Table 4. Effect of dietary supplementation of the different proteases on the intestinal morphology of broilers in each experimental group at 32 days of age

	PC	NC	PR1	PR2	PR3	SEM	p-value
Duodenum
Villus height	226.37^cd	223.61^d	280.05^ab	259.88^bc	299.56^a	7.8988	< 0.0001
Villus width	32.02^a	25.55^b	26.24^b	26.31^b	32.22^a	1.1154	< 0.0001
Crypt depth	26.74^b	25.44^b	29.18^b	28.94^b	36.86^a	1.1979	< 0.0001
VH:CD	9.01^b	9.06^ab	9.75^ab	10.66^a	9.01^b	0.4230	0.0173
Jejunum
Villus height	187.83^bc	163.84^c	200.13^b	191.17^bc	230.68^a	7.5963	< 0.0001
Villus width	35.26^a	27.33^b	28.25^ab	28.87^ab	28.64^ab	1.8999	0.0603
Crypt depth	22.52^b	23.68^b	25.39^b	21.76^b	35.11^a	0.9437	< 0.0001
VH:CD	8.74^a	7.34^bc	8.50^ab	9.28^a	6.62^c	0.3570	< 0.0001
Ileum
Villus height	182.40^a	147.53^b	160.28^ab	158.52^ab	162.56^ab	6.0764	0.0059
Villus width	38.32^a	35.50^ab	30.81^bc	28.58^c	31.79^abc	1.5900	0.0004
Crypt depth	21.11^b	25.92^ab	22.88^b	22.63^b	31.48^a	1.5513	< 0.0001
VH:CD	9.47^a	5.82^c	7.16^bc	7.52^b	6.22^bc	0.3800	< 0.0001

Values with different superscripts in the same row were significantly different (p < 0.05).
PC, positive control diet formulated to meet Ross 308 AA requirements; NC, negative control diet reformulated to 3.5% lower AA compared PC; PR1, NC supplemented with 3,000 U/kg (300 mg/kg) of a multi-protease solution, containing 3 different coated proteases produced from Aspergillus niger, Bacillus subtilis and Bacillus licheniformis; PR2, NC supplemented with 15,000 U/kg (200 mg/kg) of a serine protease produced from Bacillus licheniformis; PR3, NC supplemented with 30,000 U/kg (500 mg/kg) of an alkaline protease produced from Bacillus licheniformis. SEM, n = 10 replicates per treatment (1 male bird per replicate). VH:CD, villus height to crypt depth ratio.