Table 5. Effect of feed-grade methionine isomers in diet and heat stress on gut morphology of broilers¹.

Item	Acute heat stress		Thermo-neutral control		SEM2	P value
	L-Methionine	D-Methionine	L-Methionine	D-Methionine		HS3	Diet4	HS×Diet
Day 14
Villous height	499.60	327.58	505.28	465.16	19.42	0.102	0.026	0.128
Crypt depth	62.47	69.27	66.02	70.49	4.42	0.794	0.542	0.899
V:C5	8.38	4.74	7.79	7.03	0.52	0.431	0.065	0.199
Day 21
Villous height	502.937	377.58	571.95	565.16	12.25	0.003	0.062	0.088
Crypt depth	71.46	77.37	63.69	66.35	1.72	0.026	0.247	0.649
V:C	7.037	4.97	8.983	8.55	0.29	0.001	0.062	0.194
Day 35
Villous height	902.51	847.64	977.53	945.86	64.24	0.519	0.745	0.930
Crypt depth	111.53	113.03	116.20	119.82	2.117	0.213	0.562	0.808
V:C	8.03	7.50	8.41	7.74	0.447	0.736	0.520	0.941

¹Values are the mean of six (10 measurements each) replicates per treatment.

²Pooled standard error of mean

³Heat stress condition (acute heat stress vs. thermo-neutral control)

⁴Dietary methionine isomers

⁵Villous height: Crypt depth ratio