Table 1.

Ammonia level (mean ± 1 SD) in cages holding 5 male or 5 female mice at 1 to 16 d after cage change

Time (d) after cage change	Ammonia level in cages holding 5 mice (no. of cages evaluated)
	Male	Female
1	1.4 ± 0.2 (10)	14. ± 0.2 (10)
2	1.7 ± 0.4 (10)	1.5 ± 0.3 (10
3	2.0 ± 0.7 (12)	1.8 ± 0.3 (12)
4	2.4 ± 0.8 (14)	2.0 ± 0.9 (14)
5	2.5 ± 0.9 (14)	2.2 ± 0.8 (14)
6	2.6 ± 0.8 (14)	2.3 ± 0.8 (14)
7	2.4 ± 0.9 (14)	2.3 ± 0.9 (14)
8	2.6 ± 0.8 (14)	2.3 ± 0.9 (14)
9	2.9 ± 0.8 (14)	2.3 ± 1.0 (14)
10	2.9 ± 0.7 (8)	2.6 ± 0.8 (4)
11	3.3 ± 0.7 (14)	2.6 ± 0.9 (14)
12	3.3 ± 0.6 (12)	2.5 ± 1.0 (12)
14	3.5 ± 0.6 (14)	2.8 ± 0.9 (14)
16	3.3 ± 0.7 (11)	2.7 ± 0.5 (6)

Ammonia level codes: 1, less than 1 ppm ammonia (color of indicator disk, yellow); 2, 1–25 ppm (light green); 3, 25–50 ppm (medium green); and 4, more than 50 ppm (dark blue).