Hailing Luo

Antioxidant effects of liquorice (Glycyrrhiza uralensis) extract during aging of longissimus thoracis muscle in Tan sheep

The study was conducted to investigate the potential of liquorice extract (LE) from Glycyrrhiza uralensis as a dietary supplement for sheep to improve antioxidant capacity of meat. Fifty Tan sheep were randomly allocated to five groups with LE supplementation at levels of 0, 1000, 2000, 3000 and 4000 mg/kg feed. After 120 days, the longissimus thoracis muscle was sampled and conditioned for 0, 2, 4, 6 and 8 days at 4 °C. The results revealed that LE scavenged free radical in a dose-response manner in vitro. Supplementation with LE in animal diet increased (P<0.05) antioxidant content and radical scavenging activity while it decreased (P<0.05) reactive oxygen species (ROS) and thiobarbituric acid reactive substance (TBARS) levels of meat. Dietary LE supplementation can improve antioxidant capacity of meat, and the optimum dosage range of LE supplementation appeared to be 3000 to 4000 mg/kg feed.

Effect of Restricted Grazing Time on the Foraging Behavior and Movement of Tan Sheep Grazed on Desert Steppe

To investigate the effect of restricted grazing time on behavior of Tan sheep on desert steppe, forty 4-months old male Tan sheep with an original body weight (BW) of 15.62±0.33 kg were randomly allocated to 4 grazing groups which corresponded to 4 different restricted grazing time treatments of 2 h/d (G2), 4 h/d (G4), 8 h/d (G8) and 12 h/d (G12) access to pasture. The restricted grazing times had a significant impact on intake time, resting time, ruminating time, bite rate and movement. As the grazing time decreased, the proportion of time spent on intake, bite rate and grazing velocity significantly (p<0.05) increased, but resting and ruminating time clearly (p<0.05) decreased. The grazing months mainly depicted effect on intake time and grazing velocity. In conclusion, by varying their foraging behavior, Tan sheep could improve grazing efficiency to adapt well to the time-limited grazing circumstance.

Effects of Dietary Lycopene Supplementation on Plasma Lipid Profile, Lipid Peroxidation and Antioxidant Defense System in Feedlot Bamei Lamb

Lycopene, a red non-provitamin A carotenoid, mainly presenting in tomato and tomato byproducts, has the highest antioxidant activity among carotenoids because of its high number of conjugated double bonds. The objective of this study was to investigate the effect of lycopene supplementation in the diet on plasma lipid profile, lipid peroxidation and antioxidant defense system in feedlot lamb. Twenty-eight Bamei male lambs (90 days old) were divided into four groups and fed a basal diet (LP0, 40:60 roughage: concentrate) or the basal diet supplemented with 50, 100, and 200 mg/kg lycopene. After 120 days of feeding, all lambs were slaughtered and sampled. Dietary lycopene supplementation significantly reduced the levels of plasma total cholesterol (p<0.05, linearly), total triglycerides (TG, p<0.05) and low-density lipoprotein cholesterol (LDL-C, p<0.05), as well as atherogenic index (p<0.001), whereas no change was observed in high-density lipoprotein cholesterol (p>0.05). The levels of TG (p<0.001) and LDL-C (p<0.001) were decreased with the feeding time extension, and both showed a linear trend (p<0.01). Malondialdehyde level in plasma and liver decreased linearly with the increase of lycopene inclusion levels (p<0.01). Dietary lycopene intake linearly increased the plasma antioxidant vitamin E level (p<0.001), total antioxidant capacity (T-AOC, p<0.05), and activities of catalase (CAT, p<0.01), glutathione peroxidase (GSH-Px, p<0.05) and superoxide dismutase (SOD, p<0.05). The plasma T-AOC and activities of GSH-Px and SOD decreased with the extension of the feeding time. In liver, dietary lycopene inclusion showed similar antioxidant effects with respect to activities of CAT (p<0.05, linearly) and SOD (p<0.001, linearly). Therefore, it was concluded that lycopene supplementation improved the antioxidant status of the lamb and optimized the plasma lipid profile, the dosage of 200 mg lycopene/kg feed might be desirable for growing lambs to prevent environment stress and maintain normal physiological metabolism.

Regulation of sheep α-TTP by dietary vitamin E and preparation of monoclonal antibody for sheep α-TTP.

α-Tocopherol transfer protein (α-TTP) is a cytosolic protein that plays an important role in regulating concentrations of plasma α-tocopherol (the most bio-active form of vitamin E). Despite the central roles that α-TTP plays in maintaining vitamin E adequacy, we have only recently proved the existence of the α-TTP gene in sheep and, for the first time, cloned its full-length cDNA. However, the study of sheep α-TTP is still in its infancy. In the present study, thirty-five local male lambs of Tan sheep with similar initial body weight were randomly divided into five groups and fed with diets supplemented with 0 (control group), 20, 100, 200, 2000IU·sheep(-1)·d(-1) vitamin E for 120 days. At the end of the experiment, the plasma and liver vitamin E contents were analyzed first and then α-TTP mRNA and protein expression levels were determined by quantitative real-time PCR (qRT-PCR) and Western-blot analysis, respectively. In addition, as no sheep α-TTP antibody was available, a specific monoclonal antibody (McAb) against the ovine α-TTP protein was prepared. The effect of vitamin E supplementation was confirmed by the significant changes in the concentrations of vitamin E in the plasma and liver. As shown by qRT-PCR and Western-blot analysis, dietary vitamin E does not affect sheep α-TTP gene expression, except for high levels of vitamin E supplementation, which significantly increased expression at the protein level. Importantly, the specific sheep anti-α-TTP McAb we generated could provide optimal recognition in ELISA, Western-blot and immunohistochemistry assays, which will be a powerful tool in future studies of the biological functions of sheep α-TTP.

Dietary vitamin E affects α-TTP mRNA levels in different tissues of the Tan sheep

The α-tocopherol transfer protein (α-TTP) is a ~32kDa cytosolic protein that plays an important role in the efficient circulation of plasma α-tocopherol in the body, a factor with great relevance in reproduction. The α-TTP gene has been studied in a number of tissues; however, its expression and function in some ovine tissues remain unclear. A previous study from our laboratory has demonstrated α-TTP expression in sheep liver. In the present study we determined whether α-TTP is expressed in non-liver tissues and investigated the effects of dietary vitamin E on the α-TTP mRNA levels. Thirty-five male Tan sheep with similar body weight were randomly allocated into five groups and supplemented 0, 20, 100, 200 and 2000IUsheep(-1)day(-1) vitamin E, for four months, respectively. At the end of the study, the animals were slaughtered and tissue samples from the heart, spleen, lung, kidney, longissimus dorsi muscle and gluteus muscle were immediately collected. We found that the α-TTP gene is expressed in sheep tissues other than the liver. Moreover, dietary vitamin E levels had influenced the expression levels of α-TTP gene in these tissues in a tissue-specific way. The technique of immunohistochemistry was used to detect α-TTP in tissues of the heart, spleen, lung, and kidney and we found that α-TTP was mainly located in the cytoplasm while no α-TTP immunoreactivity was detected in the cytoplasm of longissimus dorsi and gluteus muscle samples. Importantly, our findings lay the foundation for additional experiments focusing on the absorption and metabolism of vitamin E in tissues other than the liver.

Screening of α-Tocopherol Transfer Protein Sensitive Genes in Human Hepatoma Cells (HepG2).

α-Tocopherol transfer protein (α-TTP) is a ~32 kDa protein expressed mainly in hepatocytes. The major function of the protein is to bind specifically to α-tocopherol and, together, the complex transfers from late lysosomes to the cell membrane. A previous study indicated that some factors might be required in the transferring process. However, there is little information available about the potential transferring factors. In addition, there remains much to learn about other physiological processes which α-TTP might participate in. Thus, in this study a human α-TTP eukaryotic expression vector was successfully constructed and expressed in human hepatoma cells (HepG2). The sensitive genes related to α-TTP were then screened by microarray technology. Results showed that expression of the vector in HepG2 cells led to the identification of 323 genes showing differential expression. The differentially expressed transcripts were divided into four main categories, including (1) cell inflammation; (2) cell cycle and cell apoptosis; (3) cell signaling and gene regulation; and (4) cellular movement. A few cellular movement related transcripts were selected and verified by quantitative real-time PCR. Expressions of some were significantly increased in α-TTP-expressed group, which indicated that these factors were likely to play a role in the transferring process.

Influence of Restricted Grazing Time Systems on Productive Performance and Fatty Acid Composition of Longissimus dorsi in Growing Lambs

Fifty 3-month-old male Tan lambs (similar in body weight) were divided into 5 groups to investigate the effects of different restricted pasture grazing times and indoor supplementation on the productive performances and fatty acid composition of the intramuscular fat in growing lambs. The lambs grazed for different periods of time (12 h/d, 8 h/d, 4 h/d, 2 h/d, and 0 h) and received various amounts of supplementary feedings during the 120-day trial. Pasture dry matter intake (DMI), total DMI, average daily gains and the live body weights of the lambs were measured during the experiment. The animals were slaughtered at the end of the study, their carcass traits were measured, and their longissimus dorsi muscles were sampled to analyze the intramuscular fat (IMF) content and fatty acid profiles. The results indicated that the different durations of grazing and supplementary feedings affected the animal performances and the composition of fatty acids. Grazing for 8 h/d or 2 h/d with the corresponding supplementary concentrate resulted in lambs with higher body weights, carcass weights and IMF contents. Lambs with longer grazing times and less concentrate accumulated more healthy fatty acids such as conjugated linoleic acid and n-3 polyunsaturated fatty acid and had higher n-3/n-6 ratios. Overall, a grazing allowance of 8 h/d and the corresponding concentrate was recommended to maintain a high quantity and quality of lamb meat.

Transcriptome analysis of the Tan sheep testes: Differential expression of antioxidant enzyme-related genes and proteins in response to dietary vitamin E supplementation.

Gene-chip technology was employed to study the effect of dietary vitamin E on gene expression in sheep testes based on our previous research. Thirty-five male Tan sheep (20-30 days after weaning) with similar body weight were randomly allocated into five groups and supplemented 0, 20, 100, 200 and 2,000 IU sheep(-1)day(-1) vitamin E (treatments denoted as E0, E20, E100, E200, and E2000, respectively) for 120 days. At the end of the study the sheep were slaughtered and the testis samples were immediately collected and stored in liquid nitrogen. Differences in gene expression between different treated groups were identified. Based on GO enrichment analysis and the KEGG database to evaluate the gene expression data we found that vitamin E might affect genes in the testes by modulating the oxidation level, by affecting the expression of various receptors and transcription factors in biological pathways, and by regulating the expression of metabolism-associated genes. The effect of vitamin E supplementation on the expression of oxidative enzyme-related genes was detected by quantitative real-time PCR (qRT-PCR) and Western blot. The results show that dietary vitamin E, at various doses, can significantly increase (P<0.05) the mRNA and protein expression of Glutathione peroxidase 3 and Glutathione S-transferase alpha 1. In addition, the results of qRT-PCR of the antioxidant enzyme genes were consistent with those obtained using the gene chip microarray analysis. In summary, the dietary vitamin E treatment altered the expression of a number of genes in sheep testes. The increase in the mRNA and protein levels of antioxidant enzyme genes, coupled with the elevation in the activity of the antioxidant enzymes were primarily responsible for the improved reproductive performance promoted by dietary vitamin E.

Dietary lycopene powder improves meat oxidative stability in Hu lambs: Effect of dietary lycopene powder on lamb meat quality

BACKGROUND The aim of this study was to evaluate the effect of dietary lycopene powder on meat quality and the oxidative stability of lipid and protein of longissimus thoracis (LT) in lamb. A total of 30 male lambs were randomly sampled from three feeding groups (control without lycopene supplement, 200 and 400 mg kg-1 lycopene powder respectively) after 3 months of feeding. The muscle samples were taken after slaughter and stored at 4 °C for 7 days. RESULTS Compared with the control, the results showed that supplementation with lycopene powder gave a higher a* value (redness), and increased the levels of vitamin A and vitamin E. Increasing dietary lycopene powder resulted in a lower degree of lipid and protein oxidation, as evidenced by lower contents of thiobarbituric acid-reactive substance and carbonyl compounds, and higher levels of sulfhydryl groups. CONCLUSION Dietary lycopene powder is an effective antioxidant that blocks the oxidation of meat proteins and lipids, and has a positive effect on increasing lamb meat quality during storage.