Table 1. Characteristics of the animal studies included in the meta-analysis.

First author (year)	Language	n	Mode of intervention	Period of PC(day)	Source of indicators	Outcome indicators
Su-Jin2009 [14]	English	10	Feed	<30d	Tissue	2.3.6
Mi-Ok Shin2010 [15]	English	6	Feed	<30d	Tissue	1
Xiayuan2010 [16]	Chinese	8	Gavage	<30d	Serum	1.2
Adem Guler2011 [17]	English	8	Gavage	<30d	Tissue	1.2.3.4
HUANG Qi-liang2011 [18]	English	10	Gavage	≥30d	Serum	1.2
Lijianling2011 [19]	Chinese	10	Gavage	<30d	Tissue	1.2
Osama M.Ashour2011 [20]	English	12	Gavage	<30d	Tissue	1.2.5.6
Xielimei2011 [21]	Chinese	10	Gavage	≥30d	Tissue	1.2
Soo-Kyong Choi2012 [22]	English	8	Feed	<30d	Tissue	2.3.5
Vijayakumar2012 [23]	English	6	Gavage	<30d	Tissue	2.3.5.6
Wangweifen2012 [24]	Chinese	10	Gavage	<30d	Tissue	1.2
Xiao GENG2012 [25]	English	8	Gavage	<30d	Tissue	1.2
Yu Deng2012 [26]	English	8	Gavage	<30d	Tissue	1.2.3.5
zhangxuan2012 [27]	English	16	Gavage	<30d	Tissue	1.2.3.6
zhaopeng2012 [28]	Chinese	12	Gavage	≥30d	Serum	1.2.3
Bailijun2013 [29]	Chinese	5	Gavage	<30d	Serum	1.2.3.6
Dingyusong2013 [30]	Chinese	10	Gavage	≥30d	Tissue	1.2
Hanaa A2013 [31]	English	6	Gavage	≥30d	Tissue	1.2.3.4
Jiangyanfei2013 [32]	Chinese	12	Gavage	≥30d	Serum	1.2
Miaozhiru2013 [33]	Chinese	10	Gavage	≥30d	Serum	1.2.3.5
E Bakar2014 [34]	English	7	Gavage	<30d	Tissue	1.2.4.5
Gaolu2014 [35]	Chinese	10	Gavage	≥30d	Serum	1.2.3.6
Hua Zhang2014 [36]	English	10	Gavage	≥30d	Tissue	1.2.5.6
Juan Xiao2014 [37]	English	10	Gavage	<30d	Serum	1.2.3
Noorah2014 [38]	English	10	Gavage	<30d	Tissue	2.6
Tingting Ren2014 [39]	English	8	Gavage	≥30d	Serum	2.5
Wangcheng2014 [40]	Chinese	10	Gavage	≥30d	Tissue	1.2.4.5
Ying GAO2014 [41]	English	10	Gavage	≥30d	Tissue	1.2.3
Esrafil Mansouri2015 [42]	English	10	Gavage	<30d	Serum	1.2.3.6

Note: n = number of experimental animals; 1 = malondialdehyde, 2 = superoxide dismutase, 3 = glutathione peroxidase, 4 = total antioxidative capacity, 5 = glutathione, and 6 = catalase.