Use of Industrial Wastes in Poultry
Feeding
C.   W.   CARRICK
Professor, Department of Poultry Husbandry
Purdue University
Lafayette, Indiana
Industrial wastes have long been used in feeding poultry and other
animals. Among the earliest products thus used were meat packing
house products, such as meat scraps and tankage. Later came waste
products from dairy manufacturing plants, including various forms of
buttermilk, skim milk and whey. Most of these early products of animal
origin were regarded primarily for their protein content.
While soybean oil meal and some other vegetable protein products
have not been generally regarded as industrial waste products, they are
secondary products of oil processing. Until recently vegetable proteins
have been looked upon as inferior to animal proteins. It is now known
that much of the bad reputation of some of these products was due to
a lack of certain vitamins and minerals supplied by the animal products
rather than the quality of their protein.
The nutritional value of a protein depends upon the amino acids
yielded upon digestion. The amino acids are the building stones which
combine in certain proportions to form the proteins in body tissues and
secretions. Eleven of these amino acids are considered "essential" for the
growing chicken since no one of them can replace another. There are
a dozen or more other amino acids yielded by proteins which can be
transformed or synthesized in the body and are referred to somewhat
unappropriately as "non-essential".
Among the various amino acids there are four which need to be con¬
sidered in practical poultry ration formulation. These are arginine,
tryptophan and the sulfur-bearing amino acids methionine and cystine.
When adequately provided, soybean meal will supply enough of all the
amino acids, except methionine and cystine, to give maximum early
growth. Soybean oil meal is the most practical source of amino acids
for poultry rations.
In this area yellow corn is usually the cheapest and most satisfactory
source of energy for poultry rations. Both corn and soybean meal are
deficient in certain necessary vitamins and minerals. The practical prob-
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