Yuming Guo

Effects of supplementation with vitamin E on the performance and the tissue peroxidation of broiler chicks and the stability of thigh meat against oxidative deterioration

Two experiments were conducted: Expt 1 determined the optimal allowance of vitamin E in the diet for broiler chicks aged 0-3 weeks; Expt 2 investigated the effects of different dietary levels of vitamin E (α-tocopherol) on the performance and the oxidative stability of thigh meat of broiler chicks during storage. In Expt 1. 1-day-old 900 broiler chicks were allocated to five treatments, each with six replicates (cages) of 22 as-hatched chicks for performance evaluation, and another cage of 45 male chicks for determining plasma and hepatic α-tocopherol and thiobarbituric acid reactive substances (TBARS) concentration in blood and liver. The basal dietary α-tocopherol concentration was 13 mg/kg, and the five α-tocopherol acetate supplementation levels were 0, 5, 10, 50 and 100 mg/kg. For 0-3-week-old broiler chicks fed with maize-soya bean meal-soya oil type diet, supplementation of vitamin E did not influence the feed intake, but tended to improve growth and feed utilization, however there was no significant correlation between performance and vitamin E supplementation level. Significant positive correlations existed between dietary supplemental vitamin E level and plasma or hepatic α-tocopherol concentrations (P < 0.05), and a negative correlation with hepatic TBARS levels no matter at what age (11, 16 and 21 days). In Expt 2, 2200 broiler chicks were randomly allocated to five treatments with four replicates (pens) in each. Chicks were fed ad libitum five pellet diets supplemented with vitamin E at 5, 10, 20, 50 and 100 mg/kg of diet, respectively. The basal dietary α-tocopherol level of grower and finisher diets were 7 and 6 mg/ kg, respectively, Supplementation of vitamin E tended to improve growth and feed utilization of birds during 0-3 weeks of age, but the performance from 0 to 6 weeks of age were not influenced. The hepatic α-tocopherol concentrations of 6-week-old chicks linearly increased with the dietary vitamin E levels (R 2 = 0.98, P < 0.001). The content of TBARS in the thigh meat over 4 days of storage under 4°C was significantly decreased by increasing dietary vitamin E level (P < 0.05). There was a significant inverse relationship between TBARS value in the thigh meat and the dietary vitamin E level (R 2 = 0.93, P < 0.01). Supplementation of vitamin E significantly improved the meat quality stability substantially against oxidative deterioration. Comparing the hepatic α-tocopherol levels of chicks in Expts 1 and 2, total allowance of dietary α-tocopherol of 20-30 mg/ kg could sustain relatively constant hepatic α-tocopherol level at round about 2-2.5 μg/kg.

Effects of source and level of magnesium and Vitamin E on prevention of hepatic peroxidation and oxidative deterioration of broiler meat

Experiment 1 was conducted to investigate the influences of source and level of dietary magnesium (Mg) supplementation on performance of broilers, thigh meat pH and oxidative deterioration during storage. Five hundred and sixty 1-day-old broiler chicks were allotted to seven treatments, each one had four replicates (cages) of 20 chicks. The basal dietary Mg contents of the maize-soya bean meal diets were 1.9 and 2.1 g/kg for starter and grower, respectively, and the three organic Mg (proteinate) or inorganic Mg (oxide) supplementation levels were 0.5, 1.0 and 2.0 g/kg, respectively. Mg supplementation level did not influence feed intake and growth performance of chicks. Thigh meat pH was not influenced by the oxide Mg, but was elevated quadratically (R 2 = 0.999), P < 0.01) by increased dietary inclusion level of the proteinate Mg. Thiobarbituric acid reactive substance (TBARS) in the thigh muscle stored over 4 days at 4°C tended to decrease by both the oxide and the proteinate Mg supplementation, and a negative correlation between the meat TBARS value and the proteinate Mg supplementation level existed (R 2 = 0.987, P = 0.058). In Experiment 2, 432 broiler chicks were randomly allocated into six treatments with three replicates (cages) each of 24 birds. The dietary Vitamin E supplementation level was 100 mg/kg, and Mg inclusion level was 2.0 g/kg as the oxide or as the proteinate, respectively. The results showed that addition of Vitamin E at 100 mg/kg significantly improved (P < 0.05) the growth and feed conversion ratio of broilers fed the control diet during 0-3 weeks of age. Vitamin E significantly (P < 0.05) decreased TBARS values of the hepatic tissue and the thigh meat during storage, but did not influence activities of hepatic catalase (CAT) and superoxide dismutase (SOD). Mg supplementation in both forms did not significantly influence the growth of birds, but proteinate Mg supplementation at 2.0 g/kg did improve the feed conversion of control birds during 0-3 weeks, and the difference between Mg sources was significant (P < 0.05). Mg supplementation significantly (P < 0.01) reduced the TBARS values in the liver and the thigh muscle, and the proteinate Mg was more efficient than the oxide (P < 0.01), but there was no interaction between Mg and Vitamin E. Mg supplementation significantly elevated the activity of catalase (P < 0.01) and tended to increase the activity of superoxide dismutase (0.05 < P < 0.10), but there were no significant differences between two sources of Mg. The results suggest that Mg has the capability of reducing oxidation, and could be used to improve and stabilize chicken meat quality; the proteinate Mg is more efficient than the oxide.

Effects of dietary coenzyme Q10 supplementation on hepatic mitochondrial function and the activities of respiratory chain-related enzymes in ascitic broiler chickens

1. One hundred and sixty 1-d-old Arbor Acre male broiler chicks were fed with maize–soybean based diets for 6 weeks in a 2u2009×u20092 factorial experiment. The factors were CoQ10 supplementation (0 or 40u2009mg/kg) and Escherichia coli lipopolysaccharide (LPS) challenge (LPS or saline). 2. CoQ10 was supplemented from d 1. From d 18, the chickens received three weekly i.p. injections of LPS (1·0u2009mg/kg BW) or an equivalent amount of sterile saline as control. From d 10 on, all chickens were exposed to low ambient temperature (12 to 15°C) to induce ascites. 3. The blood packed cell volume and ascites heart index of broiler chickens were reduced by dietary CoQ10 supplementation. Mitochondrial State 3 and State 4 respiration, respiratory control ratio and phosphate oxygen ratio were not changed, but H+/site stoichiometry of complex IIu2009+u2009III was elevated by dietary CoQ10 supplementation. 4. Cytochrome c oxidase and H+-ATPase activity were increased by CoQ10 supplementation, whereas NADH cytochrome c reductase and succinate cytochrome c reductase were not influenced. Mitochondrial anti-ROS capability was increased and malondialdehyde content was decreased by CoQ10 supplementation. 5. The work suggested that dietary CoQ10 supplementation could reduce broiler chickens’ susceptibility to ascites, which might be the result of improving hepatic mitochondrial function, some respiratory chain-related enzymes activities and mitochondrial antioxidative capability.

Dietary taurine impairs intestinal growth and mucosal structure of broiler chickens by increasing toxic bile acid concentrations in the intestine

Three experiments were conducted to determine the effect of taurine on the intestinal development, bile acid concentrations, and hormonal status of chickens. In experiment 1, a total of 250 one-day-old broilers were randomly allocated to 5 treatments and supplemented with 0, 0.25, 0.50, 1.00, and 2.00 g/kg of taurine, respectively. Growth performance, weight and length of the small intestine, and intestinal morphology were measured on d 7, 22, and 44. The gene expression levels of several hormones, including epidermal growth factor and cholecystokinin, were also evaluated. In experiment 2, 60 one-day-old broilers were supplemented with 0, 1.0, and 5.0 g/kg of taurine to assess cell proliferation in the jenunal crypt. In experiment 3, 100 newly hatched broilers were assigned randomly to 5 treatments (0, 0.10, 0.50, 2.00, 8.00 g/kg of taurine) to evaluate the bile acid concentrations in the jejunal mucosa. Our results indicated that dietary taurine decreased the length and weight of small intestine, the villus width, surface area, and crypt depth in the duodenum and jejunum (P < 0.05). Taurine also increased the expression of cholecystokinin and epidermal growth factor on the jejunal mucosa (P < 0.001). Taurine has little effect on stimulating the proliferation of intestinal crypt cells, except for 5 g/kg of taurine supplementation on d 14 (P < 0.05). Additionally, a linear increase in the jejunal concentrations of taurocholic acid, taurochenodeoxycholic acid, and taurolithocholic acid was observed on d 7 in broilers fed increasing levels of taurine. In conclusion, we suggested that taurine impairs intestinal mucosal development partly through generation of toxic bile acids.

Sodium hydrosulfide prevents hypoxia-induced pulmonary arterial hypertension in broilers

1. The aim of the study was to determine if H2S is involved in the development of hypoxia-induced pulmonary hypertension in broilers, a condition frequently observed in a variety of cardiac and pulmonary diseases. 2. Two-week-old broilers were reared under normoxic conditions or exposed to normobaric hypoxia (6u2009h/day) with tissue levels of H2S adjusted by administering sodium hydrosulfide (NaHS, 10u2009µmol/kg body weight/day). Mean pulmonary arterial pressure, right ventricular mass, plasma and tissue H2S levels, the expression of cystathionine-β-synthase (CSE) and vascular remodeling were determined at 35u2009d of age. 3. Exposure to hypoxia-induced pulmonary arterial hypertension was characterized by elevated pulmonary pressure, right ventricular hypertrophy and vascular remodeling. This was accompanied by decreased expression of CSE and decreased concentrations of plasma and tissue H2S. 4. Hypoxia-induced pulmonary hypertension was significantly reduced by administration of NaHS but this protective effect was largely abolished by D, L-propargylglycerine, an inhibitor of CSE. 5. The results indicate that H2S is involved in the development of hypoxia-induced pulmonary hypertension. Supplementing NaHS or H2S could be a strategy for reducing hypoxia-induced hypertension in broilers.