Sanitary risk associated with large-scale livestock production involves microbiological contamination of air and water. Litter(bedding), livestock excreta, feed, animals and farm workers aresources of microbiological contamination of air in livestock buildings.The composition of air microflora depends on the livestock housingdesign, type of livestock, livestock size, air ventilation type, airtemperature and humidity, and the lighting system. Microbiological aircontamination can reach the level of 105 CFU/m3 of bacteria and 104 CFU/m3of fungi in swine buildings. 1 LU of pigs (sows) produces around 1.57CFU (colony forming units)/h (around 0.12 CFU/h per animal) and around0.02 CFU/h.
Thereare multiple infectious, toxic and allergenic microorganisms present incontaminated air, which pose a serious threat for exposed individuals.Microorganisms suspended in indoor air are emitted to the open air. Forexample, a poultry battery facility of 50,000 laying hens releases52.5-90.7 billion bacteria and around 0.31-5.5 billion fungi to the openair, many of which are pathogenic (such as Erysipelothrix rhusiopathiae, Mycobacterium tuberculosis, streptococcus and staphylococcus bacteria, foot-and-mouth disease virus, parasite eggs, Cladosporium, Alternaria, Penicillium and Fusariumfungi). They can cause serious infectious diseases in animals andhumans as they can be carried by the wind over large distances.
Absenceof natural biothermal purification processes in slurry significantlyprolongs the survival period of microorganisms: up to 457 days for Mycobacterium tuberculosis, up to 157 days for Erysipelothrix rhusiopathiae, up to 158 days for paratyphoid fever bacteria, up to 174 days for Brucellosisbacteria, and up to 192 days for foot and mouth disease virus. Apartfrom these pathogens, slurry was found to contain faecal streptococci, Escherichia coli, pathogenic streptococci bacteria, Staphylococcus sp., fungi and parasite eggs (such as cestoda). Slurry can contain as many as 150 pathogens which can be dangerous for human. Salmonella, Listeria, Giardia and E. colibacteria are responsible for 90% of food poisonings and waterbornebacterial infections. Pathogens in contaminated surface water can bedangerous for people who bathe in sea water or eat sea food.
Applicationof antibiotics is another major problem. Under the Polish foodregulations based on Regulation (EC) No 1831/2003 of the EuropeanParliament and of the Council on additives for use in animal nutrition,antibiotics are banned as additives to animal feed since 1 January 2006;however, they are routinely used in veterinary practice. Note thatincorrect or improper use of antibiotics, especially in large-scaleanimal rearing installations, leads to the development of bacterialstrains, including pathogenic ones, resistant to antibiotics. Over 90%of Staphylococcus aureus isolates from large-scale livestockfarms in the United States were show to be resistant to penicillin, andthe number of Staphylococcus isolates resistant to methicillin hasincreased from 2.4% to 29% between 1975 and 1991. Some of these bacteriacan be carried over to humans through infected meat or in directcontact with animals (Campylobacter sp., Salmonellasp.). It is estimated that livestock waste is the source of as much as75% of antibiotics used in large-scale livestock farms, theseantibiotics can permeate to the natural environment surrounding thelivestock production installations and affect aquatic and soilmicroflora.
Highrat populations in livestock production installations is another issue.In large-scale livestock production, livestock buildings occupy largeareas which can be infested by rats.Rats are known to carry a numberof dangerous diseases and contribute to livestock-biocenosis orbiocenosis-livestock transmission of pathogens and parasites.