Effects of removal of the forestomach and caecum on the utilization of dietary urea in golden hamsters (Mesocricetus auratus) given two different diets.

1. Surgical removal of the forestomach, the caecum or both the forestomach and the caecum, was performed on growing male golden hamsters (Mesocricetus auratus) given a low-or high-fibre diet. 2. In Expt 1, 18 d after surgery, the hamsters which were given a concentrate before surgery were given an experimental low-fibre diet containing urea or [15N] urea (10 g/kg diet) for 9 d. In Expt 2, 5 d after surgery, the hamsters which were given a forage diet before surgery were adopted to an experimental high-fibre diet containing urea (10 g/kg) and dried Italian ryegrass (Lolium italicum) powder (400 g/kg diet) for 5 d, and 10 d after surgery, given a diet containing [15N]urea (10 g/kg diet) for 9 d. 3. In both experiments, removal of the caecum resulted in a significant lowering of both weight-gain and the digestibility of the dry matter, and removal of the forestomach resulted in a significant decrease of both accumulation of 15N in the body protein and proportion of 15N retained in the body protein as a proportion of the administered dosage. 4. The effect of removal of the caecum on the utilization of [15N] urea was not apparent in Expt 1, but the utilization of [15N] urea was significantly lowered by removal of the caecum in Expt 2. 5. These results suggest that the caecum may play a more important role in food utilization than the forestomach. However, the forestomach of the golden hamster plays a significant role in the utilization of dietary urea. It is presumed that the role of the caecum in the utilization of urea may vary under different dietary conditions.