those recommendations have no basis whatsoever and are just a random assumption by various donkey websites, authors etc. The NRC recommends for donkeys and mules to stick as Dr. Kellon said to the numbers per kg that are available for horses. The NRC Nutrient Requirements for Horses contains a chapter on donkey and mule feeding that explains this.
Any other information out there sadly has no basis whatsoever, and I would rather steer clear of it. Quite a few of the folks out there balancing rations professionally have extensive experience with keeping donks on a balanced diet, with high success. :) So far my donkey has been on it for 2.5 years and thrives.
The Donkey Sanctuary UK is a good source of information mostly, but we have to take it with a grain of salt. They don't and likely cannot put their thousands of donkeys in their shelters on a balanced diet, so try to go with what is doable for them. They have not researched mineral requirements of donkeys and have just extended their recommendations from limiting energy and protein to limiting minerals, which frankly makes no sense.
Jennifer in Germany
Laramie July 2011
---In EquineCushings@..., <newleaffarm@...> wrote :
Thank you for your reply. I did not attend the 2nd Donkey Symposium held at UC Davis a month or so ago but heard that someone from the Donkey Sanctuary in UK stated 75% of horse minerals are appropriate for donkeys.