Table 5.

Myofiber characteristics in the Semitendinosus muscle of selected offspring born from oviduct ligated (OL; non crowded) and intact (IN; relatively crowded) sows fed an unsupplemented (Ctrl) or l-arginine supplemented diet (ARG) from d 14 to 28 of gestation¹

	IN		OL				P-value2
Item	Ctrl	ARG	Ctrl	ARG	SEM	IUC	DIET	BtW	IUC×DIET	DIET×BtW
Observations	19	19	17	15
Muscle area, μm2 × 107
Total	5.762	6.780	7.505	8.795	0.9429	0.144	0.003	0.653	0.738	0.053
Dark portion	2.359x	2.278x	2.772ax	3.572by	0.2931	0.078	0.025	0.233	0.007	0.573
Light portion	3.151	4.118	4.906	5.677	0.8279	0.143	0.011	0.910	0.786	0.061
Myofiber number, N
Total muscle	476,025	527,711	536,451	607,928	35,511.0	0.236	0.003	0.136	0.604	0.475
Dark portion
Total myofibers	193,928	198,254	184,590	218,604	22,898.2	0.884	0.131	0.002	0.231	0.560
Primary myofibers (P)	6,105	5,840	5,868	6,156	638.8	0.970	0.974	0.069	0.422	0.575
Secondary myofibers (S)	187,823	192,414	178,722	212,448	22,455.9	0.883	0.124	0.002	0.231	0.559
S:P ratio3	30.8	33.2	30.6	34.4	2.86	0.912	0.051	0.356	0.643	0.337
Light portion	282,097	329,457	351,860	389,324	32,639.6	0.234	0.022	0.889	0.778	0.236

¹Results are presented as least squares means of interactions between the two main factors extent of intra uterine crowding and dietary treatment and pooled SEM

²Probability values for the effects of extent of intra uterine crowding (IUC), dietary treatment (DIET), birth weight (BtW), and interactions IUC × DIET and DIET × BtW

³The secondary-to-primary myofiber ratio, calculated by dividing the number of secondary with the number of primary myofibers in the dark portion of the Semitendinosus muscle.

^a,bWithin a row for the main factor treatment, least squares means without a common superscript differ (P < 0.05)

^x,yWithin a row for the main factor treatment, least squares means without a common superscript differ (0.05 < P < 0.10)