Figure 2.

Intracage ammonia measurement techniques. (A) Colorimetric strips were torn into approximately 1-cm segments and inserted through the cage's water bottle port by using hemostats. (B) Colored reagent tubes attached to a sampling pump were inserted 4 in. into cages, through predrilled holes located 1 in. from the cage bottom. (C) The photoionisation detector was connected to a hydrophobic filter, and a gas sampling line attached to a blunted 16-gauge, 1.5-in. needle. The blunted needle probe was inserted fully into cages, through predrilled holes.