Cover Image
close this book Animal traction
View the document About this manual
View the document About the author
View the document Acknowledgments
close this folder 1. Introduction
View the document What is animal traction?
View the document History of animal traction
View the document Why use animal traction?
View the document Some considerations
View the document How can animal traction be used?
View the document Before beginning: what do you need to know?
close this folder 2. Draft animal selection
View the document Popular draft animals
View the document Determining power requirements
View the document General rules concerning power requirements
View the document Method for determining size of the hitch
View the document Determining weights of animals
View the document Selection of individual draft animals
View the document Conformation
View the document Temperament
close this folder 3. Animal husbandry
View the document Sheller
View the document Nutrition
View the document Grooming
View the document Minor medical problems and first aid
close this folder 4. Training draft animals
View the document Before training begins
View the document General comments on training procedure
View the document Training cattle
View the document Program for training cattle
View the document Training horses, donkeys and mules
View the document Program for training horses, donkeys and mules
close this folder 5. Yokes and harnesses
View the document Yokes and harnesses for cattle
View the document Yokes and harnesses for horses, donkeys and mules
View the document How to harness a horse, donkey or mule
View the document Steering systems
View the document Breeching harness
close this folder 6. Hitches
View the document Safety rules
View the document Implement hitches
View the document Vehicle hitches
View the document 7. Field operations and implements
close this folder 8. Economic and technical assistance
View the document Farm planning assistance
View the document Equipment options
View the document Credit for equipment
View the document Credit for animals
View the document Procedures and controls
close this folder 9. Animal traction extension
View the document Extension education
View the document Appendix A: Animal power
close this folder Appendix B: Animal nutrition
View the document Energy needs: bovine animals
View the document Energy needs: equine animals
View the document Nutrient needs of draft animals: protein, minerals, vitamins
View the document Feeds and feed composition
View the document Calculating a ration
View the document Recommended rations and feeding practices
close this folder Appendix C: Disease recognition and control
View the document Parasites and parasitic disease
View the document Appendix D: Workshop and spare parts inventory
View the document Appendix E: Animal traction instruction forms
View the document Appendix F: Animal breeds used for power
View the document Bibliography
View the document Resources
View the document GIossary

Determining power requirements

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.

Draft

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

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.

Work Characteristics

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.)