Castor Bean Meal as a Protein Source for Chickens: Detoxification and Determination of Limiting Amino Acids

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Abstract
A series of studies were carried out with commercially available castor bean meal (CBM), providing approximately 40% protein, to determine its usefulness as a protein source for growing chickens. It was found that hot water extraction was the best procedure, among several tried, for removal of most, if not all, of the growth-depressing components of CBM. Following hot water extraction, it was determined that lysine was the first, and tryptophan the second limiting amino acid. Supplementing CBM with both lysine and tryptophan gave growth rates of chicks as good as those obtained with methionine-supplemented isolated soy protein and markedly improved the net protein utilization value (NPU), but the NPU value was still inferior to that obtained with methionine-supplemented isolated soy protein. It is concluded that hot water-extracted CBM, properly supplemented with the limiting amino acids lysine and tryptophan is an acceptable protein source for chick diets.