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Articles by H.W. Cheng
Total Records ( 3 ) for H.W. Cheng
  J.N. Felver-Gant , R.L. Dennis , J. Zhao and H.W. Cheng
  Heat stress (HS) causes oxidative damage, increasing mortality and reducing productivity in chickens. The objective of this study was to determine the benefits of antioxidant supplementation in laying hens during HS. Eighty 32-week-old W-36 White Leghorn hens were used in this study. Hens were randomly pair-housed in two adjacent rooms and fed a control diet (CF) or control diet mixed with Agrado Plus Ultra®, an antioxidant, at 160 mg/kg (AF) for two weeks. One room was then subjected to a hot climate (H) (33°C) for 8 days. Physical and physiological data were collected at day 1 and 8 during the treatment. Core body temperature was increased (p<0.0001) and BW (p<0.05) and liver weight (p<0.0001) were reduced in laying hens regardless of treatment. However, compared to its respective controls, the concentrations of heat shock protein 70 (HSP70) were increased in H-AF hens (p< 0.01) but not in H-CF hens (p>0.05) at 8 days during the process of HS. Similarly, HSP70 mRNA expression tended to increase in H-AF hens only (p = 0.09). Heat stress reduced the concentrations of total CO2 and bicarbonate (p<0.05), indicating respiratory alkalosis and decreased vitamin A (p<0.01), vitamin E (p<0.0001) and glutathione peroxidase (p<0.05) concentrations but increased protein carbonyl concentrations (p<0.05), indicating protein oxidative damage. A temperature by feed interaction was observed in the concentrations of partial pressure CO2 (pCO2, p<0.05), superoxide dismutase (SOD, p = 0.06) and protein carbonyl (p = 0.1). Heat stress-caused decreases in pCO2 and SOD and increases in protein carbonyl concentrations were found in control hens but not in AF hens. These results suggest antioxidant supplementation attenuates oxidative stress response in laying hens. These data support the hypothesis that supplemental antioxidants improve hen well-being by reducing HS associated physical and physiological damage.
  H. Chen , F.F. Yan , J.Y. Hu , Yanan Wu , C.M. Tucker , A.R. Green and H.W. Cheng
  Background and Objective: Ammonia (NH3) is one of the most prominent aerial pollutants inside poultry barns, affecting chicken health and well-being based on its level and exposure duration. The aim of this study was to investigate the effect of 30 ppm NH3 on the immune response of laying hens. Methodology: Hy-Line W-36 hens at 18 weeks of age were randomly assigned to 4 hen cages and evenly distributed to two controlled environment chambers. Beginning at 25 weeks of age, one chamber was maintained continuously with fresh air (NH3 < 5 ppm; control group) and the other one was injected with NH3 and controlled at 30 ppm (NH3 group) for 25 weeks. At 50 weeks of age, plasma concentrations of total immunoglobulins (IgA, IgG and IgM), complement factors (C3 and C4), albumin (ALB), Alpha-1-acid glycoprotein (AGP) and cytokines including interleukin (IL)-1β, IL-6, interferon gamma (IFN-γ) and Tumor Necrosis Factor alpha (TNF-α) as well as mRNA expressions of IL-1β, IL-6 and TNF-α in the spleens were determined (n = 16). Results: Hens exposed to NH3 had a greater Heterophil/Lymphocyte (H/L) ratio (p<0.05) but lower plasma concentrations of IgM and C4 (p<0.05, respectively) than control hens. There were no differences in the concentrations of other measured parameters between NH3 exposed hens and control hens (p>0.05, respectively). Conclusion: These findings suggested that NH3 exposure at 30 ppm for 25 weeks increases stress status and suppresses immunity of laying hens as indicated by the changes of H/L ratio and plasma IgM and C4 concentrations.
  U.T. Mahmoud , O.A. Amen , T.J. Applegate and H.W. Cheng
  Objective: This study aimed to examine the effect of dietary Brazilian propolis on the growth performance, physiological homeostasis and gut characteristics in broiler chickens reared under mild chronic heat stress. Materials and Methods: Five hundred and four 15 days old male broiler chicks were fed one of six diet (0.0, 100, 250, 500, 1000 and 3000 mg kg–1 propolis). Growth performance was evaluated in terms of Body Weight (BW), Body Weight Gain (BWG), Feed Intake (FI) and Feed Conversion Ratio (FCR) at 2 weeks intervals to 42 day of age. At 42 day of age 12 birds from each group were randomly selected and sacrificed for determination of the relative weight of internal organs and cecal contents were collected for microbial enumeration. Duodenal, jejunal and ileal tissue samples were collected for measuring villus height and width, crypt depth and villus crypt ratio. Also, blood was collected for subpopulations of leukocytes counts and serum chemical and hormonal analysis. In addition, brain samples were collected for determination of the heat stress-induced changes of the Heat Shock Protein 70 (HSP70) gene expression. The data were analyzed by one-way analysis of variance using the General Linear Models (GLM) procedure. Results: The results indicated that dietary propolis supplementation had no effect on growth performance and liver, heart, gizzard and spleen weights (p>0.05). While, compared to controls, the abdominal fat weight was increased with propolis supplementation (p = 0.035). Propolis did not affect cecal concentrations of Escherichia coli, total coliforms, Enterococcus spp. and total lactobacilli (p>0.05). However, compared to controls, the Bifidobacterium spp., population was lower in birds fed diet with propolis at 1000 mg kg–1 (p = 0.005). Propolis had no effect (p>0.05) on intestinal villus height and width, crypt depth and villus:crypt ratio. Compared to controls, propolis dietary supplementation did not affect the populations of eosinophils, monocytes and basophils; and serum concentrations of total proteins, globulins, phosphate, calcium, glucose and thyroid hormones as well as HSP70 mRNA expression in brain tissues (p>0.05, respectively). However, propolis regardless of dose reduced the number of heterophils, heterophil:lymphocyte ratio (H/L) and serum corticosterone and aminotransferase (AST) concentrations (p<0.05, respectively). In addition, all doses of propolis, except for 100 mg kg–1, significantly increased circulating lymphocytes and reduced uric acid concentrations. In addition, there was an effect of propolis on serum albumin and tri-iodothyronine:thyroxin (T3/T4) ratio. Compared to the control group, birds fed 250 mg kg–1 propolis had a significantly higher T3/T4 ratio; while both 100 and 3000 mg kg–1 propolis groups had significantly increased the serum albumin concentrations. Conclusion: It is concluded that dietary supplementation of green Brazilian propolis at the tested doses, improves health status of birds by reducing initiation of heat stress responses, such as reduced concentrations of corticosterone, H/L ratio, AST and uric acid and increased T3/T4 ratio.
 
 
 
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