Effect Of Chronic Oxidative Stress On Meat Quality And Digesti VE Metabolism Of Broilers

In order to study whether cortisone could induce oxidative stress by drinking water and how does oxidative stress effect on meat quality and digestive metabolism of broilers, four experiments were involved. Experiment 1 Arbor Acres chicks were used in the experiments. On the age of 21d, 320 male chickens were randomly divided into four groups by weights.Eight pens in a group and each pen with 10 chicks. Cortisone was applied to the birds via drinking water for 10 d. GroupsⅠ,Ⅱ,Ⅲ,Ⅳwere treated with 0㎎/L,10㎎/L,20㎎/L,30㎎/L, respectively. Feed and water were provided ad libitum. Blood samples were taken at 0 d,1 d,2 d,3 d,6 d,10 d for serum corticosterone (CS),glucose(GLU),thyroid hormone concentration and indicators of peroxidation state. Blood samples were always taken at 9:00, to prevent measurement of differences because of the circadian rhythm. The experiment conducted from 21d to 31d. The results indicated that: Compared with control group,Ⅳgroup significantly elevated both CS and GLU concentrations at 3d,2d respectively. T3,T4 concentrations varied in a wide range throughout the experiment.T3 concentrations droped obviously at 1～2d but T4 concentrations elevated at 3d. Indictors of peroxidation state showed that compared with control group, MDA increased significantly at 1～3d,6d ,respectively; SOD activity decreased significantly at 1d,3d, GSH-PX activity decreased at 1～3d; T-AOC activity decreased at 2d; CK increased at 6d. All the results indicated thatⅣgroup had successfully induced oxidative stress through cortisone by drinking water.Experiment 2 In this experiment, effects of chronic oxidative stress on peroxidation state of tissue and grown immune organs of broilers were studied. The results showed that. There were no obviously influence on growth of hearts and livers(P>0.05); except spleens increased relative weight ,all the immune organs had no obviously influence by chronic oxidative stress(P>0.05). The same result was observed in abdominal fat(P>0.05); chronic oxidative stress had little influence on liver moisture but had significantly increased liver lipid at 10d(P<0.01); chronic oxidative stress had significantly increased heart MDA at 2～3d(P<0.01),however, chronic oxidative stress had significantly decreased MDA at 10d, significantly increased GSH-PX(P<0.01)at 1d but decreased SOD significantly (P<0.05)at the same day ; chronic oxidative stress had significantly increased livers MDA at 2～3d(P<0.01),had significantly decreased GSH-PX,SOD activity throughout the test period except 6d(P<0.01). All the results indicated that chronic oxidative stress had little influence on grown immune organs of broilers, but significantly effected on peroxidation state of tissue. Experiment 3 In this experiment, chronic oxidative stress on meat quality of broilers was studied. Chronic oxidative stress had significantly increased water drop both of breast and thigh(P<0.01)at 6d and 10d. Chronic oxidative stress had significantly increased breast PH of 45min, but had little increased thigh PH of 45min, on the country, chronic oxidative stress had little increased breast PH of 24h, excepted 3d, had no obvious effect on thigh PH of 24h, but in a rising trend. Chronic oxidative stress had no influence on relative weight of breast and thigh, had no influence on moisture and protein content of breast, had decreased lipid of breast at 2d,6d, compared with control , groupsⅢhad decreased moisture of thigh at 2d,6d significantly(P<0.05), groupsⅡ,Ⅲhad decreased protein content of thigh at 6d, groupsⅡ,Ⅲhad decreased lipid of thigh at 6d, and groupsⅢhad decreased lipid of thigh at 2d.All the results indicated that Chronic oxidative stress had little influence on relative weight of meat tissue, but decreased nutrient content significantly(P<0.05).Experiment 4 In this experiment, effect of chronic oxidative stress on digestion and metabolism of broilers was studied. Chronic oxidative stress had little influence on weight gain,feed intake and F/G(P>0.05),the same results were observed in HLD,LDL,CHO,TG,Gre(P<0.05). Compared with control, groupsⅢhad significantly increased TP at 10d(P<0.05), and groupsⅣhad significantly increased ALB,AST at 10d,1d respectively (P<0.05). Chronic oxidative stress caused decreace in digestion of nutrients.Compared with control, groupsⅢ,Ⅳdecreased apparent digestibility of protein and fat at 3～4d(P<0.05), and decreased apparent digestibility of crude ash at 1～2,3～4d. All the results indicated that chronic oxidative stress had significantly effect on apparent digestibility of feed in broilers.