Table 2.
The quality of included studies.
| Studies | Year | A | B | C | D | E | F | Score |
|---|---|---|---|---|---|---|---|---|
| Chen et al. | 2018 | Y | Y | N | N | Y | Y | 4 |
| Zhou et al. | 2017 | Y | N | N | N | Y | Y | 3 |
| Zhai et al. | 2017 | Y | Y | N | N | Y | Y | 4 |
| Zhou et al. | 2017 | Y | N | N | N | Y | Y | 3 |
| He et al. | 2016 | Y | N | N | N | Y | Y | 3 |
| Yu et al. | 2015 | Y | Y | N | N | Y | Y | 3 |
| Yu et al. | 2014 | Y | Y | N | N | Y | Y | 4 |
| Chen et al. | 2009 | Y | N | N | N | Y | Y | 3 |
| Genade et al. | 2008 | Y | N | N | N | Y | N | 2 |
| Lochner et al. | 2006 | Y | N | N | N | Y | N | 2 |
| Sahna et al. | 2005 | Y | N | N | N | Y | N | 2 |
| Sahna et al. | 2002 | Y | Y | N | N | Y | Y | 4 |
| Lee et al. | 2002 | Y | Y | N | N | Y | Y | 4 |
| Lagneux et al. | 2000 | Y | N | N | N | Y | N | 2 |
| Nduhirabandi et al. | 2010 | Y | N | N | N | Y | Y | 3 |
A: peer-reviewed publication; B: random allocation to groups; C: blinded assessment of outcomes; D: sample size calculation; E: compliance with animal welfare regulations; F: a statement of a potential conflict of interest; Y: yes; N: no.