Table 4 Gut histological morphometrics of salmon parr fed four different experimental diets for 12 weeks (FM, PL, PHP and SPH diets). Values with different superscripts in the same row are significantly different (*nested or ^† one-way ANOVA; p < 0.05, n=3, ± SD).

Villi height (μm)*

473.67 ± 130.92

448.30 ± 227.62

435.12 ± 159.02

514.30 ± 161.04

Villi width (μm) ^†

76.31 ± 14.92^a

76.44 ± 22.63^a

75.09 ± 14.89^a

91.67 ± 20.33^b

Vh/Vw ratio ^†

6.37 ± 1.97

6.21 ± 3.35

5.83 ± 1.80

5.68 ± 1.60

Intestinal wall width (μm) ^†

58.97 ± 20.18^a

63.18 ± 29.97^a

65.57 ± 23.16^a

84.93 ± 23.62^b

Intestine diameter (mm)*

2.23 ± 0.56

2.10 ± 0.84

2.08 ± 0.50

2.43 ± 0.54

Interior lumen area (mm²)*

1.90 ± 1.18

1.63 ± 1.30

1.46 ± 0.68

1.68 ± 0.71

Internal perimeter (mm)*

24.73 ± 10.35

21.13 ± 9.46

25.16 ± 9.29

27.15 ± 7.42

External perimeter (mm)*

7.35 ± 1.88

6.59 ± 2.47

6.51 ± 1.50

7.48 ± 1.50

Perimeter ratio (abs) *

3.34 ± 0.81

3.24 ± 0.88

3.77 ± 0.62

3.62 ± 0.55