Table 5.

Effects of constant chronic heat stress on villus height and crypt depth of small intestine segments in growing-finishing pigs

Items	Treatments			P-value
	TN	HS	PF
Duodenum
Villus height, μm	574.50 ± 25.54a	379.49 ± 36.00b	414.50 ± 25.26b	< 0.001
Crypt depth, μm	505.42 ± 17.15	449.10 ± 38.36	396.94 ± 41.88	0.115
Ratio of villus height to crypt depth	1.14 ± 0.02a	0.84 ± 0.03b	1.07 ± 0.05a	< 0.001
Jejunum
Villus height, μm	510.37 ± 39.01a	319.29 ± 28.62b	384.90 ± 11.37b	< 0.001
Crypt depth, μm	292.53 ± 9.28a	218.69 ± 26.00b	218.78 ± 17.76b	0.021
Ratio of villus height to crypt depth	1.73 ± 0.08a	1.49 ± 0.07b	1.80 ± 0.09a	0.042
Ileum
Villus height, μm	526.36 ± 25.43a	298.98 ± 28.33b	367.27 ± 25.96b	< 0.001
Crypt depth, μm	403.73 ± 23.42	367.29 ± 35.48	328.54 ± 30.47	0.244
Ratio of villus height to crypt depth	1.31 ± 0.03a	0.82 ± 0.04c	1.14 ± 0.06b	< 0.001

TN, thermal neutral conditions (25 ± 1 °C); HS, heat stress conditions (35 ± 1 °C); PF, pair-fed with HS with TN conditions (25 ± 1 °C). Data were expressed as mean ± SEM (n = 8 for TN and PF, n = 7 for HS). Treatments with different superscript letters were significantly different at P < 0.05