Effects of a partial substitution of corn with wheat on the distribution of muscle fiber types and meat quality traits in plateau-type Tibetan sheep

In this study, we sought to determine the effects of substituting 10% of dietary maize with wheat flour on muscle fiber types, fatty acid contents, and antioxidant properties in plateau-type Tibetan sheep (Ovis aries). Sixty 2～3^th-old plateau Tibetan lambs with similar initial body weight (19.35 ± 2.18) kg and good development were randomly divided into one of two groups (with 5 repetitions per group), namely, a corn group (CG: fed pure corn as a concentrate) and a wheat group (WG: 10% of the corn concentrate substituted with wheat). The results revealed that compared with the CG group lambs, there were significantly fewer type Ⅰ muscle fibers in the WG group lambs (P < 0.01), whereas the number of type Ⅱ muscle fibers showed the opposite trend (P < 0.01). In addition, the relative mRNA expression of the MyHCI gene in WG group lambs was significantly higher than that in the CG group lambs (P < 0.01), whereas the relative expression of the MyHC IIb gene. The relative expression of docosanoic acid (C22:0) in CG group lambs was significantly higher than that in the WG group lambs (P < 0.05), whereas the relative expression of docosatrienoic acid (C22:3) in the CG group was significantly lower than that in the WG group (P < 0.05). Moreover, the two groups were found to show opposite trends with respect to total antioxidant capacity, malondialdehyde content, and glutathione peroxidase activity (P < 0.01). However, we detected no significant difference between the two groups with respect to the activities of the enzymes catalase and superoxide dismutase (P > 0.05). The findings of this study indicate that replacing 10% of dietary corn with wheat contributes to a certain improvement in the quality of plateau Tibetan sheep meat.