Donkey Nutrition and Feeding: Nutrient Requirements and Recommended Allowances-A Review and Prospect

There are 44 million donkeys worldwide of which 95% are working. However, only limited research programs dedicated to donkeys are carried out in the world. Indeed, donkeys have a specific nutritional status. The donkey use a selective feeding strategy; when it is foraging either poor or good feedstuffs. The ingestibility of the diverse types of forages is different. Intake rate seems to be rather slow, whereas the mean retention time of feed residues in the digestive tract is very slow. As a result, the digestion coefficients of the chemical components of the feedstuffs are high, namely for the cell walls. The digestion coefficients increase when the donkey is fed restricted compared with ad libitum, and the mean retention time slows down. So far, the volatile fatty acids (VFA) production in the large intestine is very high. The donkey takes advantage of the very high N-recycling ability. The water intake is related to the type and amount of forage which is offered and the environmental conditions. The donkey is able to manage temporary water deprivation without too high limitation of intake. And, it is able to rehydrate quickly. Energy and protein requirements are much lower than those of other equids. Mineral and vitamin requirements are not yet established. One could expect that the key ratio between some minerals and vitamins as well should be met, but we do not know if there are any specific sparing mechanisms as there is for nitrogen. For rationing, there are some key tools that are available for estimating live weight and body condition and for predicting water consumption. But the intake capacity of resting and working donkeys is poorly described. However, there is no substitution between forages and concentrate when feeding mixed diets. Unfortunately, there are neither tables of nutritive value of feeds nor recommended daily nutrients and intake allowances for donkeys. Indeed, further investigation should be carried out in the scope of large cooperation.