| Animal traction |
|2. Draft animal selection|
Farmers must be able to select the animal or animals most appropriate for their needs. The animals they choose must be culturally acceptable, trainable, maintainable, and profitable within the overall farm plan. It is also important that the animal be available locally, since these animals are already adapted to local feeds and climate and are likely to be resistant to diseases in the region. Of course, farmers should choose healthy animals from strong stock. In some areas, farmers must consider social or religious traditions which restrict the ownership or use of animals.
In this chapter the word "bovine" applies to cattle (or cows) and the word "equine'' refers to horses and horse-like animals (donkeys and mules).
The most commonly-used draft animals are cattle. Among cattle oxen are often preferred, because they are well-muscled and have good temperaments. An ox is a bull which has been castrated and trained to pull loads, but the term is sometimes used to describe a working cow. In this manual, "ox" will refer to animals of either sex. Some stockmen define oxen by age as well, distinguishing them from younger "bullocks" by their full mouths (present at four years of
age.) Oxen are well-adapted to savanna and forest-savanna lands. Their use in rain forest zones has been restricted by disease, most notably trypanosomiasis, or bovine sleeping sickness.
In arid areas, the cost of maintaining cattle is often too great to make oxen a feasible source of farm power. Donkeys are better suited to these climates and often supply sufficient power for the kind of agriculture practiced. Donkeys are popular draft animals because they are inexpensive (often less than half the price of oxen on the live market), easy to train, and effective where shallow breaking rather than overturning of the soil is all that is needed before planting begins. The use of light equipment and the improvement of husbandry techniques has made it increasingly clear that donkeys are an important source of farm power.
Horses, by contrast, have not been popular draft animals in some areas of the world, notably West Africa. Horses can be more expensive to feed than bulls because they are not ruminant animals and therefore use roughage less efficiently. While they theoretically provide more power than bulls, horses do not deliver a sustained tractive, or pulling, effort under difficult conditions. However, horses are much faster than oxen.
Mules found in Africa are rarely used for draft purposes. Like horses, mules are expensive to feed. But where they are culturally acceptable (because they are a crossbreed, they are considered unclean by some Muslims), they have great potential. They have the intelligence and sure-footedness of the donkey and the strength of the horse, and are easily harnessed. A mule is a cross between a male donkey (jack) and a female horse (mare). The male offspring of this cross, called a horse mule, is always sterile, while the female offspring, or mare mule, is usually infertile. The female donkey, known as a jennet or jenny, is rarely bred with the male horse, or stallion. However, their offspring, the macho (male) and hinny (female), are basically indistinguishable from mules, and are good work animals.
Camels are used as pack animals through much of the Sahara. In Mauritania, Niger, Chad, Mali and Senegal they are used to supply power for drawing water; occasionally they are used to draw plows or light weeding implements. For information on husbandry and use of camels as draft animals, see page 234.
The domestic buffalo is used extensively as a draft animal in Asia; less commonly in Egypt and the Near East. Attempts have been made to cross Asian domestic and African wild breeds, but in each instance the resulting population succumbed to disease. Some researchers feel that futher experiments will prove the value of importing and breeding the animal in Africa, as its milk, meat, and labor potentials are high. Today experimental herds are maintained in Mozambique and Tanzania. Buffalo work at a slower rate than oxen, but are generally considered to be stronger and better adapted to wet terrain.
Except for camels, any of the animals mentioned above can be trained and harnessed using the methods described in the chapter on training.
Before attempting to determine the kind and number of animals required for any particular farm, animal owners should be familiar with the concepts of pulling (draft) capacity and power. They should also consider the work characteristics of draft animals.
In order to move any object, an animal must exert a force equal to the weight or resistance of that abject. For example, it takes 50 kilograms (kg) of force to move a 50kg log. If the movement is accomplished by pulling, rather than by lifting, or carrying, the force is called draft.
The draft capacity of an animal increases with its weight. A generally accepted rule is that an animal can exert a constant pull on a load which equals approximately one-tenth of its body weight. The rule applies when the animal is allowed to assume a natural pace and expected to produce an extended rather than a concentrated effort. A 300-kg bull, for example, can pull a 30-kg log all day, but if it is made to pull 130 kg, it will work only three or four hours before it tires. If it is made to pull at a faster pace, it also will tire sooner.
A draft animal must be able to produce bursts of extra force as well as work at a steady pace. Under normal conditions, 30 kg of force may be required to pull a log, but if it must be dragged up a hill, or if the log catches in a gully, the force needed (draft requirement) increases. Horses, mules and oxen are preferred draft animals because they can pull loads over long distances at reasonable speeds and, when necessary, provide extra pulling capacity.
Power is the combination of pulling capacity and speed, or pace. Under normal conditions, a large horse will pull a 150-pound (lb) load at a steady rate of 2-1/2 miles per hour (mph). This rate of work is defined as one horsepower (hp). A bull of the same weight, pulling the same load, will assume a normal pace of 1-1/2 mph. At the end of an eight-hour day, the horse will have moved the load further, or produced more work than the bull, and is thus said to be more powerful than the bull.
Tests have shown that light horses, bulls, buffalo, mules and camels all provide about threequarters horsepower, cows about onehalf horsepower, and donkeys onethird horsepower. But it must be remembered that these are the rates at which the animals normally deliver force, not the maximum force they can produce in a given instant. In pulling tests, horses have, for several seconds, exerted pulls up to twice their weight and bulls have
pulled up to their actual weight. But the intensity of such efforts uses up the animal's strength and reduces the total time it is able to work.
Animals vary not only in their ability to pull loads, but also in the number of hours they will work. In the tropics, breeds of oxen will pull between one-seventh and onetenth of their weight for four to five hours per day. Donkeys will pull about one-fifth of their weight for three to four hours. In tests performed in Africa, bulls worked longer when the load was decreased slightly and the work done in two sessions, two to three hours in the morning and two to three hours in late afternoon. Donkeys refused to work beyond three or four hours regardless of how the work was distributed and in spite of a reduction in the size of the load.
(Source: CEEMAT, Manuel de Culture avec Traction Animale. 1968.)
The above information, qualified by the following rules, makes it possible to determine the kind and number of draft animals needed to power various field operations:
• Given the soil conditions of a region, the weight of the implement to be used and the average depth at which the implement will work, the animal(s) must be able to deliver, for an extended period of time, a force equal to and preferably more than the total resistance, or draft requirement of the work. Tables 1 and 2 gives the draft requirements of various field implements.
• Work that requires frequent "peak efforts" (pulling a plow through rooted or rocky soil; pulling a cart over hilly terrain) tires animals quickly. The operator must compensate by reducing the length of the work day, reducing the intensity of the work (for example, taking smaller cuts with the plow), or providing frequent rests. The alternative is to increase the number of animals used.
• Individual animals do not pull to capacity when hitched in pairs or multiple arrangements. Tests have shown that the individual is 7.5 percent less efficient when it works within a pair. The percentage increases to 15, 22, 30 and 37 percent when the animal works in a team of three, four, five and six animals, respectively.
• As the line of pull is lowered (or as the angle between the line of pull and the ground becomes more acute), less power is needed to move the load. Donkeys and short-legged cattle can produce more power than their weight would indicate because they are closer to the ground.
• Animals deliver maximum performance only when the harness (yoke, collar or breastband) is properly fitted and provides a broad, smooth surface against which to push. Test evidence suggests that bovine animals can deliver 2550 percent more horsepower when harnessed in a breastband or collar rather than a yoke. The difference is explained in the lower point of draft, the increased comfort of the harness, and in the fact that the animal pushes against a much larger surface area.
• Animals must be in good health and properly trained.
A basic approach to determining the kind and number of animals required is to estimate the maximum power the farmer will need and then calculate the size of the animal or team of animals that could supply it. The combination of animals that will satisfy the farmer's power needs is called a hitch. The size of the hitch can be determined by using the tables below, or by making the calculations found in Appendix A.
Table 2 gives the draft requirements of various field operations. Remember that the draft requirement is the amount of power needed to pull an implement through the soil.
Tables 3 and 4 give the amount of power donkeys and bulls, respectively, can deliver in relation to their body weight and number of individuals in the hitch.
To determine the kind of hitch needed, first find the draft requirement of the most difficult operation to be performed (Tables 1 and 2). Use Tables 3 and 4 to find which size animal or combination of animals will deliver this amount of power. Then determine the weights of the available animals to match animal power to draft requirements.
Difficulty of work-The most difficult field operation will be plowing fairly light soils during the rainy season with a single moldboard plow. The farmer's fields are old (have been cultivated the previous season) and plowing depth will not exceed 15 centimeters (cm).
Draft requirements-According to Table 1 about 70 kg of pulling power are needed to do this kind of work.
Hitch options-Tables 3 and 4 can be used to determine two hitches that would satisfy the draft requirement:
1) two 300-kg bulls (69.5 kg of power or draft)
2) four 110-kg donkeys (69 kg of power or draft).
*See Chapter 7 for a description of these operations and implements.
Choice of hitch-The decision is made based on these criteria: availability of animals, cost of animals, daily work potential of animals, cost of harness, and availability and cost of feed.
If they are available and the farmer can afford them, bulls are generally the best choice because they will work longer hours per day and they require less harness equipment. Bulls weighing less than 300 kg each could be used if they were harnessed in breastbands or collars rather than in a yoke. Animals can deliver more of their potential power when working in these types of harnesses.
If animals to be used are of the same size, match draft requirement to figure in TOTAL columns. For example, an animal owner could meet a requirement of 56 kg of power by using two 150-kg donkeys, three 110-kg donkeys, or four small animals of 90 kg apiece.
If animals are of different sizes, use single animal column for any size hitch, and add individual power together to get hitch total.
To determine an animal's weight, first measure the length of the animal from point of shoulder to point of rump (A-B) and the circumference of its torso at point of heart (C) with a tape or rope. (See the drawing on page 20.) When taking the torso or girth measurement, observe these rules:
• Measure in the morning before the animal drinks. Don't give it hay the night before.
• Have the animal stand squarely with its head in a normal position.
• Pull the tape snugly around the torso, at the smallest circumference behind the shoulders.
Next, follow these formulas:
For bovine animals
Substitute measurements A-B (length) and C (circumference of torso at point of heart, or girth) into this formula:
(girth x girth x length)/300 = weight
For this formula, measurements must be taken in inches. If a metric tape or rope/rule is used to measure the animal, centimeters must be converted to inches before the formula can be used. One inch = 2.54 cm.
Girth of bull measures 152 cm, length measures 135 cm.
152/2.54 = 60 inches (girth)
135/2.54 = 53 inches (length)
(60 x 60 x 53)/300 = 636 lbs
Since one kg = 2.2 lbs, the weight of the animal in kg is obtained by dividing 2.2 into the answer above (636 lbs).
636/2.2 = 289 kg
The bull weighs 636 lbs or 289 kg.
An alternate method for estimating the weight of a steer (castrated bull):
Live weight • 1.04 [27.5758 x heart girth) -1.04967]
Substitute measurements A-B (length) and C (girth) into this formula:
(girth x girth x length)/300 + 50 lbs = weight
Measurements must be taken in inches, or converted into inches, before the formula is used.
Donkey's girth measures 37 inches, donkey's length measures 35 inches.
(37 x 37 x 35)/300 + 50 = weight of donkey
160 + 50 = 210 lbs
If the animal's weight is to be expressed in kg,
210/2.2 = 95 kg
The donkey weighs 210 lbs or 95 kg.
Once farmers decide what kind of draft animal will be used, they must be able to choose individual animals which are sound and trainable and have a considerable work expectancy and resale value. Selecting a good draft animal is a matter of evaluating both physical and behavioral attributes. Age, sex, conformation (shape), and temperament are helpful criteria for judging a draft animal's value. The farmer's total animal needs must be noted when judging an individual animal. If it is to be used as a pair, it should be roughly the same age and size as its work mate, and should be the same sex.
Age of Bovine Animals
Ideally, farmers should raise their own draft cattle or purchase them when they are very young. This allows the farmers to provide proper nutrition during the critical growth stage as well as to observe and shape the animal's behavior long before it is put to work.
Oxen are normally put to work between the ages of three and four years. They may be trained at two to three years of age and given light work for a season. However, before the age of three, oxen have little power, and hard work can stunt their growth or cause abnormal development of bone and muscle. After the age of four, animals may be difficult to handle and train; they must be broken of old habits before their power can be used.
Although oxen can work until they are 12 or older, many farmers prefer to sell them as soon as their work capacity tapers off. A common practice is to work oxen hard until age seven or eight, use them as a reserve or alternate animal (or pair) for a season or two, and then sell them for butchering.
When buying an ox, the purchaser can determine the animal's age by counting its teeth. Because the approach of an unfamiliar person may cause the animal to shy or to struggle, it is best to have the owner open the animal's mouth. Otherwise restrain the animal and pry open the mouth by pulling up on the nostrils and down on the lower jaw.
Cattle have front teeth only in the lower jaw. Temporary teeth appear at one month. The first permanent teeth appear at age two. By age five, the animal has a full set of permanent teeth. The age of older animals can be determined by observing the wear patterns of the teeth and matching them to the patterns shown in the illustration on the next page. An alternate method is to count the number of rings on the animal's horns; each ring corresponds to one year of growth, the first ring appearing at age two.
Age of Equine Animals Recommended ages for training and working equine animals are very similar to those outlined for cattle. However, in practice, these animals are worked until they are older because their meat is less valuable. The age of a horse, donkey or mule can be determined by comparing the animal's mouth to the diagrams on the following page. As the animal grows older, the enamed wears off the tooth, giving it a smooth, white grinding surface (the dark center disappears). The teeth grow longer and begin to slant; the entire mouth elongates. Compare the side views of the four-and thirtyyear-old horse and note the increased pointing of the jaw. The correct method for opening the animal's mouth is as follows:
• Place the palm of one hand under the animal's jaw;
• Insert the thumb and middle finger into the animal's mouth on either side of the lower jaw, at a point behind the teeth;
• Rub or press the gums with these fingers; this will cause the animal to open its mouth; • Grasp the tongue with the other hand, pull the tongue out, and hold it to one side so that teeth can be seen.
Sex of Bovine Animals
Sex has a bearing on the power and temperament of draft animals. As a rule males tend to be bigger, more powerful, and more difficult to train than females. Females have less endurance and, of course, cannot be used when they are carrying or nursing young. Studies of African cattle have shown that within the same breed and age bracket, males tend to be 50-100 kg heaver than females and can work twice as long during a given day
(bulls, five to six hours; cows, two to three hours). Studies from temperate zones show more pronounced differences in size and power.
Such evidence makes it clear that there is an advantage to using male animals. However, the males of some breeds of cattle and buffalo have proven particularly difficult to train. In these circumstances, the animals are castrated at the age of one and a half years in order to make them more docile. There is disagreement about the value of castration, however. Some farmers feel that this makes the animals lazy or interferes with their physical development. Tests have substantiated that castrating eight-month-old calves retards their growth. Other tests, comparing two-year-old cas-bated and entire male buffaloes, showed that the animals performed equally well. Castration also limits a small farmer's ability to raise his own stock, especially if he owns only a few animals.
Sex of Equine Animals
Castrated horses or donkeys (geldings) are preferred over stallions because they are eventempered and manageable in the presence of females. Female horses, mules and donkeys are nearly as powerful as males and geldings, but are known for their stubbornness and unpredictable moods.
Conformation refers to the form or shape of an animal. An animal with good conformation has a shape which shows the normal characteristics of its species and breed.
An animal used for draft must have a build well suited for pulling. It should be low to the ground, have powerful shoulders and legs, and have a broad frontal dimension that will accommodate the placement of a harness. It must be big enough to deliver, alone or in a pair, the power needed to pull equipment for an extended period of time. It must also be able to exert the concentrated or "instantaneous" effort needed to overcome temporary increases in the draft requirement caused by roots, rocks, hard soil, or inclines.
While some animals are bred to produce good draft abilities, within any breed individual animals vary greatly in these qualities, and care must be taken to choose those with the most potential. A thin but well-balanced animal can be strengthened with a good diet, health care, and work. However, an animal with a swayback, bad legs or impaired vision will be a constant source of trouble.
Selection is a process of matching ideal qualities against those seen or latent in a given animal. Good draft animals, regardless of species or breed, will have the following qualities:
• head well proportioned; squarish, sculptured look
• balanced vision and hearing; head carriage high and straight
• normal mouth; good teeth and jaw structure
• body should have depth and width; short, full neck, full shoulders, broad chest, and straight, broad beck
• wide, thick hindquarters, lowset and evenly-fleshed
• short legs, straight and square to the body; ample bone
• clean, well-developed joints; no swelling or unusual boniness; no turning in or out of knees or hoofs; free movement of limbs
• feet straight, hard; normal angulation of hoof.
The illustrations-below can serve as general guidelines for identifying qualities in don keys and mules as well as horses.
The proper and faulty conformation of the forelegs when viewed from the side:
B-forelegs too far under body
C-forelegs too far advanced
E-calf-kneed-standing with knees too far back.
The proper and faulty conformation of the hind legs when viewed from the side:
B-sickle-hocked-hind legs too far under body
C-legs set too far back
D-hock joint too straight.
The proper and faulty conformation of the forelegs (top) when viewed from the front, and the hind legs (bottom) when viewed from the rear. The forelegs:
B-splay-footed or basenarrow forefeet, toe cut out, heels in
D-knock-kneed, set close together with toes pointing outward
E-conformation predisposing to interfering
F-knees set close together
G-pigeon-toed or toe narrow-a conformation which will cause the animal to wing or throw out the feet as they are elevated.
The hind legs:
B-hind legs set too far apart
C-bandy-legged-wide at the hocks and hind feet toe-in
D-hind legs set too close together i E-cow-hocked.
Temperament refers to the nature or disposition of an animal. Part of its temperament is determined genetically, both by breed and parentage; some of it is learned-a response to the treatment it receives from other animals or the people who raise and handle it.
Temperament is reflected in an animal's behavior, the way it moves and acts, and the way it reacts to the things around it. It is difficult to know much about temperament from the quick evaluation that usually precedes the purchase of a draft animal. The buyer must guess, from what is observable, whether or not an animal will accept new routines or maintenance and training, behave well in a pair, and prove to be a spirited yet steady-paced and manageable worker. Sometimes, what is observable is not typical of the animal's behavior. A basically lethargic bull, for example, may become very alert or nervous at the approach of a stranger, exhibiting a fierceness that could be misinterpreted as a strong yet controllable spirit. A donkey that is mishandled and mismanaged might kick or butt at its owner, or at any adult, but be led away quite easily by a child. The buyer must be aware of such possibilities and at the same time drew some basic conclusions about the animal's temperament.
The following are signs of good temperament:
• Good overall conformation and health. The animal has no physical handicaps that require it to compensate with aggressive or stubborn behavior. An animal with bad vision or hearing, an unsound leg or joint, or with a chronic respiratory or muscular weakness, protects itself by balking, spooking, shying, refusing to be harnessed or lying down during work. Its temperament is affected or shaped by its physical condition.
• The animal accepts the handling of the owner. The owner can pick up the animal's foot, open its mouth, lead it with a rope without having to use force or harsh measures.
• It does not shy or kick at other animals. The buyer should try to be present when it is being turned out with a herd or put into a corral with other animals. If an animal is unusually aggressive or cowardly, it may not work well in a pair. Aggressive animals force their work-mates to shy or lean out of the yoke or harness, while cowardly animals may refuse to step evenly with their mates, lagging behind.
When an animal is taken from its herd or original owner and staked out or corralled in a new place, it may experience shock. The animal may show signs of aggression, withdrawal, stubbornness, fear, or general anxiety. None of these reactions is unnatural during the adjustment period, and should not be taken as a sign of an unsuitable disposition. An animal's character becomes clear later, during training and preseason work. At that time the farmer can judge the ability of the animal to work as part of a pair or team. Buying an animal early in the offseason allows the owner time to seek a replacement should a problem arise.