In a companion study, the research team determined nitrogen balance in 36 pigs fed diets that induced different ileal endogenous nitrogen losses. The diet was fed at 2.7 times the metabolizable energy level needed for maintenance and was restricted to 88% of the requirement for ileal digestible lysine. The results indicated that greater excretion of nitrogen in the urine is associated with higher ileal endogenous nitrogen losses and trypsin inhibitor levels in the soy products.

Grala, W. and co-workers. 1998. Nitrogen utilization in pigs fed diets with soybean and rapeseed products leading to different ideal endogenous nitrogen losses. J. Anim. Sci. 76:569-577.