Feeding donkeys

A A Aganga, M Letso and A O Aganga*

Department of Animal Science and Production, Botswana College of Agriculture
Private Bag 0027, Gaborone, Botswana.
E-mail: aaganga@temo.bca.bw
*Department of Animal Health and Production, Ministry of Agriculture,
Private Bag 45, Lobatse, Botswana.

Abstract

Feeding is an important aspect in the management of any farm animal. It requires knowledge of the feeding behaviour and nutrient requirements of animals for specific production functions, e.g. work. The objective when feeding donkeys should be to make judicious use of available feed during times of deficit. This may be achieved by using the body condition scores of the donkeys as feeding guides or, where available, appropriate nutrient requirement data may be used.

In most practical considerations, donkey feeding is not as routine a management practice as for other farm animals. This is perhaps an indication of the economic value attached to donkeys or confidence in their resourcefulness when it comes to finding their own feed.

Key words: Donkeys, management, nutrition

Introduction

In arid and semi-arid areas, donkeys eat a wide variety of feeds. The donkeys graze, eat forbs and shrubs and the bark of trees. They normally should be allowed to graze for six to seven hours a day on free range. A donkey is a monogastric herbivore thus it eats roughages and utilizes cellulose and hemicellulose efficiently. A donkey that is not used all the time can find sufficient food on the range during the rainy season but may need to be offered supplementary feeds during the dry season or drought years. Donkeys graze successfully in most years when there is adequate rainfall and the animals remain in good body condition. When they are working regularly and the animals do not have adequate grazing time then owners must provide feed for the animals. Dry matter intake of the donkey is high compared with other large herbivores, being about 3.1 per cent of liveweight (Maloiy 1973). A general rule of thumb is that a donkey should be provided daily with straw or hay equal to 5% of its bodyweight, even though it may only eat about half of this (Jones 1997). Jones (1997) recommended that for a 200-300 kg donkey carrying 25-70 kg load at 4 km/hour, 6 hours/day, the diet should consist of 500g grain (coarsely ground maize or sorghum) and 2.5 kg chaff (by-product of dry cereal milling) or cowpea pods or peanut shells. She also suggested that some chaff could be replaced with hay or straw (dry grass). The ration should be given to the donkey in the morning, and then the same amount again in the evening.

Horse cubes are available in most countries for supplementary feed for horses, which donkeys actually enjoy. However, donkeys need more fibre and less protein in their diets than horses. Donkeys are different from horses in many ways, therefore they should not be fed like horses and they are not ruminants so they must not be fed like cattle, sheep or goats. For example urea may be poisonous to donkeys in large quantities. Therefore if donkeys have access to cattle lick with urea in the constituents, they must not consume too much to prevent urea poisoning.

Donkeys are grazers as well as browsers (Aganga and Tsopito 1998). The teeth and lips of donkeys permit them to graze close to the ground; thus they can graze short vegetation efficiently. Donkeys are non-selective grazers and can feed on a wide variety of foodstuffs, including kitchen leftovers.

Feeding behaviour

Feeding behaviour of donkeys is thought to be characterized by large intakes with low nutrient extraction. High rates of intake can be achieved by rapid chewing, large bites, effective chewing per bite, or sacrifice in particle size reduction (Mueller et al 1998). The donkey differs somewhat from the horse because its narrow muzzle and mobile lips promote greater selectivity in feeding. This allows it to maximize feed quality rather than quantity. The donkey may use a selective feeding strategy, searching for high quality bites when foraging over a heterogeneous pasture or rangeland, but when provided with homogenous hay employs an alternative strategy of maximizing intake. Mueller et al (1998) observed that, in practice, donkeys faced with some perceived need consume more food quickly, such as following an intentional or unintentional fast, or restricted time in which to eat due to insufficient feeder space, competition from herd mates or long hours spent working.  Under these conditions the donkey may resort not to faster chewing but to incomplete chewing. This, it was observed, could result in problems such as oesophageal obstruction (choke) and intestinal impaction. A donkey, which ate rapidly following a period of food restriction, was reported to suffer from oesophageal obstruction (Mueller et al 1998).

Chewing activity is an important aspect of feeding behaviour in donkeys. All herbivores, especially those that derive energy from microbial fermentation of fibre, must chew their food in order to prepare it for digestion. The donkey chews fragments of plant cells to reduce the feed particle size, promote salivary secretion and allow wetting of feed. The donkey (a non-ruminant herbivore) has only one opportunity during mastication to complete the physical processing of feed, unlike the ruminants that chew upon initial ingestion (mastication) and again during rumination. The amount of  time a donkey spends chewing a given amount of food is affected by a variety of factors, including the physiologic state, level of intake, amount of fibre in the diet, physical form of the feed, particle size of the feed and the health of the animal.

Physiological differences between the activities of the gastrointestinal tract of donkeys and that of ruminants are not readily apparent in spite of the obvious anatomical differences (Maloiy and Clemens 1980). The dry matter consistency of fore gut contents, the addition of fluids to the contents of the small intestines and the drying of the gut contents rearwards from the caecum to the rectum are all similar. Organic acid concentration in the upper (cranial) part of the donkey's stomach appears similar to that found in the rumen of ruminants although the volume of the gut fill is much smaller (Wilson 1990). In the donkey, the relative capacity of the stomach is 14 while that of caecum and colon is about 80: in ruminants the stomach has a relative capacity of about 80 and the caecum and colon about 13. In the donkey, microbial digestion occurs principally in the caecum and colon while in ruminants it takes place in the rumen. The stomach of ruminants and the large intestine of the donkey are therefore functionally similar (Wilson 1990).

Feeding guides

• Provide adequate clean, fresh water in clean watering troughs everyday.
• Feeding time and method should be consistent daily for the donkey.
• Feed donkeys intermittently with little food each time to prevent or minimise the risk of digestive upsets.
• Food provided should be free of foreign materials like plastic bags and any other materials (hardware), which might be dangerous to the donkey.
• A regularly working donkey with no adequate grazing time should be provided with some concentrate feeds to supplement its basal roughage diet.
• A donkey should be allowed a rest period after a very large feed.
• If necessary donkeys can be fitted with rope-mesh muzzle to stop them eating when they are working.
• Donkeys should be allowed to rest between long working hours. During the rest period, the animals should be offered water and a little feed. Many donkeys will not eat or drink when in harness. Therefore, it may be necessary to remove all harnessing depending on individual donkey's preferences.
• Donkeys should be fed to maintain body condition rather than to recover condition, which is more difficult, once it is lost.

Coprophagy

Coprophagy occurs in young donkeys which often eat the faeces of their dams within a few months of birth. This is viewed as a way for the young donkeys to obtain cellulose digesting bacteria and other microbes, which are abundant in the faeces. Adult, well-fed donkeys on a balanced diet, do not normally practice coprophagy. It occurs occasionally in housed donkeys that are bored and due to lack of stimulatory activities start to eat their own faeces. This is regarded as a behavioural disorder or bad habit.

Nutrient requirements

Water

Donkeys have lower water requirement per unit of weight than other domesticated animals, except the camel. Water intake of a donkey is influenced by the amount of work being done, the temperature and humidity of the environment, the dryness of the feed being consumed and the physiological status of the animal. Water requirement of a fully-grown adult donkey is in the range of 18 to 35 litres per day according to the above circumstances (Fielding and Krause 1998). Donkeys appear to feel less thirsty than other animals when exposed to water deprivation and may continue to eat when most animals, other than the camel, have stopped eating as a result of water shortage. Donkeys can withstand up to 20 - 25 percent weight loss due to dehydration and recover this loss when water becomes available. Dehydration in the thermo-neutral zone and at high ambient temperatures of 40ºC depresses food intake but apparently increases digestibility of ingested dry matter. Maloiy (1973) stated that intermittent changes in temperature, such as diurnal variation in air temperature of deserts, do not depress appetite providing water is not limited. Donkeys should be offered water at least once or preferably twice per day to ensure good functioning of their digestive system and provide oportunity for body water to evaporate, so maintaining body temperature.

Donkeys should not be offered very cold water when they are still hot from working. The water must be clean since donkeys may refuse to drink dirty water even when they need water (Jones 1997). Donkeys can go without water for up to 3 days without harm to the animal when there is water shortage.

Energy

Donkeys require less energy per unit of weight than cattle for walking which is due to skeletal differences, which make movement in equids more energy efficient. Digestible energy (DE) requirement of donkeys per unit of weight are about 75 percent those of horses and similar to those of ponies and small horses. DE requirement can be estimated at 465 W^0.75 KJ/day where W is the live weight of the donkey in kg. Therefore a donkey of 150 kg requires for maintenance 465*150^0.75 kJ of digestible energy = 19931 kJ or in practical terms 20 MJ (Fielding and Krause 1998). Energy requirement for work above maintenance is influenced by the size of the load, the slope of the land, the nature of the ground and the positioning and balancing of the load on the donkey. Energy requirements can be estimated from the energy costs of the different activities associated with work and knowledge of the amount of work done and distance traveled. Tables 1 and 2 show available data from Pearson et al (1995) on energy requirements of donkeys. Donkeys are able to digest high fibre forage diets and utilize organic acids for energy. Therefore, virtually all donkeys in Botswana are grazed or fed on straw and hay. The donkeys require the fibre to keep their digestive systems fully functional and to ensure a steady rate of food passage through the gut.

Table 1:  The energy costs of various activities associated with work in donkeys*
Observation	Location	Site	Energy cost	Source
Walking, J/m/kg liveweight	Tunisia	sandy/gravel tracks	1.37	Dijkman, pers.comm.
	Niger	laterite tracks	1.43	Pearson 1994
	USA	gravel roads	0.98	Youssef et al 1972
	UK	treadmill	0.97	Dijkman 1992
Carrying, J/m/kg carried	Tunisia	sandy/gravel tracks	1.8-2.3	Dijkman, pers. comm
	UK	treadmill	1.1	Dijkman 1992
Pulling, J/m/kg pulled	UK	treadmill	31.2	Pearson 1994
	UK	treadmill	26.5	Dijkman 1992
* Source: Pearson et al 1995

Protein

A donkey's protein requirement is influenced by the physiological status of the animal and what it is being required to do. Young growing donkeys and pregnant or lactating animals require more protein than mature, non-pregnant animals. Quality of protein fed to donkeys influences total daily protein requirement. Essential amino acids [EAA] are the amino acids which must be provided in the diets to the animal since it cannot synthesise the EAA by itself, or which cannot be synthesised by the bacteria in the digestive system in sufficient quantity to meet its requirements, for example methionine and lysine.

The donkey cannot store amino acids efficiently and therefore needs a constant supply in its diet. Legumes provide more of the essential amino acids than grasses and straws. Good feeding of donkeys with adequate protein supply can enable the animals to better resist disease challenge and improve the growth rate of growing donkeys. The challenge to the nutritionists is to develop recommendations on crude protein requirements for donkeys that can allow farmers to make economic decisions on feeding practices of the donkeys.

Minerals and vitamins

They are required for growth and development of the skeleton especially in growing donkeys. The skeleton is the load bearing structure for efficient working life, then this must be optimally developed and strong. Working donkeys need mineral supplements to replace the minerals lost in sweat. Donkeys should be provided with a mineral lick of a mixture of dicalcium phosphate and salt. The salt will replenish the sodium lost in sweat.

Feeds for donkeys

Donkeys should be fed hay or straws and legumes when available in the proportion of 4:1 straw to legume to appetite. Fresh legumes should not be fed as the only food. Also working donkeys should be given about 500 g of cereal bran per day.

Roughage

Donkeys are good grazers as well as browsers. Aganga and Tsopito (1998) stated that traditionally in Botswana donkeys that graze freely on rangeland throughout the year obtain enough roughage when they are not working. There is a wide range of grasses in the veld depending on location and season of the year. Some of the grasses available are Cenchrus ciliaris, Panicum maximum, Eragrostis superba and Aristida congesta. During the long dry season when the crude protein value of the grasses is low, and the quantity and quality of the grasses are poor, donkeys browse more. Donkeys at times peel the bark off of trees with their teeth when there is food scarcity, e.g. Boscia foetida and Acacia species (Aganga and Tsopito 1998). At times, some farmers feed their donkeys crop residues such as sorghum stover (dried stalks, leaves and heads without grains) and bran, maize stover and bran, cowpea husks and rejected water melon fruits. Roughage fed to donkeys should not always be rejects or poor quality. When possible, straw should be collected after harvest and stored in a dry shaded place for dry season feeding. Straw should be fed in dry clean troughs or containers to minimise wastage and contamination with dirt and faeces.

Concentrates

Protein can be supplied to donkeys by offering them leguminous forage, for example some farmers grow Lablab purpureus to supplement their donkeys in Botswana. Although leguminous forages are not concentrates they are good sources of protein. Donkeys can be fed dried groundnut tops or cowpea hay for protein. Urea must never be fed to donkeys because of the risk of ammonia poisoning. Some cattle feeds contain additives like monensin, which can be dangerous to equids. Therefore, cattle rations should not be fed to donkeys unless the contents are known to be free of urea and additives like monensin.

Cereals and cereal by-products such as millet, sorghum, maize and their brans can be fed to donkeys as a source of energy. By-products like brewers' spent grains are good sources of energy and proteins to donkeys. 'Chibuku' (fermented sorghum drink) spent grain can be fed to donkeys when available.

Conclusion

Donkeys are non - selective grazers and can consume a wide variety of feedstuffs. As free - ranging animals, they seldom need any additional feed. However, when the animals are expected to produce extra work or when the range has been heavily depleted, supplementary feeding may be required. A wide variety of crop residues, e.g. cereal stovers and leguminous forages and crop by-products such as maize and sorghum bran are suitable feeds for donkey supplementation. The supplementary feeding of donkeys. however, should only be for special purposes and for select groups of animals. Ideally, donkey feeding should not compete with that of other domestic animals whose supplementary feeding may be more beneficial to the farmer.

References

Aganga A A and Tsopito C M 1998 A note on the feeding behaviour of domestic donkeys: a Botswana case study. Applied Animal Behaviour Science 60: 235 - 239

Dijkman J T 1992 A note on the influence of negative gradients on the energy expenditure of donkeys walking, carrying and pulling loads. Animal Production 54: 153 - 156

Fielding D and Krause P 1998 Donkeys. The Tropical Agriculturalist. CTA. Macmillan

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Wilson R T 1990 The Donkey. In:  An Introduction to Animal Husbandry in the Tropics. W.J.A. Payne. Longman. pp 581 - 603

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Received 3 February 2000

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