Bielorai, R., Div. Anim. Nutrit., Volcani Cent., Agric. Res. Organ., Bet Dagan, Israel
Tamir, M., Div. Anim. Nutrit., Volcani Cent., Agric. Res. Organ., Bet Dagan, Israel
Alumot, E., Div. Anim. Nutrit., Volcani Cent., Agric. Res. Organ., Bet Dagan, Israel
Bar, A.
Hurwitz, S.

Net absorption and digestion of protein were evaluated in chicks fed heated soybean meal (HS) and 3 levels of raw soybean meal (RS), using 91Y as a reference substance. In HS fed chicks a cumulative digestion of 90% was attained: 70% in the duodenum and an additional 20% in the remaining segments. In the duodenum of the RS fed chicks an extensive nitrogen secretion, proportional to the RS levels in the diets, occurred. The secreted nitrogen was reabsorbed in the upper jejunum. The net digestion values in the duodenum were also proportional to the RS levels in the diets. When the duodenal N secretion is taken into account it is concluded that, as in chicks fed HS, most of the food protein was digested in the duodenum of the RS fed chicks. The 20% difference in the cumulative net digestion between the HS and RS groups is probably the result of inhibition of proteolysis in segments beyond the duodenum. The jejunum is the main site of absorption in HS and RS fed chicks. The absorption process in this segment is enhanced and not impaired by RS. The 20% difference in the overall protein absorption between the HS and RS groups is probably the result of a corresponding inhibition in digestion beyond the duodenum.