ABSTRACT: succinate (SUC), as a feed additive, can regulate muscle fiber structure and fat deposition, and has a positive effect on meat quality. In this study, 30 male Tan sheep lambs were selected to investigate the effects of SUC in diet on Tan sheep production performance, lamb quality, muscle fiber structure, liver and longissimus' muscle entities (LT) transcriptomes. Different levels of SUC were fed (0%, 1.0%, 2.0%, respectively) and the experiment lasted for 60 days. Compared with CON group, 2% SUC group significantly increased average daily gain from 1 to 15 days and 46 to 60 days during the experiment period, and significantly increased dry matter intake from 1 to 15 days, 16 to 30 days and 46 to 60 days during the experiment period (P<0.05). Both 1% SUC group and 2% SUC group could decrease feed to gain ratio and increase carcass weight (P<0.05). The slaughter rate of 2% SUC group was significantly increased (P=0.012). In both 1% SUC and 2% SUC groups, shear force and cooking loss were decreased, intramuscular fat was increased, and a* of LT muscle was increased (P=0.036). In addition, the muscle fiber structure of Tan sheep LT muscle in 1% SUC group and 2% SUC group was changed, the diameter of muscle fiber was decreased, the cross-sectional area of type Ⅰ and type Ⅱa muscle fiber was decreased, and the density of type Ⅰ muscle fiber was increased (P<0.05). Transcriptomic results showed that the addition of SUC can change the expression of muscle development and muscle fiber type transformation genes. Differential genes are mainly involved in various pathways related to lipid metabolism, energy metabolism and muscle development, improve muscle glucose uptake capacity, and improve meat quality in circadian rhythm. In conclusion, SUC can regulate the nutritional metabolism of Tan Sheep, change the muscle fiber structure of Tan Sheep, and improve the production performance and meat quality. Our results show that adding 1% SUC to the Tan sheep diet is productively more beneficial.
