The study investigated the effects of mulberry leaf extracts (MLE) on the color, lipid oxidation, antioxidant enzyme activities and oxidative breakdown products of raw ground beef during refrigerated storage. The five treatments were: MLE at 0, 100, 500 and 1,000 lg/g muscle (C, low concentration mulberry leaves extracts (LM), medium concentration mulberry leaves extracts (MM) and high concentration mulberry leaves extracts (HM)) and positive control with 20 lg Vitamin E/g muscle (VE). MLE maintained color, reduced peroxide and thiobarbituric acid reactive substances values during storage (P < 0.05) with no effect on free thiol. MLE increased activities of superoxide dismutase and glutathione peroxidase at 312 h (P < 0.05). There were more phospholipids from the HM treatment than the control group (P < 0.05); unsaturated fatty acids and reducing sugars in the VE group were higher than the C group (P < 0.05). The results indicated that MLE could better use as natural antioxidants to maintain the meat quality, extend shelf-life and prevent economic loss for food processing industry. In addition, one interesting finding was that the antioxidant mechanism of MLE was different comparing to VE during the different stages of lipid oxidation, which MLE worked at the first step and VE protected the second step when phospholipid was decomposed into unsaturated fatty acids. Therefore, we could conclude that it would be better to combine the MLE and VE to protect the meat quality during refrigerated storage. PRACTICAL APPLICATIONSMulberry leaves were rich in alkaloids, polyphenols, flavonoids and anthocyanins, which could be responsible for health benefits as well as herbal medicine for many years in various cultures. Some studies had found that MLE had the antioxidant activities. However, scientific information about the antioxidant properties of MLE in meat and their influence on meat quality is still scarce. The results indicate that MLE have the antioxidant activity, helping maintain the meat color, inhibiting lipid oxidant and enhancing antioxidant enzyme activity. In addition, the antioxidant mechanism of MLE protected phospholipids from oxidation and VE mainly protected the unsaturated fatty acids and reducing sugars. This research explains the antioxidant mechanism of MLE could better use as natural antioxidants to maintain the meat quality, extend shelf-life and prevent economic loss for food processing industry.

The objective of this study was to evaluate the effects of supplementation of phytoecdysteroids (PEDS) extracted from Cyanotis arachnoidea on rumen fermentation, enzymes activity and microbial efficiency in a dual flow continuous-culture system. A single-factor experimental design was used with twelve fermenters in 4 groups with 3 replicates each. Fermenters were incubated for a total of 7 days that included first 4 days for adaptation and last 3 days for sampling. PEDS was added at levels of zero (as control), 5, 10, and 15 mg/g of the substrate (DM). The results showed that increasing supplementation levels of PEDS resulted in incremental digestibility of dry matter (DMD) (quadratic, P = 0.001) and organic matter (OMD) (quadratic, P = 0.031), but unchanged digestibility of neutral detergent fiber (NDFD), crude protein (CPD) and acid detergent acid (ADFD). As supplementation levels of PEDS increased, there were decreased response in the concentration of ammonia nitrogen (NH3-N) (linear, P = 0.015) and increased response in molar proportions of butyrate (linear, P = 0.004), but unchanged response in total volatile fatty acid (TVFA) and the molar proportion of acetate and propionate, respectively. Increasing PEDS supplementation levels decreased the ratio of acetate to propionate (linear, P = 0.038), suggesting an alteration of rumen fermentation pattern occurring due to PEDS supplementation in the diet. Supplementation of PEDS significantly increased activities of glutamate dehydrogenase (quadratic, P = 0.001), alanine dehydrogenase (quadratic, P = 0.004), glutamate synthase (linear, P = 0.038), glutamine synthetase (quadratic, P = 0.011), respectively. There were no discernible differences in the activity of carboxymethyl cellulose (CMCase), xylanase and protease regardless of the treatments. The daily production of microbial nitrogen (linear, P = 0.002) and microbial efficiency (MOEEF) (linear, P = 0.001) increased linearly as supplementation levels of PEDS increased. The decreased response of fluid NH3-N and the increased response of MN indicated that PEDS positively increased the synthesis of microbial proteins.

We estimated ruminal crude protein degradation of twelve feedstuffs commonly used in China using in vitro and in vivo methods. The in vivo net protein utilization (NPU) levels of corn, sorghum, barley, wheat, Chinese wild rye grass, corn stalk, rice straw, soybean straw, soybean meal, distillers’ dried grains with solubles (DDGS), Brewers’ spent grains, and sunflower meal were 52.57, 49.68, 65.38, 72.58, 82.41, 72.26, 68.57, 76.95, 54.75, 56.27, 29.03 and 41.88%, respectively. The linear regression between NH 3 -N incorporated into microbial proteins and gas production after incubation (6, 12, and 24 h) was significant (r = 0.9948 and P < 0.001, r = 0.9874 and P < 0.01, and r = 0.9912 and P < 0.01, respectively). Based on the linear regression equations, we estimated in vitro protein degradability (IVPD) and generated the regression equations between IVPD and NPU. The linear regression equations between IVPD and NPU after 6 h incubation in the energy, protein, and roughage feed groups were Y = 0.5633X + 33.20 (R 2 = 0.8517, P < 0.05), Y = 0.8482X+ 34.81 (R 2 = 0.8650, P < 0.05), and Y = 1.6295X − 17.70 (R 2 = 0.909, P < 0.05), respectively. The in vitro gas production method is useful for the determination of protein degradation in feedstuffs.