Table 1. Effect of heat stress on microbial diversity and microbiota composition at the predominant phylum level in the gut of livestock

Reference Animal Thermoneutral vs. HS Site Alpha-diversity Beta-diversity1)
Chao1 Shannon Firmicutes Bacteroidetes Proteobacteria Other phyla
[22] Broiler chickens 22°C vs. 32°C for 14 days Cecum 428 vs. 440 5.48 vs. 5.46 ↑ by 14% = =
[28] Broiler chickens 24°C–26°C vs. 34°C–38°C for 28 days Cecum (day 3) - - 57.7 vs. 55.9 37.0 vs. 39.4 4.97 vs. 3.62 =
Cecum (day 7) - - 58.5 vs. 68.5↑ 33.2 vs. 22.5↓ 7.29 vs. 6.76 Tenericutes: 1.0 vs. 0.74↓
Cecum (day 14) - - 62.5 vs. 71.7↑ 32.8 vs. 23.6↓ 3.01 vs. 4.03↑ Cyanobacteria: 0.52 vs. 0.13↓
Cecum (day 28) - - 68.6 vs. 69.3 26.2 vs. 26.7 3.43 vs. 2.22 =
[36] Cows (high HS sensitivity) THI of 65.5 vs. 80.2 Feces - -. = = =
Cows (low HS sensitivity) THI of 65.5 vs. 80.2 Feces - - = = =
[19] Broiler chickens 21°C vs. 31°C from 28 to 42 days Ileum 95.5 vs. 176↑ 1.90 vs. 2.27 85.6 vs. 92.2↑ 5.07 vs. 2.58↓ 7.39 vs. 1.93↓ =
[21] Hens 21°C vs. 29°C–35°C for 28 days Cecum = - 18.7 vs. 17.4 49.9 vs. 54.8 = =
[31] Laying hens 25°C vs. 35°C for 24 h Feces - - 54.7% vs. 45.9% ↓ 26.1% vs. 43.1%↑ 6.57% vs. 3.70% ↓ Fusobacteria
[23] Cherry-valley ducks 25°C vs. 32°C for 8 h/day for 21 days Jejunum - = 45.4 vs. 12.0 ↓ = 39.0 vs.72.7↑ =
Ileum - = = = = =
Cecum = = = = =
[24] Sows 18°C–22°C vs. 28°C–32°C for 30 days Feces 754 vs. 797 4.85 vs. 4.95 = = = Spirochaeta↓ (tended)
[20] Pigs 25°C vs. 29°C for 21 days Feces - = 66.9 vs. 70.8↑ 24.9 vs. 17.6↓ 0.79 vs. 0.77 Spirochaetes: 1.4 vs. 2.11↑
Fibrobacteres: 0.25 vs. 0.40↑
Tenericutes: 0.01 vs. 0.03↑
[25] Pigs 25°C vs. 35°C for 24 h Feces - = = =
[27] 15°C vs. 35°C for 6 days Rumen = = = = Planctomycetes↓, Chloroflexi↓
Relative abundances (%) are presented depending upon the availability of the information in the literature.
The symbols ‘↓’ or ‘↑’ indicate that abundances of microbiota at phylum level decreased (p < 0.05) or increased (p < 0.05) in the heat stress conditions compared with the control thermoneutral conditions.
The symbol ‘=’ indicates that abundances of microbiota at phylum level in the heat stress conditions was similar (p > 0.10) to control thermoneutral conditions.
HS, heat stress; THI, temperature humidity index.