Manure, Toxic Ammonia, Dead Birds

Manure is everywhere in the caged layer complex. Toxic ammonia rises from the decomposing uric acid in the manure pits beneath the cages to produce a painful corneal ulcer condition in chickens known as “ammonia burn,” a keratoconjunctivitis that can lead to blindness. It facilitators chronic respiratory diseases such as infectious bronchitis, caused by an airborne virus. Ammonia injures the mucous membranes of the upper respiratory tract making it easy for disease organisms to invade and colonize the lungs, air sacs and livers of exposed birds. It enters the blood causing immunosuppression, which further encourages diseases Studies of the effect of ammonia on eggs suggest that even at low concentrations significant quantities of ammonia can be absorbed into the egg. The huge chicken flocks produce tons of manure and millions of dead birds. According to a researcher, a one-million- hen complex produces 125 tons of wet manure a day.

Broiler chickens are raised on the floor and slaughtered as babies; thus houses can be cleaned out occasionally. However, laying hens are confined in the same building for one or two years in tightly stacked cages, which raises the question of how to remove the manure and the corpses with-out disturbing production. Mason and Singer explain the manure solution in Animal Factories: “Producers discovered that they could confine layer hens in wire-mesh cages suspended over a trench to collect droppings. The manure pile could be cleaned out without bothering the hens above. At first, producers placed their birds one to each cage. When they found that birds were cheaper than wire and buildings, crowded cages in crowded houses became the rule.” Between 1955 and 1975, flock size on a typical egg farm in the United States rose from twenty thousand to eighty thousand birds per house. Between 1975 and 1992, it rose to 125 thousand or more birds per house. According to Bell, “Today in-line complexes include eight or more, [with] 100,000 or more [hens per house], environmentally con-trolled hen houses with at least four decks of cages, belt or high rise manure handling systems, often a feed mill, and an egg room for seven-day-per-week packing. Pullets [imma-ture hens] are reared separately. Practically all new farms would be described as complexes” in which “production and processing [are] in close proximity to one another, and usually includes linkage of the two with egg conveyor belts.”

Despite the fact that the manure fumes and rotting car-casses force workers in the houses to wear gas masks, the egg industry claims that the battery cage is more hygienic than the free-range systems and floor systems of the past, because the hens have less direct contact with their own droppings, which are (in principle) deflected by a device to the pits beneath the tiers of cages. The industry does not want to give up cages, citing manure build-up as a reason. “In fact laying
chickens will need more drugs to stay alive.” By Karen Davids ph.d


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