MISSION IMPOSSIBLE:
Dispose Animal Wastes
E. PAUL TAIGANIDES, Professor
Agricultural Pollution Control Research Laboratory
Agricultural Engineering Department
Ohio State University
Columbus, Ohio
INTRODUCTION
Thanks to unprecedented advances in agricultural sciences and technology, we
are beginning to see in agriculture what has already occurred in the industrial sector;
the integration of all operations into a comprehensive input-output system of food
and fiber production. This means we are beginning to raise animals in an "assembly-
line" type of system. Animals can be grown in confinement with automatically
regulated environment, with automatic feeders, automatic waterers, automatic immunization, and with automatic egg and milk removal. Research and development programs have been initiated to produce analogous waste management technology with
the ultimate aim of automatic manure handling, treatment and disposal.
Recent developments in the management of animal wastes parallel new developments and trends in animal production patterns.
ANIMAL PRODUCTION PATTERNS
In the United States of America, a transition from pasture to confinement
"mass-production" has helped meet additional demands for pork and eggs without
an increase in the number of hens, pigs and dairy cows during the last 20 years. Since
1950 the United States' population has been increasing at an average rate of three
million additional people per year. However, during the same period, the number of
hogs on farms remained at about 50 million, the number of chickens decreased from
400 to 350 million in 1969, and the number of cows kept for milk decreased from 35
million in 1950 to about 20 million today (1).
"Industrialization" became possible first in egg production. From a peak of 5.8
million farms reporting chickens in 1935, the number dropped to 1.2 million farms in
1964, and it is now estimated to be about 0.6 million. Last year, 5 2 per cent of all laying
hens in the United States were raised in cages. In California, the leading egg producing
state, 97 per cent of the layers are in cages.
Although changes in swine and dairy cattle production have not been as extensive as in poultry, similar trends have been established. The number of farms with
milk cows decreased from about 3.5 million in 1950 to less than one million today.
In 1950, three million farms reported an average of 20 pigs per farm. Today there are
less than one million farms on which pigs are grown, yet the number of pigs sold in
the USA last year exceeded 80 million head.
In the broiler and beef cattle industry efficiency of production alone could not
keep up with the increasing demand for meat. The number of cattle raised for meat
increased at the rate of four million per year during the last ten years; broiler production went from 0.63 billion birds sold in 1950 to about 2.6 billion in 1967. In 1960
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