Table 4. Muscle fiber characteristics of bovine and porcine skeletal muscles

Muscles	Treats	Muscle fiber type¹⁾						SE
Muscles	Treats	I	IIA	IIA+IIX	IIX	IIX+IIB	IIB	SE
Bovine skeletal muscles
Psoas major	Cross-sectional area (μm²)	2,389^B	3,646^AB	4,205^A	4,806^A	-	-	295.21
	Relative area (%)	38.19^A	26.94^A	5.16^B	29.71^A	-	-	4.18
	Relative number (%)	51.85^A	23.92^B	3.96^C	20.28^B	-	-	5.74
Longissimus thoracis	Cross-sectional area (μm²)	2,706	2,247	2,796	2,756	-	-	44.54
	Relative area (%)	30.44^B	26.57^C	3.38^D	39.61^A	-	-	3.69
	Relative number (%)	29.08^B	30.63^B	3.12^C	37.16^A	-	-	3.72
Semimembranosus	Cross-sectional area (μm²)	3,016^B	4,095^A	4,212^A	4,064^A	-	-	219.92
	Relative area (%)	26.67^B	35.24^A	4.74^C	33.35^A	-	-	3.27
	Relative number (%)	33.11^A	32.11^A	4.16^B	30.61^A	-	-	3.51
Semitendinosus	Cross-sectional area (μm²)	3,137^C	3,889^B	4,365^AB	4,724^A	-	-	245.47
	Relative area (%)	25.13^B	26.05^B	1.97^C	46.86^A	-	-	4.61
	Relative number (%)	31.85^B	26.67^C	1.90^D	39.58^A	-	-	4.07
Porcine skeletal muscles
Psoas major	Cross-sectional area (μm²)	2,375^C	2,166^C	-	3,409^B	-	4,191^A	216.04
	Relative area (%)	18.47^C	20.38^BC	-	28.76^AB	-	32.38^A	2.18
	Relative number (%)	23.48	28.13	-	25.20	-	23.19	1.30
Longissimus thoracis	Cross-sectional area (μm²)	2,743^C	3,052^C	4,765^BC	6,869^AB	8,251^A	6,114^AB	438.73
	Relative area (%)	6.23^C	3.40^C	0.44^C	17.62^B	4.39^C	68.14^A	4.29
	Relative number (%)	12.85^B	6.12^C	0.57^D	14.55^B	3.06^CD	63.14^A	3.97
Semimembranosus	Cross-sectional area (μm²)	3,055^C	3,011^C	6,631^A	3,634^BC	4,520^B	6,997^A	359.70
	Relative area (%)	6.28^B	4.69^B	2.91^B	7.16^B	2.32^B	79.26^A	5.50
	Relative number (%)	11.95^B	8.59^BC	2.62^C	11.35^B	2.86^C	65.37^A	4.17
Semitendinosus	Cross-sectional area (μm²)	4,866^CD	4,468^D	4,992^CD	5,407^C	7,479^A	6,282^B	213.76
	Relative area (%)	23.89^A	14.07^B	1.59^C	24.78^A	5.97^BC	29.70^A	1.97
	Relative number (%)	26.66^A	17.03^A	1.67^B	24.67^A	4.32^B	25.65^A	2.01

Muscle fiber types were identified by monoclonal antibodies being specific to myosin heavy chains, as shown in Table 3.
Means±SE with different superscripts are significantly different within a same row (p<0.05).