| Publication/Reference number | Study | Birds observeda | Species (breed) | Days on substrateb | Enclosure area (m2)c | Stocking densityd | Animals/m2 /daye | Substrate area (m2)f | Substrate depth (cm) |
|---|---|---|---|---|---|---|---|---|---|
| Jong et al., 2007 (38) | 1 | 16 | Layer | 21.00 | 6.75 | 0.59 | 0.03 | 1.13–2.25 | 5.0 |
| Sanotra et al., 1995 (39) | 2 | 12 | Layer | 0.04 | 0.41 | 4.94 | 118.52 | 0.03–0.04 | 4.0 |
| Shields et al., 2004 (40) | 3 | 52 | Broiler | 4.00 | 2.31 | 0.87 | 0.22 | 0.37–0.82 | 10.0 |
| Villagra et al., 2014 (41) | 4 | 32 | Broiler | 0.05 | 4.00 | 2.00 | 41.14 | 1.00 | 15.0 |
| Shields et al., 2005 (42) | 5 | 60 | Broiler | 49.00 | 9.30 | 1.08 | 0.02 | 4.65 | 2.5 |
| Toghyani et al., 2010 (43) | 6 | 80 | Broiler | 42.00 | 5.76 | 3.47 | 0.08 | 1.44 | 2.0 |
| van Liere et al., 1990 (44) | 7 | 23 | Layer | 5.00 | 3.90 | 1.54 | 0.31 | 0.36 | 12.0 |
| Hogan and Vestergaard, 1992 (45) | 8 | 10 | Jungle Fowl | 0.02 | 0.48 | 4.17 | 171.43 | 0.12 | 2.0 |
| Petherick and Duncan, 1989 (46) | 9 | 48 | Layer | 0.02 | 5.76 | 1.04 | 50.00 | 0.13 | 4.0 |
| Guinebretière et al., 2014 (33) | 10 | 60 | Layer | 4.00 | 1.05 | 3.81 | 0.95 | 0.49 | 3.0 |
a
Total number of birds observed in each study (some studies picked focal birds).
b
Number of days birds were allowed access to tested substrates (in enclosure area). Small numbers represent studies that moved animals into a separate area to observe.
c
The size of the total enclosure, encompassing all substrate areas, in m2.
d
Animals per m2; Stocking density = animals per group (not shown; some studies used focal birds) ÷ enclosure area (m2).
e
Proxy for degree of substrate soiling (higher numbers indicate more soiling); animals/m2/day = stocking density ÷ days on substrate.
f
The area (m2) occupied by one substrate within the enclosure.