Table 1.

Characteristics of studies included in the meta-analysis.

Study (Authors and Year)	Breed	Sex	Country	HS Category	HS Starting Age (Days)	HS Ending Age (Days)	HS Duration in a Day (Hours)	Peak Temperature
Ayazi, 2014 [32]	Ross 308	-	Iran	Chronic	1	42	24	32 ± 1 °C
Bai et al., 2019 [33]	Arbor Acres	50% each	China	Cyclic	22	35	8	34 °C
Dai et al., 2011 [34]	Arbor Acres	Male	China	Cyclic	22	42	9	34 °C
Hu et al., 2015a [21]	Arbor Acres	Male	China	Cyclic	22	42	9	34 °C
Hu et al., 2015b [22]	Arbor Acres	Male	China	Cyclic	22	35	9	35 °C
Jazideh et al., 2014 [35]	Ross 308	Male	Iran	Chronic	1	42	24	32 ± 1 °C
Sifa et al., 2018 [16]	Arbor Acres	-	China	Acute	42	42	24	34 ± 1 °C
Wu et al., 2018 [9]	Arbor Acres	50% each	China	Cyclic	22	41	10	33 ± 1 °C
Wu et al., 2020 [36]	Arbor Acres	-	China	Cyclic	21	42	10	36 ± 1 °C
Dai et al., 2009 [37]	Arbor Acres	Male	China	Chronic	35	42	24	28 °C
Hu et al., 2020a [23]	Arbor Acres	-	China	Cyclic	22	42	8	34 °C
Hu et al., 2020b [38]	Arbor Acres	50% each	China	Cyclic	22	42	8	35 °C
Hu et al., 2016 [39]	Arbor Acres	Male	China	Acute	35	35	12	34 ± 1 °C

The HS categories can be defined as followed: acute: HS challenge of short duration (usually no more than 24 h); chronic: HS challenge of prolonged duration without variation in the temperature; cyclic: HS challenge of prolonged duration alternating period of high ambient and thermoneutral temperatures. Abbreviation: HS: heat stress.