Material on hair-cutting and shearing was written with the assistance of J.F. Copplestone’s article on the subject in the 3rd edition of this Encyclopaedia.
Several animals convert high-fibre feeds, called roughage (over 18% fibre), into edible food that is consumed by humans. This ability comes from their four-stomach digestion system, which includes their largest stomach, the rumen (for which they gain the designation ruminants) (Gillespie 1997). Table 1 shows the various types of ruminant livestock that have been domesticated and their uses.
Table 1. Types of ruminants domesticated as livestock
|
Ruminant type |
Uses |
|
Cattle |
Meat, milk, draught |
|
Sheep |
Meat, wool |
|
Goats |
Meat, milk, mohair |
|
Camelids (llama, alpaca, dromedary and bactrian camels) |
Meat, milk, hair, draught |
|
Buffalo (water buffalo) |
Meat, draught |
|
Bison |
Meat |
|
Yaks |
Meat, milk, wool |
|
Reindeer |
Meat, milk, draught |
Production Processes
Processes for rearing ruminants vary from intensive, high-production operations such as raising beef cattle on large, 2,000-km2 ranches in Texas to communal grazing such as the nomadic herders of Kenya and the United Republic of Tanzania. Some farmers use their cattle as oxen for traction power in farm tasks such as ploughing. In humid areas, water buffalo serve the same purpose (Ker 1995). The trend is toward high-production, intensive systems (Gillespie 1997).
High-volume, intensive beef production depends on various interdependent operations. One is the cow-calf system, which involves keeping a herd of cows. The cows are bred by bulls or artificial insemination annually to produce calves, and, after weaning, the calves are sold to cattle feeders to raise for slaughter. Male calves are castrated for the slaughter market; a castrated calf is called a steer. Pure-bred breeders maintain the herds of breeding stock, including bulls, which are very dangerous animals.
Sheep are produced in either range or farm flocks. In range production, flocks of 1,000 to 1,500 ewes are common. In farm flocks, production is usually small and typically a secondary enterprise. Sheep are raised for their wool or as feeder lambs for the slaughter market. Lambs are docked, and most male lambs are castrated. Some enterprises specialize in raising rams for pure-bred breeding.
Goats are raised through either range or small-farm production for their mohair, milk and meat. Pure-bred breeders are small operations that raise rams for breeding does. Specific breeds exist for each of these products. The goats are dehorned, and most males are castrated. Goats browse on shoots, twigs and leaves of brush plants, and thus they may also be used to control brush on a ranch or farm.
Other major processes involved in rearing cattle, sheep and goats include feeding, disease and parasite control, hair clipping and fleece shearing. The milking process and livestock waste disposal are addressed in other articles in this chapter.
Cattle, sheep and goats are fed in several ways, including grazing or feeding hay and silage. Grazing is the least expensive way to deliver forage to animals. Animals typically graze on pastures, wild lands or crop residues, such as corn stalks, which remain in the field after crop harvests. Hay is harvested from the field and typically stored loose or in stacked bales. The feeding operation includes moving the hay from the stack to the open field or into mangers to feed the animals. Some crops such as corn are harvested and converted into silage. Silage is typically moved mechanically into mangers for feeding.
The control of diseases and parasites in cattle, sheep and goats is an integral part of the livestock-rearing process and requires animal contact. Routine visits to the herd by a veterinarian are an important part of this process, as is observing vital signs. Timely vaccination against diseases and quarantining diseased animals are also important.
External parasites include flies, lice, mange, mites and ticks. Chemicals are one control against these parasites. Pesticides are applied by spraying or through insecticide-impregnated ear tags. The heel fly lays eggs on the hair of cattle, and its larva, the cattle grub, burrows into the skin. A control for this grub is systemic pesticides (spread throughout the body through spray, dips or as a feed additive). Internal parasites, including roundworms or flatworms, are controlled with drugs, antibiotics or drenches (oral administration of a liquid medication). Sanitation is also a strategy for the control of infectious diseases and parasite infestations (Gillespie 1997).
The removal of hair from live animals helps to maintain their cleanliness or comfort and to prepare them for exhibitions. Hair may be sheared from live animals as a product, such as the fleece from sheep or mohair from goats. The sheep shearer catches the animal in a pen and drags it to a stand where it is laid on its back for the shearing operation. It is pinned by the shearer’s legs. Hair cutters and sheep shearers use a hand-operated scissors or motorized shears to clip the hair. The motorized shears are typically powered by electricity. Prior to shearing and also as part of gestation management, sheep are tagged and crutched (i.e., hair encrusted with faeces is removed). The cut fleece is manually trimmed according to the quality and staple of the hair. It is then compressed into packs for transportation using a hand-operated screw or hydraulic ram.
Facilities used for raising cattle, sheep and goats are generally considered to be either confined or unconfined. Confined facilities include confinement houses, feedlots, barns, corrals (holding, sorting and crowding pens), fences and working and loading chutes. Unconfined facilities refer to pasture or range operations. Feeding facilities include storage facilities (vertical and horizontal silos), feed grinding and mixing equipment, haystacks, conveying equipment (including augers and elevators), feed bunks, water fountains and mineral and salt feeders. In addition, sun protection may be provided by sheds, trees or overhead lattice work. Other facilities include back rubbers for parasite control, creep-feeders (allows feeder calves or lambs to feed without adults feeding), self-feeders, calf shelters, cattle-guard gates and cattle treatment stalls. Fencing may be used around pastures, and these include barbed wire and electric fences. Woven wire may be required to contain goats. Free-ranging animals would require herding to control their movement; goats may be tethered, but require shade. Dipping tanks are used for parasite control in large sheep flocks (Gillespie 1997).
Hazards
Table 2 shows several other processes of cattle, sheep and goat handling, with associated hazardous exposures. In a survey of farm workers in the United States (Meyers 1997), handling livestock represented 26% of lost-time injuries. This percentage was higher than any other farm activity, as shown in figure 1. These figures would be expected to be representative of the injury rate in other industrialized countries. In countries where draught animals are common, injury rates would be expected to be higher. Injuries from cattle usually occur in farm buildings or in the vicinity of buildings. Cattle inflict injuries when they kick or step on people or crush them against a hard surface such as the side of a pen. People may also be injured by falling when working with cattle, sheep and goats. Bulls inflict the most serious injuries. Most of the people injured are family members rather than hired workers. Fatigue can reduce judgement, and thus increase the chance of injury (Fretz 1989).
Table 2. Livestock rearing processes and potential hazards
|
Process |
Potential hazardous exposures |
|
Breeding, artificial inseminating |
Violent acts by bulls, rams or bucks; slips and falls; |
|
Feeding |
Organic dust; silo gas; machines; lifting; electricity |
|
Calving, lambing, kidding |
Lifting and pulling; animal behaviour |
|
Castrating, docking |
Animal behaviour; lifting; cuts from knives |
|
Dehorning |
Animal behaviour; cuts from trimmers; caustic |
|
Branding and marking |
Burns; animal behaviour |
|
Vaccinating |
Animal behaviour; needle sticks |
|
Spraying and dusting/drenching, worming |
Organophosphates |
|
Foot/hoof trimming |
Animal behaviour; awkward postures; tool-related |
|
Shearing, tagging and crutching, washing and clipping |
Awkward postures and lifting; animal behaviour; |
|
Loading and unloading |
Animal behaviour |
|
Manure handling |
Manure gases; slips and falls; lifting; machines |
Sources: Deere & Co. 1994; Fretz 1989; Gillespie 1997; NIOSH 1994.
Figure 1. Estimates of lost-time injury frequency by farm activity in the United States, 1993
Livestock exhibit behaviours that can lead to injuries of workers. The herding instinct is strong among animals such as cattle or sheep, and imposed limits such as isolation or overcrowding can lead to unusual behavioural patterns. Reflexive response is a common defensive behaviour among animals, and it can be predicted. Territorialism is another behaviour that is predictable. A reflexive escape struggle is apparent when an animal is removed from its normal quarters and placed in a confined environment. Animals that are restrained by chutes for loading for transportation will exhibit agitated reflex response behaviour.
Dangerous environments are numerous in cattle, sheep and goat production facilities. These include slippery floors, manure pits, corrals, dusty feed areas, silos, mechanized feeding equipment and animal confinement buildings. Confinement buildings may have manure storage pits, which can emit lethal gases (Gillespie 1997).
Heat exhaustion and stroke are potential hazards. Heavy physical labour, stress and strain, heat, high humidity and dehydration from lack of drinking water all contribute to these hazards.
Livestock handlers are at risk for developing respiratory illness from exposure to inhaled dusts. A common illness is organic dust toxic syndrome. This syndrome may follow exposures to heavy concentrations of organic dusts contaminated with micro-organisms. About 30 to 40% of workers who are exposed to organic dusts will develop this syndrome, which includes the conditions shown in table 3; this table also shows other respiratory conditions (NIOSH 1994).
Table 3. Respiratory illnesses from exposures on livestock farms
|
Organic dust toxic syndrome conditions |
|
Precipitin-negative farmer’s lung disease |
|
Pulmonary mycotoxicosis |
|
Silo unloader’s syndrome |
|
Grain fever in grain elevator workers |
|
Other important respiratory illnesses |
|
“Silo fillers’ disease” (acute toxic inflammation of the lung) |
|
“Farmer’s lung disease” (hypersensitivity pneumonitis) |
|
Bronchitis |
|
Asphyxiation (suffocation) |
|
Toxic gas inhalation (for example, manure pits) |
Hair cutters and sheep shearers face several hazards. Cuts and abrasions may result during the shearing operation. Animal hoofs and horns also present potential hazards. Slips and falls are an ever-present hazard while handling the animals. Power for the shears is sometimes transferred by belts, and guards must be maintained. Electrical hazards are also present. Shearers also face postural hazards, particularly to the back, as a result of catching and tipping the sheep. Constraining the animal between the shearer’s legs tends to strain the back, and torsional movements are common while shearing. Manual shearing usually results in tenosynovitis.
The control of insects on cattle, sheep and goats with pesticide spray or powder can expose workers to the pesticide. Sheep dips submerge the animal in a pesticide bath, and handling the animal or contact with the bath solution or contaminated wool can also expose workers to the pesticide (Gillespie 1997).
Common zoonoses include rabies, brucellosis, bovine tuberculosis, trichinosis, salmonella, leptospirosis, ringworm, tapeworm, orf virus disease, Q fever and spotted fever. Diseases that may be contracted while working with hair and fleece include tetanus, salmonellosis from tagging and crutching, leptospirosis, anthrax and parasitic diseases.
Animal faeces and urine also provide a mechanism for infection of workers. Cattle are a reservoir for cryptosporidosis, a disease that can be transmitted from cattle to humans through the faecal-oral route. Calves with diarrhoea (scours) may harbour this disease. Schistosomiasis, an infection by blood flukes, is found in cattle, water buffalo and other animals in several parts of the world; its life cycle goes from eggs excreted in urine and faeces, developing into larvae, which enter snails, then to free-swimming cercariae that attach to and penetrate human skin. Penetration can occur while workers are wading in water.
Some zoonoses are arthropod-borne viral diseases. The primary vectors for these diseases are mosquitoes, ticks and sandflies. These diseases include arboviral encephalitides transmitted by ticks and milk from sheep, babesiosis transmitted by ticks from cattle and Crimean-Congo haemorrhagic fever (Central Asian haemorrhagic fever) transmitted by mosquitoes and ticks from cattle, sheep and goats (as amplifying hosts) during epizootics (Benenson 1990; Mullan and Murthy 1991).
Preventive Action
The principal occupational hazards that occur in rearing ruminants include injuries, respiratory problems and zoonotic diseases. (See “A checklist for livestock rearing safety practices”.)
Stair steps should be maintained in good condition, and floors must be even to reduce fall hazards. Guards on belts, mechanical screws, compression rams and shear sharpening equipment should be maintained. Wiring should be maintained in good condition to prevent electrical shock. Ventilation should be assured wherever internal combustion engines are used in barns.
Training and experience in properly handling animals helps to prevent injuries related to the animals’ behaviour. Safe livestock handling requires understanding of both innate and acquired components of animal behaviour. Facilities should be designed so workers do not have to enter small or enclosed areas with animals. Lighting should be diffuse, since animals may become confused and balk around bright lights. Sudden noises or movements may startle cattle, causing them to crowd a person against hard surfaces. Even clothing hanging on fences flapping in the wind can startle cattle. They should be approached from the front so as not to surprise them. Avoid use of contrasting patterns in cattle facilities, because cattle will slow or stop when they see these patterns. Shadows across the floor should be avoided because cattle may refuse to cross over them (Gillespie 1997).
Risks of organic dust exposure can be minimized in several ways. Workers should be aware of the health effects of breathing organic dust and inform their physician about recent dust exposures when seeking help for respiratory illness. Minimizing spoilage of feed can minimize potential fungal spore exposures. To avoid such hazards, workers should use mechanized equipment to move decaying materials. Farm operators should use local exhaust ventilation and wet methods of dust suppression to minimize exposure. Appropriate respirators should be worn when organic dust exposure cannot be avoided (NIOSH 1994).
Preventing zoonoses depends upon maintaining clean livestock facilities, vaccinating the animals, quarantine of sick animals and avoiding exposure to sick animals. Rubber gloves should be worn when treating sick animals to avoid exposures through any cuts in the hands. Workers who become sick after contact with a sick animal should seek medical help (Gillespie 1997).