Estimation of in vivo digestibility with the laying hen by an in vitro method using the intestinal fluid of the pig

1. Dry matter and crude protein (nitrogen x 6.25) digestibility of four poultry diets determined by an in vitro method using the intestinal fluid of pigs was significantly correlated with corresponding in vivo digestibility values obtained with hens. 2. The intestinal fluid could be lyophilized and stored for at least 35 d without losing its activity on digestion.