Role of the Cecum in the Utilization of Raw Soybean in Chicks

Abstract

In previous work, depression of intestinal proteolysis was observed in young chicks fed a raw soybean diet. In the present study nitrogen balances performed on chicks from one to 7 weeks of age revealed smaller differences in nitrogen retention when raw and heated soybean diets were fed than was expected. This difference however, did not improve with age and other parts of the intestinal tract, including the cecum, were therefore tested for proteolytic activity. High proteolytic activity was noted in ceca of chicks up to 4 weeks old fed heated and raw soybean diets; whereas during the sixth week the enzyme activity decreased markedly with heated soybean; a slight depression occurred with the raw soybean diet. An increase of cecal proteolysis was observed when 8-week-old chicks were transferred from a heated to raw soybean diet. The contribution of the cecum to body weight gains, feed efficiency and nitrogen retention was investigated by cecoctomy. Chicks with no cecum that were fed raw soybean gained less weight, showed lower feed efficiency, and retained less nitrogen than sham-operated chicks. With heated soybean the removal of ceca increased the feed utilization somewhat. It appears that cecal proteolysis and subsequent nitrogen absorption compensate partly for inhibited proteolysis in the small intestine.