Keying Zhang

Sichuan Agricultural University, Hua-yang, Sichuan, China

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Publications (22)49.63 Total impact

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    ABSTRACT: The present study was conducted to determine whether dietary threonine supplementation can improve immunity of weaned pigs challenged by swine Pseudorabies live vaccine (SPLV). Thirty crossbred piglets weaned at 21 days of age were randomly assigned to three groups receiving diets containing true ileal digestible threonine (TIDT) at 0.74, 0.89 and 1.11% for 14 days. On day 8, all pigs were injected intramuscularly with SPLV or sterile 0.9% NaCl solution. SPLV injection enhanced serum IgA, IgM, IgG, IFN-γ, IL-1β, TNF-α and IL-10 concentrations (p < 0.05) and stimulated the relative mRNA abundance of Toll-like receptors (TLR3, TLR7 or TLR9) in different tissues (p < 0.05). Under no challenge, increasing dietary TIDT levels enhanced serum IgG (p < 0.05), IgM (p = 0.07) and IFN-γ (p < 0.05) concentration, tended to decrease serum IL-1β, TNF-α and IL-10 concentration, and regulated relative mRNA abundance of TLR3, TLR7 or TLR9 in different tissues (p < 0.05). However, there was a synergistic role for increasing the serum IL-10 concentration between dietary TIDT levels and SPLV injection (p < 0.05). Under SPLV challenge, increasing dietary TIDT levels attenuated the increase of the serum IFN-γ concentration, and the increase of the relative mRNA abundance of TLR3, TLR7 and TLR9 in the different tissues (p < 0.05). These results suggest that an appropriate dietary threonine supplementation could improve the immune status of weaned pigs injected with SPLV by down-regulating the expression of TLR3, TLR7 and TLR9 in tissues, and thus regulating T-helper cytokine secretion.
    Archives of Animal Nutrition 01/2014; · 1.10 Impact Factor
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    ABSTRACT: Mastitis endangers the health of domestic animals and humans, and may cause problems concerning food safety. It is documented that n-3 polyunsaturated fatty acids (PUFA) play significant roles in attenuating saturated fatty acids (SFA)-induced inflammation. This study was therefore conducted to determine whether mammary inflammation could be affected by consumption of diets rich in n-3 PUFA. Forty-eight rats after mating began to receive diets supplemented with 5% fish oil (FO) or 7% soybean oil (SO). Blood and mammary tissue samples (n = 6) at day 0 and 14 of gestation and day 3 postpartum were collected 9 hours after intramammary infusion of saline or lipopolysaccharide (LPS) to determine free fatty acids (FFA) concentration and FA composition in plasma and inflammation mediators in mammary tissues. At day 14 of gestation and day 3 postpartum, the FO-fed rats had lower plasma concentrations of C18:2n6, C20:4n6, total n-6 PUFA and SFA, and had higher plasma concentrations of C20:5n3 and total n-3 PUFA than the SO-fed rats. Plasma C22:6n3 concentration was also higher in the FO-fed than in the SO-fed rats at day 3 postpartum. Compared with the SO-fed rats, the FO-fed rats had lower mammary mRNA abundance of xanthine oxidoreductase (XOR) and protein level of tumor necrosis factor (TNF)-alpha, but had higher mammary mRNA abundances of interleukin (IL)-10 and peroxisome proliferator-activated receptor (PPAR)-gamma at day 14 of gestation. Following LPS infusion at day 3 postpartum, the SO-fed rats had increased plasma concentrations of FFA, C18:1n9, C18:3n3, C18:2n6 and total n-6 PUFA, higher mammary mRNA abundances of IL-1beta, TNF-alpha and XOR but lower mammary mRNA abundance of IL-10 than the FO-fed rats. Mammary inflammation around parturition appeared to be attenuated by consumption of a diet rich in n-3 PUFA, which was associated with up-regulated expression of IL-10 and PPAR-gamma.
    Lipids in Health and Disease 12/2013; 12(1):190. · 2.02 Impact Factor
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    ABSTRACT: Intra-uterine growth-retarded (IUGR) neonates have shown an impairment of postnatal intestinal development and function. We hypothesised that the immune function of IUGR neonates might be affected by increased nutrient intake (NI) during the suckling period. Therefore, we investigated the effects of high NI (HNI) on the growth performance, intestinal morphology and immunological response of IUGR and normal-birth weight (NBW) piglets. A total of twelve pairs of IUGR and NBW piglets (7 d old) were randomly assigned to two different nutrient-level formula milk groups. After 21 d of rearing, growth performance, the composition of peripheral leucocytes, serum cytokines and intestinal innate immune-related genes involved in the Toll-like receptor (TLR)-4-myeloid differentiation factor 88-NF-κB pathway were determined. The results indicated that IUGR decreased the average daily DM intake (ADMI) and the average daily growth (ADG). However, the ADMI and ADG were increased by HNI, irrespective of body weight. Likewise, serum cytokines (TNF-α and IL-1β) and ileal gene expressions (TLR-4, TLR-9, TRAF-6 and IL-1β) were lower in IUGR piglets, whereas HNI significantly increased blood lymphocyte percentage and serum IL-10 concentrations, but decreased neutrophil percentage, serum IL-1β concentrations and ileal gene expressions (NF-κB and IL-1β). Furthermore, IUGR piglets with HNI exhibited lower serum concentrations of TNF-α and IL-1β than NBW piglets, and these alterations in the immune traits of IUGR piglets receiving HNI were accompanied by decreasing ileal gene expressions of TLR-4, TLR-9, NF-κB and IL-1β that are related to innate immunity. In conclusion, the present findings suggest that increased NI during the suckling period impaired the immune function of neonatal piglets with IUGR.
    The British journal of nutrition 04/2013; · 3.45 Impact Factor
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    ABSTRACT: The study was conducted to compare the effects of XG with AG and BM at different metabolizable energy diets on growth performance, digestive physiology and energy utilization of broilers fed with corn-SBM diet. A 2 x 4 factorial design was used with two basal diets (the positive control group, PC; negative control with ME reduction 100 kcal/kg, NC) and with or without the addition of three exogenous enzymes (0.02% BM; 0.01% AG; 0.05% XG) respectively. 1,200 one-day-old broilers were randomly allocated to 8 treatments with 10 pens of 15 broilers. There was no significant difference on BW, BWG, and FI at 0-21d, 21-42d or 0-42d for diet, enzymes or their interactions, but FI at 22-42d and 0-42d were tend to be decreased with the addition of enzymes. The F/G was significantly improved by the addition of enzymes especially in NC diet. The dietary AME and TME in PC or NC diet were significantly increased by XG or AG in NC diet. The villus length and V/C of ileum were significantly increased by the addition of BM or XG. XG improved the activities of trypsin, chymotrypsin and amylase, BM improved the activity of trypsin at 21d, and AG improved the activity of chymotrypsin at 21d. Comparing to PC diet, the addition of enzymes in PC or NC diet decreased feed cost per kg body weight gain especially in NC diet (except AG in PC diet) with the highest profits for XG in NC diet. In conclusion, supplementation of 0.02% BM or 0.01% AG or 0.05% XG could improve feed conversion of broilers in corn-soybean meal diet by improving energy utilization and digestive physiology, and also supplementation of 0.05% XG had a preferable efficacy in low energy diet.
    Journal of animal science and biotechnology. 04/2013; 4(1):14.
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    ABSTRACT: Oxidative stress is detrimental to animals. Previous studies have indicated that arginine (Arg) may function as a potential substance against oxidative stress. The present study was conducted to explore the potential mechanisms behind the Arg-induced protective effects against oxidative stress in piglets. A total of thirty-six piglets were randomly allocated to six groups with six replicates per group. Piglets were subjected to three dietary treatments (namely two groups per treatment) in week 1 and fed with a basal diet (ArgL) or the basal diet supplemented with 0·8 % (ArgM) or 1·6 % (ArgH) l-Arg, respectively. On day 8, piglets were injected intraperitoneally either with diquat (10 mg/kg body weight) or sterile saline. The whole trial lasted 11 d. Results showed that dietary Arg supplementation did not affect growth performance in week 1. Oxidative stress significantly decreased the growth performance of piglets (P < 0·05). However, ArgH attenuated the negative effects of oxidative stress on feed intake and significantly increased the total antioxidant capacity in the liver under oxidative stress (P < 0·05). Both ArgM and ArgH enhanced the activities of plasma glutathione peroxidases and superoxide dismutases and decreased the IL-6 and TNF-α mRNA level in the liver under oxidative stress (P < 0·05). The present study not only shows that Arg can function as a potential nutrient to alleviate oxidative stress responses through the enhancement of antioxidant capacity, and inhibition of the expression of inflammatory cytokines, but the results also suggest that alleviation of oxidative stress responses using dietary nutrient components deserves further attention in the future.
    The British journal of nutrition 11/2012; · 3.45 Impact Factor
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    ABSTRACT: Tibetan pig is well known for its strong disease resistance. However, little is known about the molecular basis of its strong resistance to disease. Stimulator of interferon (IFN) genes (STING), also known as MPYS/MITA/ERIS/TMEM173, is an adaptor that functions downstream of RIG-I and MAVS and upstream of TBK1 and plays a critical role in type I IFN induction. Here we report the first cloning and characterization of STING gene from Tibetan pig. The entire open reading frame (ORF) of the Tibetan porcine STING is 1137 bp, with a higher degree of sequence similarity with Landrace pig (98%) and cattle (88%) than with chimpanzee (84%), human (83%) or mouse (77%). The predicted protein is composed of 378 amino acids and has 4 putative transmembrane domains. Real-time quantitative PCR analysis indicated that Tibetan pig STING mRNA was most abundant in the lung and heart. Overexpression of Tibetan porcine STING led to upregulation of IFN-β and IFN-stimulated gene 15 (ISG15) in porcine jejunal epithelial cell line IPEC-J2 cells. This is the first study investigating the biological role of STING in intestinal epithelial cells, which lays a foundation for the further study of STING in intestinal innate immunity.
    International Journal of Molecular Sciences 01/2012; 13(1):506-15. · 2.46 Impact Factor
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    ABSTRACT: Preterm neonates show enhanced sensitivity to nutrient maldigestion and bacteria-mediated gut inflammatory disorders, such as necrotising enterocolitis (NEC). We hypothesised that preterm birth increases the sensitivity of intestinal nutrient absorption to endotoxins and that feeding after birth reduces this response. Hence, we investigated the postnatal development of nutrient digestive and absorptive capacity in the preterm and term pig intestine, and its responsiveness to endotoxins. Pigs were delivered by caesarean section at preterm (n 20) or term (n 17) gestation, and the small intestine was collected at birth or after 2 d of colostrum feeding, followed by ex vivo stimulation with lipopolysaccharide endotoxins and mixed gut contents collected from pigs with NEC. Brush border enzyme activities were reduced in newborn preterm v. term pigs (39-45 % reduction, P < 0.05), but normalised after 2 d of feeding. Ex vivo leucine and glucose uptake increased with prenatal age. Bacterial stimulation reduced the nutrient uptake similarly at birth and after 2 d in preterm and term pigs (23-41 % reduction, P < 0.05), whereas IL-6 and TNF-α expression was stimulated only at birth. Toll-like receptor-4 expression increased markedly at day 2 for preterm and term pigs (22-33-fold, P < 0.05) but with much lower expression levels in newborn preterm pigs (approximately 95 %, P < 0.01). In conclusion, digestive and absorptive functions mature in the prenatal period, but are similarly affected by postnatal feeding and bacterial exposure in both preterm and term pigs. Nutrient maldigestion may contribute to NEC development, while a prematurity-related hyper-responsiveness to endotoxins could be less important, at least in pigs.
    The British journal of nutrition 12/2011; 108(4):672-81. · 3.45 Impact Factor
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    Jun He, Daiwen Chen, Keying Zhang, Bing Yu
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    ABSTRACT: Starch is the major energy source for monogastric mammals and humans. The present study was conducted to evaluate the liver metabolic responses of weaned pigs fed with different dietary starches. A total of sixteen weaned pigs were fed with two experimental diets containing either cassava starch (CS, 80 % amylopectin and 20 % amylose) or maize starch (70 % amylopectin and 30 % amylose). The present results showed that the growth performance was not affected by different dietary starches (P>0·05). However, ingestion of CS not only increased the lipid content in liver tissues, but also elevated the concentrations of serum cholesterol and insulin (P < 0·05). The metabolic responses induced by CS were associated with more lipogenic enzymes such as fatty acid synthase and 3-hydroxy-3-methyl-glutaryl-CoA reductase in liver (P < 0·05). Real-time PCR quantification for lipid metabolic genes indicated that ingestion of CS not only up-regulated the expression of these lipogenic genes, but also decreased the expression of lipolytic genes. These results suggested that the metabolic responses of weaned pigs fed with different dietary starches may vary widely depending on their composition, and ingestion of starches that are high in amylopectin may produce a stronger insulinaemic response and lead to an up-regulation of lipogenesis in the liver.
    The British journal of nutrition 06/2011; 106(10):1470-5. · 3.45 Impact Factor
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    ABSTRACT: The study was designed to investigate the effects of nutritional level (control diet (CD), 14.19% crude protein, 13.81MJ of DE/kg; low nutritional level diet (LND), 11.08% crude protein, 12.55MJ of DE/kg) on pork quality and gene expression of mu-calpain and calpastatin in muscle of finishing pigs. The LND treatment increased drip loss (P<0.05), had a trend to increase intramuscular fat (IMF) content (P=0.09), decreased Warner-Bratzler shear force (WBSF) of pork (P<0.05), improved mRNA level of mu-calpain (P<0.05) in skeletal muscle, but had no effect on gene expression of calpastatin, compared with the CD treatment. These data suggest that a moderately reduced energy and protein diet increased pork tenderness and intramuscular fat. The increase in tenderness by LND treatment may be partly due to increased gene expression of mu-calpain in muscle.
    Meat Science 08/2010; 85(4):768-71. · 2.75 Impact Factor
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    ABSTRACT: To investigate the deposition and elimination of melamine in hen eggs and tissues, 72 Roman laying hens were administrated with melamine at 8.6-140.9 mg per kilogram of body weight per day for 34 days. The crystals were found in one of three kidneys of hens treated with melamine at either 62.6 or 140.9 mg/kg. Furthermore, the melamine concentrations in egg, muscle, liver, kidney, stomach, duodenum, uterus, ovary, and blood plasma were determined by high-performance liquid chromatography-ultraviolet (HPLC-UV) methods. A higher dosage of melamine in the diet corresponded to higher concentrations in tissues and eggs. The concentrations of melamine in tissues were in the following ranges (microg/g): egg, 1.1-28.7; muscle, 0.4-9.3; liver, 0.5-6.9; kidney, 1.3-21.7; stomach, 0.4-7.3; duodenum, 0.3-2.8; uterus, 0.5-6.9; ovary, 0.5-9.1; and blood plasma, 0.8-7.6. When melamine was withdrawn from the diet of hens, the melamine concentration in hen tissues fell to below 2.5 microg/g by day 10 and no residues were detected in eggs or tissues at days 7 and 20, respectively.
    Journal of Agricultural and Food Chemistry 04/2010; 58(9):5414-20. · 2.91 Impact Factor
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    ABSTRACT: The scandal of melamine-adulterated infant formula in China in September 2008 demanded the need to assess the extent of melamine contamination in the environment and food products and possible risks of consuming melamine-contaminated diets. In this work, our extensive work tested water, soil and crop samples from 21 provinces in China. Soils nearby and waste waters from melamine-manufacturing factories were examined, and the highest melamine concentrations in waste water and soil samples were 226.766 and 41.136 mg/kg, respectively. Six of 94 irrigation water samples had melamine at a concentration of 21-198 microg/L. Only 1 sample collected from 124 farmlands farther than 150 km from melamine factories was detected for melamine at a content of 176 microg/L. Only 3 out of 557 crop samples contaminated more than 1mg/kg melamine, with the highest level of 2.05 mg/kg in a wheat sample. When basal diets contained 2mg/kg melamine were fed to various animals, deposition of melamine in animal tissues and products was all lower than 122 microg/kg. The melamine deposition was much higher (e.g., 4483 microg/kg in the kidney of chicken) when diets contained 100 mg/kg melamine but was found to be completely depleted after 96 h for all animals after switching to the basal diets. Our work may be valuable to regulate melamine production and monitor the safety of food and animal products.
    Environment international 04/2010; 36(5):446-52. · 4.79 Impact Factor
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    ABSTRACT: Sulfur amino acids (SAA), particularly methionine and cysteine, are critical for the gut to maintain its functions including the digestion, absorption and metabolism of nutrients, the immune surveillance of the intestinal epithelial layer and regulation of the mucosal response to foreign antigens. However, the metabolism of SAA in the gut, specifically the transmethylation of methionine, will result in a net release of homocysteine, which is shown to be associated with cardiovascular disease and stroke. Furthermore, the extensive catabolism of dietary methionine by the intestine or by luminal microbes may result in a decrease in nutritional efficiency. Therefore, the regulation of SAA metabolism in the gut is not only nutritionally relevant, but also relevant to the overall health and well-being. The superiority of DL-2-hydroxy-4-methylthiobutyrate to DL-methionine in decreasing homocysteine production, alleviating stress responses, and reducing the first-pass intestinal metabolism of dietary methionine may provide a promising implication for nutritional strategies to manipulate SAA metabolism and thus to improve the nutrition and health status of animals and perhaps humans.
    Amino Acids 02/2010; 39(3):633-40. · 3.91 Impact Factor
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    ABSTRACT: To gain insights into the effects of tea polyphenols (TP) on growth performance and cell-mediated immune response of piglets under oxidative stress, an oxidative stress model was established by intraperitoneally injecting weaned piglets with diquat. After intake of either basal diet or TP-supplemented diet for 7 d, half of the piglets in each group were challenged with diquat. Results showed that dietary TP alleviated growth depression to some extent. A T lymphocyte transformation test (LTT) demonstrated that TP promoted the proliferation and activation of T lymphocytes. The ratio of CD4+/CD8+ was elevated, indicating a recovering tendency from immune damages caused by oxidative stress. The increment of pro-inflammatory IL-1 caused by oxidative stress was attenuated, and the concentration of serum IFN-gamma was decreased by TP-supplementation. However, the serum concentrations of anti-inflammatory cytokine, such as IL-4, were greatly enhanced by TP, which suggested an immune shift from Th1 to Th2. These findings supported the immunomodulatory potential of TP for piglets subjected to oxidative stress.
    Archives of animal nutrition 02/2010; 64(1):12-21. · 1.10 Impact Factor
  • Jun He, Daiwen Chen, Bing Yu, Keying Zhang
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    ABSTRACT: In this study, an optimization of xylanase expression by recombinant Pichia pastoris was carried out with a 23 factorial design. The influence of initial cell density, methanol and yeast nitrogen base concentration was evaluated, and the cell density was found to be the most important parameter. Considering with the yield of enzyme activity and the amount of methanol and YNB used for fermentation, the optimal conditions in this study for enzyme production were 0.5% (w/v) methanol, 0.8% (w/v) YNB, and initial cell density of 3×108cells/ml. The enzyme production in 15-l fermenter with the optimized conditions was performed and a twofold higher xylanase activity was obtained. The produced enzyme was practically free of cellulolytic activity. The molecular mass (21kDa), optimal pH (6.0) and substrate specificity of the enzyme were both identical to native enzyme. However, the thermostability of the recombinant enzyme was better than the native enzyme. The optimal temperature for the recombinant Xyn2 was 5°C higher than native Xyn2, and remained at least 90% of its activity after 30min incubation at 55°C. The high level of fully active recombinant xylanase obtained in P. pastoris makes this expression system attractive for fermenter growth and industrial applications.
    Biochemical Engineering Journal - BIOCHEM ENG J. 01/2010; 52(1):1-6.
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    ABSTRACT: IUGR and preterm birth are leading causes of neonatal morbidity. We tested the hypothesis that IUGR predisposes to gut maladaption and necrotizing enterocolitis (NEC) using preterm pigs as models for preterm infants. First, full-term normal birth weight (NW) and IUGR ( approximately 65% of NW) pigs were compared. IUGR reduced intestinal weight per length, proportion mucosa, villous area, and sucrase activity at 2 d after birth (p < 0.05) but did not change relative organ weights. Next, groups of preterm pigs were fed formula or colostrum, starting at birth or after 2-3 d of total parenteral nutrition (TPN). Neonatal mortality (not related to NEC) was increased in IUGR versus NW preterm pigs (28 vs 10%, p < 0.01). NEC incidence was similar between IUGR and NW but higher after formula than colostrum feeding (46 vs 12%, p < 0.01) and higher after TPN than without TPN (61 vs 34% for formula pigs, p < 0.01). After feeding, relative intestinal mass and length were higher in IUGR versus NW pigs (+25-80%, p < 0.05) while brush border enzyme activities were similar. An enhanced gut trophic response to enteral feeding may help to improve postnatal intestinal adaptation and NEC resistance in preterm IUGR newborns. ABBREVIATIONS::
    Pediatric Research 09/2009; 67(1):54-9. · 2.67 Impact Factor
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    ABSTRACT: In recent years, xylanases have attracted considerable research interest because of their potential in various industrial applications. The yeast Pichia pastoris can neither utilize nor degrade xylan, but it possesses many attributes that render it an attractive host for the expression and production of industrial enzymes. The Xyn2 gene, which encodes the main Trichoderma reesei Rut C-30 endo-beta-1, 4-xylanase was cloned into the pPICZalphaA vector and expressed in Pichia pastoris. The selected P. pastoris strains produced as 4,350 nkat/ml beta-xylanase under the control of the methanol inducible alcohol oxidase 1 (AOX1) promoter. The secreted recombinant Xyn2 was estimated by SDS-PAGE to be 21 kDa. The activity of the recombinant Xyn2 was highest at 60 degrees C and it was active over a broad range of pH (3.0-8.0) with maximal activity at pH 6.0. The enzyme was quite stable at 50 degrees C and retained more than 94% of its activity after 30 mins incubation at this temperature. Using Birchwood xylan, the determined apparent Km and kcat values were 2.1 mg/ml and 219.2 S-1, respectively. The enzyme was highly specific towards xylan and analysis of xylan hydrolysis products confirmed as expected that the enzyme functions as endo-xylanase with xylotriose as the main hydrolysis products. The produced xylanase was practically free of cellulolytic activity. The P. pastoris expression system allows a high level expression of xylanases. Xylanase was the main protein species in the culture supernatant, and the functional tests indicated that even the non-purified enzyme shows highly specific xylanase activity that is free of cellulolytic side acitivities. Therefore, P pastoris is a very useful expression system when the goal is highly specific and large scale production of glycosyl hydrolases.
    BMC Biotechnology 07/2009; 9:56. · 2.17 Impact Factor
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    Renyong Tang, Bing Yu, Keying Zhang, Daiwen Chen
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    ABSTRACT: Twenty-four crossbred (Duroc × Large White × Yorkshire) finishing pigs (halothane-negative, mean live weight of 90 kg) were used to determine the effects of supplementing swine finishing diets with magnesium aspartate (MgAsp) and short-duration transportation stress on blood parameters, pork quality and μ-calpain and calpastatin mRNA levels in muscle of pigs. Transportation increased serum concentrations of calcium (Ca) (P < 0.05), phosphorus (P) (P < 0.01), glucose (P < 0.01) and cortisol (P < 0.01). Supplementation of MgAsp increased concentration of serum Mg (P = 0.057). Transportation decreased L⁎ value (P < 0.05) of biceps femoris (BF) at 45 min and 24 h, and b⁎ value of longissimus thoracis (LT) at 45 min (P = 0.073) after slaughter, and increased pH value of BF at 45 min (P < 0.05) and LT at 45 min (P = 0.098) after slaughter. However, transportation increased Warner–Bratzler shear force (WBSF) value of BF (P < 0.05) at aging 72 h and LT (P < 0.01) at aging 24 h and 72 h. Supplementation of MgAsp reduced L⁎ value (P < 0.05) of LT at 45 min, and BF at 45 min and at 24 h after slaughter, increased a⁎ value (P < 0.05) of BF at 45 min and had a trend to decline WBSF values of BF and LT at aging 24 h compared with the treatments fed the control diet. Transportation improved mRNA level of calpastatin of muscle (P < 0.05). Meanwhile, supplementation of MgAsp increased mRNA level of μ-calpain of muscle (P = 0.079). These results suggested that transportation stress increased postmortem color and pH value of pork and decreased tenderness of pork, and supplemental MgAsp improved color of pork and had a trend to decline WBSF, but did not influence drip loss and pH value of pork.
    Livestock Science. 01/2009;
  • Renyong Tang, Bing Yu, Keying Zhang, Daiwen Chen
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    ABSTRACT: The objective of this study was to investigate the effects of supplementing swine finishing diets with two levels of magnesium aspartate (MgAsp) and short-term transportation stress on blood parameters, pork quality and the mRNA abundance of p-calpain and calpastatin in muscles of finishing pigs. Thirty-six crossbred finishing pigs (mean BW 90 kg) were assigned randomly to 0, 1000, or 2000 mg supplemental Mg from MgAsp per kg of diet for five days before slaughter. Then six pigs from each dietary treatment were subjected either to no transportation stress (NTS) or 2 h of transportation stress (TS). Transportation stress resulted in higher concentrations (p < 0.01) of serum calcium, glucose and cortisol, lower pH (p < 0.01), higher Warner-Bratzler shear force (WBSF) (p < 0.05) and higher calpastatin mRNA abundance (p = 0.05) of longissimus muscle (LM) compared with NTS treatments. Supplementation of MgAsp in TS treatments increased serum Mg concentration (p < 0.05) at 2000 mg of Mg/kg, reduced drip loss (p < 0.05) and improved pork quality colour (p < 0.05) at 2000 mg of Mg/kg, and decreased 1-day and 3-day WBSF (p < 0.05) at 1000 mg of Mg/kg compared with TS treatments fed the control diet. It is concluded that supplementation of MgAsp improves water-holding capacity and pork colour, and alleviates the negative effects of transportation stress on meat tenderness.
    Archives of animal nutrition 10/2008; 62(5):415-25. · 1.10 Impact Factor
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    ABSTRACT: The c-Jun N-terminal kinase (JNK) pathway was reported to be involved in myostatin signaling and MKK4 was suggested as the only upstream kinase for myostatin-induced JNK activation, implying that MKK4 is a suitable target of RNA interference (RNAi) for blocking myostatin activity. The aim of this study was to evaluate the effect of small interfering RNA (siRNA) targeted against MKK4 on myostatin-induced downregulation of differentiation marker gene expression. Real-time quantitative PCR revealed that the level of MKK4 expression was efficiently reduced by MKK4-specific siRNA. Western blot assays showed that knockdown of MKK4 attenuated the myostatin-induced downregulation of MyoD and myogenin expression.
    Molecular and Cellular Biochemistry 04/2008; 310(1-2):241-4. · 2.33 Impact Factor
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    ABSTRACT: This study was conducted to investigate the effects of active immunization against cholecystokinin 8 (CCK(8)) on the content of serum CCK, expression of CCK, and CCK receptor gene in pigs. The subjects for this experiment were 15 pigs divided into three groups (5 pigs per group). The treated groups were immunized with CCK(8) conjugated to human serum albumin (HSA). The control group was immunized with same dosage of HSA. The average daily gain of pig fed with 250 microg CCK was significantly increased (P < 0.05), compared with the control group (0 microg CCK). The content of CCK(8), insulin, and leptin in serum was significantly (P < 0.05) decreased and the titer of CCK(8) antibody was significantly (P < 0.05) increased in treated groups compared to the control group. The levels of CCK gene and CCK receptor gene expression in jejunum, pituitary, and pancreas of the treated groups were significantly (P < 0.05) lower than that of the control group. It is concluded that optimal active immunization against CCK(8) could increase the content of CCK antibody and suppress CCK gene and CCK receptor gene expressions and in result improve feed intake and growth performance of pigs.
    Endocrine 12/2007; 32(3):338-44. · 2.25 Impact Factor