Agriculture Reference
In-Depth Information
efficiency. This trend evolved to include all main meat bird species (turkeys, ducks)
and was rapidly embraced by the pig industry. This revolution in the way animals
were raised created a need for engineered buildings and systems for providing the
necessary environment and the support infrastructure for feed storage and delivery,
water quality control, supply and distribution, artificial lighting, and enhanced envi-
ronment control across a broad expanse of climatic zones.
The economic advantages achieved from increased production efficiency sparked
a new market system, the vertically integrated animal feeding operation (AFO), and
was pioneered by a few individuals first in the broiler chicken industry. This evolved
rapidly, and within a generation the majority of U.S. meat bird production has
become dominated by so-called integrator companies. Mechanization of production
components, including feed and water distribution, animal handling, and environ-
ment control was a key characteristic of this new production method. Automation,
however, has only slowly been adopted and in only particular niches of the modern
animal production system supply chain. In this article, the main features of automa-
tion and control in modern intensive livestock and poultry production are covered.
8.2 HOUSINGSYSTEMS
With the exception of beef cattle held on feedlots or pasture, the majority of poultry
and livestock are raised indoors. Modern structures for livestock and poultry house
large numbers of animals—for example, animal numbers per building are typically
about 1200, 25,000, and 250,000 for swine, broilers, and laying hens, respectively.
Operations of these structures are typically automated and/or intensely mechanized
and managed in areas that include: environment control, lighting control, feed and
water delivery, animal or egg harvesting, and manure management.
8.2.1 E
NVIRONMENTAL
C
ONTROL
S
YSTEMS
Although structures were used initially to shelter animals from the most extreme
events, the simple act of aggregating a high density of animals into a closed space
creates several significant problems because the animals produce heat, moisture,
and various gases including carbon dioxide from respiration, ammonia from feces
decomposition, and variable but generally high dust concentrations. Accordingly,
ventilation and heating systems have been developed to maintain interior environ-
ment to conditions vastly better than can be expected outdoors. Early systems typi-
cally included open-sided buildings, often with an outside area for animals to access,
and then evolved to curtain-sided buildings in which the animals remained indoors,
and the environment was controlled predominantly via so-called natural ventilation
created by either wind, or stack effects, or both. This allowed for more uniform tem-
perature control, which is critical for efficient feed conversion—feed is the single
largest expense in producing meat animals, substantially greater than energy, labor,
and capital costs. Control of natural ventilation was an early area for automated envi-
ronment control in animal production. Various methods for mechanizing and con-
trolling curtains and doors to adjust airflow through a building have been developed,
primarily based on temperature control.
