CONSIDERATIONS IN USING PROTEIN MEALS FOR MONOGASTRIC ANIMALS

Abstract

Protein sources are important in animal feeding to meet nutrient requirements for
digestible amino acids. Generally, protein sources have higher unit cost as compared
to the grain sources that are used mainly to meet energy requirements. The use of
less expensive protein meals mu potentially reduce feed costs and give reasonable
performance but only if formulated correctly. Ingredient price, source, nutrient
levels, bioavailability, anti-nutritional factors, palatability, pellet quality and efl'ect
on animal performance must all be considered. Soybean meal has become the
industry standard to which other protein meals are compared. Soybean marl is rich
in protein and the essential amino acid lysine but is a relatively poor sources of
methionine and cystine. Dehulling of soybean meal improves not only its protein
and amino acid content but its metabolizable and digestible energy content as well.
Soybean meal digestibility is afiected by heat application during processing for oil
extraction. The best soybean meal has precisely enough heat to inactivate anti-
nutritional factors but not essential amino acids. Canola meal and its relative
rapeseed meal are the second most widely used of the protein meals. Canola and
rapeswd meal have a reasonably well balanced amino acid profile but are deficient
in lysine. In general, amino acid digestibility is lower than soybean meal especially
for poultry. Rapeseed meal in particular may also contain the anti-nutritional factor
glucosinolate. This compound and similar ones present result in poor growth,
skeletal abnormalities and off odors in eggs and meat. Cottonseed meal ranks third
among the total oilseed meals produced. Cottonseed meal has a slightly lower
protein content than soybean meal but a much higher and more variable fiber
content. Cottonseed meal has less digestible lysine, methionine, threonine and
tryptophan than soybean meal. Gossypol is a recognized toxic component of
cottonseed meal that can cause cardiac edema, dyspnea, weakness and anorexia.
Corn gluten meal, peanut meal, fishmeal, meat and bone meal, sunflower meal,
copra meal and others are all potentially useful in poultry feeds. Each has both
beneficial and limiting traits associated with them. This paper will discuss the
nutritional and economic considerations for using various protein meals in poultry
feed.