ANN 111: Principles of Animal Nutrition and Feed Technology (2+1)

 SOYBEAN MEAL

Soybean meal contains 44% crude protein with all indispensable amino acids except cysteine, methionine whose concentrations are        sub- optimal. It can be fed to all livestock including poultry up to 30% of the ration. The common adulterant includes urea, castor husk and Mahua oil cake. Like other oil seeds, raw soybeans have number of toxic and inhibitory substances. For example, in some species, the long-term use of soybean leads to goiter due to the presence of goitrogenic material. Six protein inhibitors have been identified in soybean; out of these two inhibitors namely Kunitz anti-trypsin inhibitor and Bowman-Birk chymotrypsin inhibitors are practically significant. Trypsin inhibitors especially interferes the protein digestion in monogastric animals. Protein indigestibility affects growth rate, egg production and feed efficiency and also may lead to hypertrophy of pancrease and excess endogenous loss of essential amino acids. Haemogglutinin (Lectin) present in soybean agglutinates red blood cells of rats, rabbits and human except sheep and calves. Lectins are proteins capable of binding carbohydrate moieties in the epithelial cell lining of small intestine, disrupting the brush boarder and reducing the efficiency of absorption. Genistein, a plant estrogen in soybean has the potency of 4 x 10-6 time as that of diethyl stilbestrol. These toxic inhibitory substances and other factors in soybean like saponins can be inactivated by proper heat treatment during processing.

Raw soybean has Goitrogenic material. Six protein inhibitors Kunitz anti-trypsin inhibitor & Bowman-Birk chymotrypsin inhibitors are important. Haemogglutinin agglutinates RBC. Genistein is phyto estrogenic compound. Heat treatment inactivates these anti nutritional properties.