Figure 1.
Figure 1.

Warner–Bratzler shear force (WBSF) in semitendinosus (ST) muscle of ad libitum (□) and feed restriction (■) ram lambs. Semitendinosus muscle was sampled, aging for 14 d, and cooked at 177°C. Warner–Bratzler shear force was measured by a shear force instrument (Mecmesin, West Sussex, UK). Data showed that WBSF in ST muscle was increased by feed restriction. *P < 0.05. (Mean ± SEM; n = 6 in each group.)

 


Figure 2.
Figure 2.

Collagen deposition in semitendinosus (ST) muscle of ad libitum (□) and feed restriction (■) ram lambs. (A and B) Trichrome staining analysis showed that more collagen was deposited in ST muscle when animal were fed with restricted feed. (C) Hydroxyproline determination assay further confirmed the increased collagen contents in feed restricted ST muscle. (D) Real-time PCR indicated that both collagen I and fibronectin mRNA contents were increased by feed restriction, whereas no change was observed for collagen III. **P < 0.01; *P < 0.05. (Mean ± SEM; n = 6 in each group.)

 


Figure 3.
Figure 3.

Muscle fiber area, size distribution, and intramuscular fat (IMF) content in semitendinosus muscle of ad libitum (□) and feed restriction (■) ram lambs. Data showed that muscle fiber area was reduced by feed restriction (A and B), whereas no change of IMF contents between 2 groups were observed (C).

 


Figure 4.
Figure 4.

Messenger RNA expression of lysyl oxidase (LO), lysyl hydroxylase 2b (LH2b), and prolyl 4-hydroxylase α (P4HA) in semitendinosus muscle of ad libitum (□) and feed restriction (■) ram lambs. Data showed that mRNA content of P4HA was increased by feed restriction, whereas no changes were observed for LO and LH2b mRNA expression. **P < 0.01. (Mean ± SEM; n = 6 in each group.)

 


Figure 5.
Figure 5.

mRNA expression of matrix metalloproteinases (MMP) and inhibitor of metalloproteinases (TIMP) in semitendinosus muscle of ad libitum (□) and feed restriction (■) ram lambs. Data showed that mRNA expression of MMP1, MMP2, MMP9, and MMP13 did not change (A). Messenger RNA expression of both TIMP2 and TIMP2 were increased, whereas no difference for the TIMP3 was observed (B). *P < 0.05. (Mean ± SEM; n = 6 in each group.)

 


Figure 6.
Figure 6.

The transforming growth factor β (TGF-β) signaling pathway, p38, and phosphros-p38 in semitendinosus muscle of ad libitum (□) and feed restriction (■) ram lambs. Western blotting data showed that there was no difference in TGF-β, Smad2/3, and phosphros-Smad2/3 protein contents (A, B, and C). An increased p38 phosphorylation was observed in feed restricted lambs (D and E). β-Actin was used as internal control; *P < 0.05. (Mean ± SEM; n = 6 in each group.)