Effects of dietary daidzein supplementation on growth performance, carcass characteristics, and meat quality in growing-finishing pigs

This study was conducted to investigate the effect of dietary daidzein (DAI) supplementation on growth performance, carcass traits, and meat quality in growing-finishing pigs. Seventy-two DLY (Duroc x Landrace x Yorkshire) male castrated growing-pigs were randomly assigned to four treatments, and fed with a basal diet (CON) or basal diet containing different doses of DAI (12.5, 37.5, and 62.5 mg/kg). Results showed that DAI supplementation significantly increased (P < 0.05) the average daily gain (ADG). Moreover, DAI not only elevated the serum insulin-like growth factors-1 (IGF-1) and testosterone concentrations (P < 0.05), but also elevated the superoxide dismutase (SOD) activity and total antioxidant capacity (T-AOC). Interestingly, DAI supplementation at high dose (62.5 mg/kg) significantly increased the intramuscular fat (IMF) content but reduced the fat content in liver (P < 0.05). The drip loss and shear force were both decreased in pigs treated with 62.5 mg/kg DAI (P < 0.05). DAI supplementation elevated the expression level of MyHC I and decreased the expression level of MyHC IIb in longissimus thoracis (P < 0.05). Importantly, DAI altered the expression profiles of critical metabolic genes in the longissimus thoracis and liver. The phosphoenolpyruvate carboxykinase (PEPCK) and hormone-sensitive lipase (HSL) genes were downregulated in the longissimus thoracis (P < 0.05). However, the expression levels of fatty acid synthase (FASN) and acetyl CoA carboxylase 1 (ACC1) genes were upregulated by DAI (P < 0.05). In the liver, DAI elevated the expression level of glucokinase (GCK) but decreased the expression level of ACC1 (P < 0.05). These results not only indicate a beneficial effect of dietary DAI supplementation on growth performance but also offer potential mechanisms behind the DAI-regulated meat quality in pigs.