's care when he bought him. As he took the time to find a dragon sitter while he was away, this is something to me, indicates he cares enough about the dragon not to just leave him alone for two weeks. Given the fact many petstores (if that is where he bought the dragon originally) don't bother or know the proper care requirements of the reptiles they sell, he could have been badly misinformed on how to care for his dragon. There are petstores that have very knowledgeable employees who really do understand the care requirements for what they sell but these unfortunately, tend to be the exception more than the norm.
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PHLdyPayne