Monday, 28 March 2011 19:46

Fish Farming and Aquaculture

Rate this item
(1 Vote)

Background

Rearing marine organisms for food has been a widespread practice since ancient times. However, large-scale farming of molluscs, crustaceans and bony fishes has rapidly gained momentum since the early 1980s, with 20% of the world’s seafood harvest now farmed; this is projected to increase to 25% by 2000 (Douglas 1995; Crowley 1995). Expansion of world markets contemporaneous with depletion of wild stocks has resulted in very rapid growth of this industry.

Land-based aquaculture takes place in tanks and ponds, while water-based culture systems generally employ screened cages or moored net pens of widely varying designs (Kuo and Beveridge 1990) in salt water (mariculture) or fresh rivers.

Aquaculture is performed as either an extensive or intensive practice. Extensive aquaculture entails some form of environmental enhancement for naturally produced species of fish, shellfish or aquatic plants. An example of such a practice would be laying down oyster shells to be used as attachment substrate for juvenile oysters. Intensive aquaculture incorporates more complex technology and capital investment in the culture of aquatic organisms. A salmon hatchery that uses concrete tanks supplied with water via some delivery system is an example. Intensive aquaculture also requires greater allocation of labour in the operation.

The process of intensive aquaculture includes the acquisition of broodstock adults used for production of gametes, gamete collection and fertilization, incubation of eggs and juvenile rearing; it may include rearing of adults to market size or release of the organism into the environment. Herein lies the difference between farming and enhancement aquaculture. Farming means rearing the organism to market size, generally in an enclosed system. Aquaculture for enhancement requires the release of the organism into the natural environment to be harvested at a later date. The essential role of enhancement is to produce a specific organism as a supplement to natural production, not as a replacement. Aquaculture can also be in the form of mitigation for loss of natural production caused by a natural or human-made event—for example, construction of a salmon hatchery to replace lost natural production caused by the damming of a stream for hydroelectric power production.

Aquaculture can occur in land-based facilities, on-bottom marine and freshwater environments and floating structures. Floating net pens are used for fish farming, and cages suspended from raft or buoy flotation are commonly used for shellfish culture.

Land-based operations require the construction of dams and/or excavation of holes for ponds and raceways for water flushing. Mariculture can involve the construction and maintenance of complex structures in harsh environments. Handling of smolt (for bony fishes) or tiny invertebrates, feed, chemical treatments for water and the animals being raised and wastes have all evolved into highly specialized activities as the industry has developed.

Hazards and Controls

Injuries

Fish farming operations afford many injury risks, combining some of those common to all modern agriculture operations (e.g., entanglement in large machinery, hearing loss from prolonged exposure to loud engines) with some hazards unique to these operations. Slips and falls can have particularly bad outcomes if they occur near raceways or pens, as there are the dual added risks of drowning and biological or chemical contamination from polluted water.

Severe lacerations and even amputations may take place during roe-stripping, fish butchering and mollusc shelling and can be prevented by the use of guards, protective gloves and equipment designed specifically for each task. Lacerations contaminated by fish slime and blood can cause serious local and even systemic infections (“fish poisoning”). Prompt disinfection and debridement is essential for these injuries.

Electrofishing (used to stun fish during survey counts, and increasingly in collection of broodstock at hatcheries) carries a high potential for electrical shock to the operators and bystanders (National Safety Council 1985) and should be done only by trained operators, with personnel trained in cardiopulmonary resuscitation (CPR) on site. Only equipment specifically designed for electrofishing operations in water should be employed and scrupulous attention must be paid to establishing and maintaining good insulation and grounding.

All water poses drowning risks, while cold waters pose the additional hazard of hypothermia. Accidental immersions due to falls overboard must be guarded against, as must potential for ensnarement or entrapment in nets. Approved personal flotation devices should be worn by all workers at all times on or near the water, and some thermal protection should also be worn when working around cold waters (Lincoln and Klatt 1994). Mariculture personnel should be trained in marine survival and rescue techniques, as well as CPR.

Repetitive strain injuries may also occur in butchering and hand-feeding operations and can be largely avoided by attention to ergonomics (via task analysis and equipment modifications as necessary) and frequent task rotations of manual workers. Those workers developing repetitive strain injury symptoms should receive prompt evaluation and treatment and possible reassignment.

Sleep deprivation can be a risk factor for injuries in aquaculture facilities requiring intensive labour over a short duration of time (e.g., egg harvest at salmon hatcheries).

Health hazards

Diving is frequently required in construction and maintenance of fishpens. Predictably, decompression illness (“bends”) has been observed among divers not carefully observing depth/time limits (“dive tables”). There have also been reports of decompression illness occurring in divers observing these limits but making many repetitive short dives; alternative methods (not using divers) should be developed for clearing dead fish from and maintaining pens (Douglas and Milne 1991). When diving is deemed necessary, observing published dive tables, avoiding repetitive dives, always diving with a second diver (“buddy diving”) and rapid evaluation of decompression-like illnesses for possible hyperbaric oxygen therapy should be regular practices.

Severe organophosphate poisoning has occurred in workers incidental to pesticidal treatment of sea lice on salmon (Douglas 1995). Algicides deployed to control blooms may be toxic to workers, and toxic marine and freshwater algae themselves may afford worker hazards (Baxter 1991). Bath treatments for fungal infections in fish may use formaldehyde and other toxic agents (Douglas 1995). Workers must receive adequate instruction and allotment of time for safe handling of all agricultural chemicals and hygienic practices around contaminated waters.

Respiratory illnesses ranging from rhinitis to severe bronchospasm (asthma-like symptoms) have occurred due to sensitization to putative endotoxins of gram-negative bacteria contaminating farmed trout during gutting operations (Sherson, Hansen and Sigsgaard 1989), and respiratory sensitization may occur to antibiotics in medicated fish feeds. Careful attention to personal cleanliness, keeping seafood clean during butchering and handling and respiratory protection will help ensure against these problems. Workers developing sensitivity should avoid subsequent exposures to the implicated antigens. Constant immersion of hands can facilitate dermal sensitization to agricultural chemicals and foreign (fish) proteins. Hygienic practice and use of task-appropriate gloves (such as cuffed, insulated, waterproof neoprene during cold butchering operations) will reduce this risk.

Sunburn and keratotic (chronic) skin injury may result from exposure to sunlight. Wearing hats, adequate clothing and sunscreen should be de rigueur for all outdoor agricultural workers.

Large quantities of stored fish feeds are often raided by or infested with rats and other rodents, posing a risk for leptospirosis (Weil’s disease). Workers handling fish feeds must be vigilant about feed storage and rodent control and protect abraded skin and mucous membranes from contact with potentially contaminated feeds and soiled pond waters. Feeds with known contamination with rat urine should be handled as potentially infectious, and discarded promptly (Ferguson and Path 1993; Benenson 1995; Robertson et al. 1981).

Eczema and dermatitis can easily evolve from inflammation of skin macerated by constant water contact. Also, this inflammation and wet conditions can foster reproduction of human papillaviridae, leading to rapid spread of skin warts (Verruca vulgaris). Prevention is best accomplished by keeping hands as dry as possible and using appropriate gloves. Emollients are of some value in the management of minor skin irritation from water contact, but topical treatment with corticosteroids or antibiotic creams (after evaluation by a physician) may be necessary if initial treatment is unsuccessful.

Environmental Impacts

Demand for fresh water can be extremely high in all of these systems, with estimates centring on 40,000 litres required for each 0.5 kg of bony fish raised to maturity (Crowley 1995). Recirculation with filtration can greatly reduce demand, but requires intensive application of new technologies (e.g., zeolites to attract ammonia).

Fish farm discharges can include as much faecal waste as that from small cities, and regulations are rapidly proliferating for control of these discharges (Crowley 1995).

Consumption of plankton and krill, and side effects of mariculture such as algal blooms, can lead to major disruptions in species balance in the local ecosystems surrounding fish farms.

 

Back

Read 6546 times Last modified on Tuesday, 28 June 2011 11:12

" DISCLAIMER: The ILO does not take responsibility for content presented on this web portal that is presented in any language other than English, which is the language used for the initial production and peer-review of original content. Certain statistics have not been updated since the production of the 4th edition of the Encyclopaedia (1998)."

Contents

Livestock Rearing References

Aldhous, P. 1996. Scrapie theory fed BSE complacency, now fears grow for unborn babies. New Scientist 150:4-5.

Ahlgren, GH. 1956. Forage Crops. New York: McGraw-Hill Book Co.

American Conference of Governmental Industrial Hygienists (ACGIH). 1994. Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices. Cincinnati, OH: ACGIH.

Auty, JH. 1983. Draught animal power in Australia. Asian Livestock VIII:83-84.

Banwart, WC and JM Brenner. 1975. Identification of sulfur gases evolved from animal manures. J Environ Qual 4:363-366.

Baxter, PJ. 1991. Toxic marine and freshwater algae: An occupational hazard? Br J Ind Med 48(8):505-506.

Bell, RG, DB Wilson, and EJ Dew. 1976. Feedlot manure top dressing for irrigated pasture: Good agricultural practice or a health hazard? B Environ Contam Tox 16:536-540.

Benenson, AS. 1990. Control of Communicable Diseases in Man. Washington, DC: American Public Health Association.

—. 1995. Control of Communicable Diseases Manual. Washington, DC: American Public Health Association.

Brown, LR. 1995. Meat production takes a leap. In Vital Signs 1995: The Trends that are Shaping our Future, edited by LR Brown, N Lenssen, and H Kane. New York: WW Norton & Company.

Bursey, RG. 1992. New uses of dairy products. In New Crops, New Uses, New Markets: Industrial and Commercial Products from U.S. Agriculture: 1992 Yearbook of Agriculture. Washington, DC: USDA.

Calandruccio, RA and JH Powers. 1949. Farm accidents: A clinical and statistical study covering twenty years. Am Surg (November):652-660.

Cameron, D and C Bishop. 1992. Farm accidents in adults. Br Med J 305:25-26.

Caras, RA. 1996. A Perfect Harmony: The Intertwining Lives of Animals and Humans throughout History. New York: Simon & Schuster.

Carstensen, O, J Lauritsen, and K Rasmussen. 1995. The West-Justland study on prevention of farm accidens, Phase 1: A study of work specific factors in 257 hospital-treated agricultural injuries. Journal of Agricultural Safety and Health 1:231-239.

Chatterjee, A, D Chattopadhyay, D Bhattacharya, Ak Dutta, and DN Sen Gupta. 1980. Some epidemiologic aspects of zoophilic dermatophytosis. International Journal of Zoonoses 7(1):19-33.

Cherry, JP, SH Fearirheller, TA Foglis, GJ Piazza, G Maerker, JH Woychik, and M Komanowski. 1992. Innovative uses of animal byproducts. In New Crops, New Uses, New Markets: Industrial and Commercial Products from U.S. Agriculture: 1992 Yearbook of Agriculture. Washington, DC: USDA.

Crowley, M. 1995. Aquaculture trends and technology. National Fisherman 76:18-19.

Deere & Co. 1994. Farm and Ranch Safety Management. Moline, IL: Deere & Co.

DeFoliart, GR. 1992. Insects as human foods. Crop Protection 11:395-399.

Donham, KJ. 1985. Zoonotic diseases of occupational significance in agriculture: A review. International Journal of Zoonoses 12:163-191.

—. 1986. Hazardous agents in agricultural dusts and methods of evaluation. Am J Ind Med 10:205-220.

Donham, KJ and LW Knapp. 1982. Acute toxic exposure to gases from liquid manure. J Occup Med 24:142-145

Donham, KJ and SJ Reynolds. 1995. Respiratory dysfunction in swine production workers: Dose-response relationship of environmental exposures and pulmonary function. Am J Ind Med 27:405-418.

Donham, KJ and L Scallon. 1985. Characterization of dusts collected from swine confinement buildings. Am Ind Hyg Assoc J 46:658-661.

Donham, KJ and KM Thu. 1995. Agriculture medicine and enivronmental health: The missing component of the sustainable agricultural movement. In Agricultural health and safety: Workplace, Environment, Sustainability, edited by HH McDuffie, JA Dosman, KM Semchuk, SA Olenchock, and A Senthilselvan. Boca Raton, FL: CRC Press.

Donham, KJ, MJ Rubino, TD Thedell and J Kammenmeyer. 1977. Potential health hazards of workers in swine confinement buildings. J Occup Med 19:383-387.

Donham, KJ, J Yeggy, and RR Dauge. 1985. Chemical and physical parameters of liquid manure from swine confinement facilities: Health implications for workers, swine and the environment. Agricultural Wastes 14:97-113.

—. 1988. Production rates of toxic gases from liquid manure: Health implications for workers and animals in swine buildings. Bio Wastes 24:161-173.

Donham, KJ, DC Zavala, and JA Merchant. 1984. Acute effects of work environment on pulmonary functions of swine confinement workers. Am J Ind Med 5:367-375.

Dosman, JA, BL Graham, D Hall, P Pahwa, H McDuffie, M Lucewicz, and T To. 1988. Respiratory symptoms and alterations in pulmonary function tests in swine producers in Saskatchewan: Results of a survey of farmers. J Occ Med 30:715-720.

Douglas, JDM. 1995. Salmon farming: Occupational health in a new rural industry. Occup Med 45:89-92.

Douglas, JDM and AH Milne. 1991. Decompression sickness in fish farm workers: A new occupational hazard. Br Med J 302:1244-1245.

Durning, AT and HB Brough. 1992. Reforming the livestock economy. In State of the World, edited by LR Brown. London: WW Norton & Company.

Erlich, SM, TR Driscoll, JE Harrison, MS Frommer, and J Leight. 1993. Work-related agricultural fatalities in Australia, 1982-1984. Scand J Work Environ Health 19:162-167.

Feddes, JJR and EM Barber. 1994. Agricultural engineering solutions to problems of air contaminants in farm silos and animal buildings. In Agricultural Health and Safety: Workplace, Environment, Sustainability, edited by HH McDuffie, JA Dosman, KM Semchuk, SA Olenchock and A Senthilselvan. Boca Raton, FL: CRC Press.

Ferguson, IR and LRC Path. 1993. Rats, fish and Weil’s disease. Safety and Health Practitioner :12-16.

Food and Agriculture Organization (FAO) of the United Nations. 1965. Farm Implements for Arid and Tropical Regions. Rome: FAO.

—. 1995. The State of the World Fisheries and Aquaculture. Rome: FAO.

Fretz, P. 1989. Injuries from farm animals. In Principles of Health and Safety in Agriculture, edited by JA Dosman and DW Crockcroft. Boca Raton, FL: CRC Press.

Froehlich, PA. 1995. Engineering Control Observations and Recommendations for Insect Rearing Facilities. Cincinnati, OH: NIOSH.

Gillespie, JR. 1997. Modern Livestock and Poultry Production. New York: Delmar Publishers.

Gorhe, DS. 1983. Draught animal power vs mechanization. Asian Livestock VIII:90-91.

Haglind, M and R Rylander. 1987. Occupational exposure and lung function measurements among workers in swine confinement buildings. J Occup Med 29:904-907.

Harries, MG and O Cromwell. 1982.Occupational allergy caused by allergy to pig’s urine. Br Med J 284:867.

Heederick, D, R Brouwer, K Biersteker, and J. Boleij. Relationship of airborne endotoxin and bacteria levels in pig farms with lung function and respiratory symptoms of farmers. Intl Arch Occup Health 62:595-601.

Hogan, DJ and P Lane. 1986. Dermatologic disorders in agriculture. Occup Med: State Art Rev 1:285-300.

Holness, DL, EL O’Glenis, A Sass-Kortsak, C Pilger, and J Nethercott. 1987. Respiratory effects and dust exposures in hog confinement farming. Am J Ind Med 11:571-580.

Holness, DL and JR Nethercott. 1994. Acute and chronic trauma in hog farmers. In Agricultural Health and Safety: Workplace, Environment, Sustainability, edited by HH McDuffie, JA Dosman, KM Semchuk, SA Olenchock, and A Senthilselvan. Boca Raton, FL: CRC Press.

Iowa Department of Public Health. 1995. Sentinel Project Research Agricultural Injury Notification System. Des Moines, IA: Iowa Department of Public Health.

Iverson, M, R Dahl, J. Korsgaard, T Hallas, and EJ Jensen. 1988. Respiratory symptoms in Danish farmers: An epidemiological study of risk factors. Thorax 48:872-877.

Johnson, SA. 1982. Silkworms. Minneapolis, MN: Lerner Publications.

Jones, W, K Morring, SA Olenchock, T Williams, and J. Hickey. 1984. Environmental study of poultry confinement buildings. Am Ind Hyg Assoc J 45:760-766.

Joshi, DD. 1983. Draught animal power for food production in Nepal. Asian Livestock VIII:86-87.

Ker, A. 1995. Farming Systems in the African Savanna. Ottawa,Canada: IDRC Books.

Khan, MH. 1983. Animal as power source in Asian agriculture. Asian Livestock VIII:78-79.

Kiefer, M. 1996. Florida Department of Agriculture and Consumer Services Division of Plant Industry, Gainesville, Florida. Cincinnati, OH: NIOSH.

Knoblauch, A, B Steiner, S Bachmann, G Trachsler, R Burgheer, and J Osterwalder. 1996. Accidents related to manure in eastern Switzerland: An epidemiological study. Occup Environ Med 53:577-582.

Kok, R, K Lomaliza, and US Shivhare. 1988. The design and performance of an insect farm/chemical reactor for human food production. Canadian Agricultural Engineering 30:307-317.

Kuo, C and MCM Beveridge. 1990. Mariculture: Biological and management problems, and possible engineering solutions. In Engineering for Offshore Fish Farming. London: Thomas Telford.

Layde, PM, DL Nordstrom, D Stueland, LB Wittman, MA Follen, and KA Olsen. 1996. Animal-related occupational injuries in farm residents. Journal of Agricultural Safety and Health 2:27-37.

Leistikow, B Donham, JA Merchant, and S Leonard. 1989. Assessment of U.S. poultry worker respiratory risk. Am J Ind Med 17:73-74.

Lenhart, SW. 1984. Sources of respiratory insult in the poultry processing industry. Am J Ind Med 6:89-96.

Lincoln, JM and ML Klatt. 1994. Preventing Drownings of Commercial Fishermen. Anchorage, AK: NIOSH.

MacDiarmid, SC. 1993. Risk analysis and the importation of animals and animal products. Rev Sci Tech 12:1093-1107.

Marx, J, J Twiggs, B Ault, J Merchant, and E Fernandez-Caldas. 1993. Inhaled aeroallergen and storage mite reactivity in a Wisconsin farmer nested case-control study. Am Rev Respir Dis 147:354-358.

Mathias, CGT. 1989. Epidemiology of occupational skin disease in agriculture. In Principles of Health and Safety in Aagriculture, edited by JA Dosman and DW Cockroft. Boca Raton, FL: CRC Press.

Meadows, R. 1995. Livestock legacy. Environ Health Persp 103:1096-1100.

Meyers, JR. 1997. Injuries among Farm Workers in the United States, 1993. DHHS (NIOSH) Publication No. 97-115. Cincinnati, OH: NIOSH.

Mullan, RJ and LI Murthy. 1991. Occupational sentinel health events: An up-dated list for physician recognition and public health surveillance. Am J Ind Med 19:775-799.

National Institute for Occupational Safety and Health (NIOSH). 1993. Injuries among Farm Workers in the United states. Cincinnati, OH: NIOSH.

—. 1994. Request for Assistance in Preventing Organic Dust Toxic Syndrome. Washington, DC: GPO.

National Institutes of Health (NIH). 1988. Institutional Administrator’s Manual for Laboratory Animal Care and Use. Washington, DC: GPO.

National Research Council (NRC). 1989. Alternative Agriculture: Committee on the Role of Alternative Farming Methods in Modern Production Agriculture. Washington, DC: National Academy Press.

National Safety Council. 1982. Accident Facts. Chicago, IL: National Safety Council.

—. 1985. Electrofishing. NSC data sheet I-696-85. Chicago, IL: National Safety Council.

Nesheim, MC, RE Austic, and LE Card. 1979. Poultry Production. Philadelphia, PA: Lea and Febiger.

Olenchock, S, J May, D Pratt, L Piacitelli, and J Parker. 1990. Presence of endotoxins in different agricultural environments. Am J Ind Med 18:279-284.

O’Toole, C. 1995. Alien Empire. New York: Harper Collins Publishers.

Orlic, M and RA Leng. 1992. Prelimenary Proposal to Assist Bangladesh to Improve Ruminant Livestock Productivity and Reduce Methane Emissions. Washington, DC: US Environmental Protection Agency, Global Change Division.

Panti, NK and SP Clark. 1991. Transient hazardous conditions in animal building due to manure gas release during slurry mixing. Applied Engineering in Agriculture 7:478-484.

Platt, AE. 1995. Aquaculture boosts fish catch. In Vital Signs 1995: The Trends that Are Shaping our Future, edited by LR Brown, N Lenssen, and H Kane. New York: WW Norton & Company.

Pursel, VG, CE Rexroad, and RJ Wall. 1992. Barnyard biotchnology may soon produce new medical therapeutics. In New Crops, New Uses, New Markets: Industrial and Commercial Products from U.S. Agriculture: 1992 Yearbook of Agriculture Washington, DC: USDA.

Ramaswami, NS and GL Narasimhan. 1982. A case for building up draught animal power. Kurushetra (India’s Journal for Rural Development) 30:4.

Reynolds, SJ, KJ Donham, P Whitten, JA Merchant, LF Burmeister, and WJ Popendorf. 1996. A longitudinal evaluation of dose-response relationships for environmental exposures and pulmonary function in swine production workers. Am J Ind Med 29:33-40.

Robertson, MH, IR Clarke, JD Coghlan, and ON Gill. 1981. Leptospirosis in trout farmers. Lancet: 2(8247)626-627.

Robertson, TD, SA Ribeiro, S Zodrow, and JV Breman. 1994. Assessment of Strategic Livestock Feed Supplementation as an Opportunity for Generating Income for Small Scale Dairy Producers and Reducing Methane Emissions in Bangladesh. Washington, DC: US Environmental Protection Agency.

Rylander, R. 1994. Symptoms and mechanisms: Inflammation of the lung. Am J Ind Med 25:19-24.

Rylander, R, KJ Donham, C Hjort, R Brouwer, and D Heederik. 1989. Effects of exposure to dust in swine confinement buildings: A working group report. Scand J Work Environ Health 15:309-312.

Rylander, R and N Essle. 1990. Bronchial hyperactivity among pig and dairy farmers. Am J Ind Med 17:66-69.

Rylander, R, Y Peterson, and KJ Donman. 1990. Questionnaire evaluating organic dust exposure. Am J Ind Med 17:121-128.

Rylander, R and R Jacobs. 1994. Organic Dusts: Exposure, Effects and Prevention. Chicago, IL: Lewis Publishing.
Safina, C. 1995. The world’s imperiled fish. Sci Am 272:46-53.

Scherf, BD. 1995. World Watch List for Domestic Animal Diversity. Rome: FAO.

Schmidt, MJ. 1997. Working elephants. Sci Am 279:82-87.

Schmidt, JO. 1992. Allergy to venomous insects. In The Hive and the Honey Bee, edited by JM Graham. Hamilton: DaDant & Sons.

Shumacher, MJ and NB Egen. 1995. Significance of Africanized bees on public health. Arch Int Med 155:2038-2043.

Sherson, D, I Hansen, and T Sigsgaard. 1989. Occupationally related respiratory symptoms in trout-processing workers. Allergy 44:336-341.

Stem, C, DD Joshi, and M Orlic. 1995. Reducing Methane Emissions from Ruminant Livestock: Nepal prefeasibility Study. Washington, DC: US Environmental Protection Agency, Global Change Division.

Sweeten, JM. 1995. Odor measurement technology and applications: A state-of-the-art review. In Seventh International Symposium on Agricultural and Food Processing Wastes: Proceedings of the 7th International Symposium, edited by CC Ross. American Society of Agricultural Engineering.

Tannahill, R. 1973. Food in History. New York: Stein and Day.

Thorne, PS, KJ Donham, J Dosman, P Jagielo, JA Merchant, and S Von Essen. 1996. Occupational health. In Understanding the Impacts of Large-scale Swine Production, edited by KM Thu, D Mcmillan, and J Venzke. Iowa City, IA: University of Iowa.

Turner, F and PJ Nichols. 1995. Role of the epithelium in the response of the airways. Abstract for the 19th Cotton and Other Organic Dust Research Conference, 6-7 January, San antonio, TX.

United Nations Development Programme (UNDP). 1996. Urban Agriculture: Food, Jobs, and Sustainable Cities. New York: UNDP.

US Department of Agriculture (USDA). 1992. Agricultural Waste Management Field Handbook. Washington, DC: USDA Soil Conservation Service.

—. 1996a. Livestock and Poultry: World Markets and Trade. Circular Series FL&P 1-96. Washington DC: USDA Foreign Agricultural Service.

—. 1996b. Dairy: World Markets and Trade. Circular Series FD 1-96. Washington DC: USDA Foreign Agricultural Service.

—. 1997. Poultry Production and Value, 1996 Summary. Washington, DC: National Agricultural Statistics Service.

van Hage-Hamsten, M, S Johansson, and S Hogland. 1985. Storage mite allergy is common in a farming population. Clin Allergy 15:555-564.

Vivian, J. 1986. Keeping Bees. Charlotte, VT: Williamson Publishing.

Waller, JA. 1992. Injuries to farmers and farm families in a dairy state. J Occup Med 34:414-421.

Yang, N. 1995. Research and development of buffalo draught power for farming in China. Asian Livestock XX:20-24.

Zhou, C and JM Roseman. 1995. Agriculture-related residual injuries: Prevalence, type, and associated factors among Alabama farm operators, 1990. Journal of Rural Health 11:251-258.

Zuehlke, RL, CF Mutel, and KJ Donham. 1980. Diseases of Agricultural Workers. Iowa City, IA: Department of Preventive Medicine and Environmental Health, University of Iowa.