Effects Of Selenium, Iodine And Their Interaction On Anti-oxidative Capability In Laying Hens

Five experiments were conducted to study the effects of different doses of selenium and iodine on antioxidant ability of laying hens. At the level of the mRNA gene expression of ID-I, GPx-4 and UCP3, the nutritional interaction of selenium and iodine were investigated.In Expl. The effects of dietary selenium and iodine on the serum thyroxine and liver selenium nutrition in laying hens were examined. The serum concentration of thyroxine was changed with selenium deficiency and there was a significant dose-response between different selenium supplementation levels (PO.05); the concentration of selenium and the activity of GPx (PO.05) in the liver was decreased with selenium deficiency but there was no difference observed between different selenium supplementation levels; the serum thyroxine (P<0.05) were decreased in a short time of iodine deficiency but no difference in serum T3 was observed between 0 and 0.1 mg/kg iodine after long time iodine deficiency; the interaction of selenium and iodine resulted in a difference in inferior egg production (P<0.05) and when the selenium was supplemented with 0.05 mg/kg and iodine with 0 or 0.2 mg/kg, the hens produced more inferior eggs than the others (PO.05).In Exp2. The effects of dietary selenium and iodine on the thyroid hormone metabolism and anti-oxidative enzyme activity in the different tissues of laying hens were examined. The activity of GPx in the heart and liver decreased in the selenium deficiency treatment; the activity of CAT in the heart (P=0.042) and liver (P=0.073) decreased, and the activity of GPx in the liver (P=0.093) decreased in the iodine deficiency treatment; The interaction of selenium and iodine can affect the activity of T-SOD and CAT in the heart and liver significantly (P<0.05). The ratio of T-SOD/(CAT+ GPx) was affected by the interaction of selenium and iodine (P<0.01). The concentration of T4 in the heart and liver increased (P = 0.050 and 0.098) in the selenium deficiency treatment, but the concentration of T3 in the thyroid gland, the activity of 5'ID-I in the thyroid (P<0.01) decreased; The concentration of T3 in the liver increased (P<0.01) in the iodine deficiency treatment, but the activity of 5'ID-I in the thyroid gland (PO.01) decreased; the interaction of selenium and iodine can affect the concentration of T4 in the heart (P=0.054). The results indicate that selenium nutrition can affect the thyroid hormone metabolism in heart, liver and thyroid and there is a nutritional interaction between selenium and iodine on the thyroid hormone metabolism in the hen's heart.In Exp3. The effects of dietary selenium and iodine on the cellular DNA damage in laying hens were examined. The activity of the CAT decreased in the serum (P<0.05) and spleen cell (P<0.05) butincreased in the liver cell (P<0.01), the activity of the GPx increased in the serum (P<0.01) but decreased in the blood lymphocytes (P<0.01) and liver cells (P<0.05), and the activity of the SOD decreased in the liver cells (P<0.01) in the iodine deficiency treatment; the activity of GPx decreased in the serum (P<0.01), blood lymphocytes (P<0.01), spleen cells (P<0.05) and liver cells (P<0.01), the activity of the CAT increased in the lymphocytes (P<0.05), the activity of the SOD decreased in the blood lymphocytes and liver cells (P<0.01) in the selenium deficiency treatment; the interaction of selenium and iodine can affect the activity of the GPx in the serum (P<0.01) and liver cells (P<0.05), the activity of the SOD (P<0.01) and CAT (P<0.05) in the blood lymphocytes and the activity of the SOD in the spleen cells (P<0.05). The deficiency of selenium and iodine in the dietary resulted in DNA damage in the blood lymphocytes, spleen and liver cells (P<0.05). A severe DNA damage (P<0.05) was observed in blood lymphocytes with iodine deficiency, compared with the selenium deficiency or the combination deficiency of selenium and iodine.In Exp4. The effects of dietary selenium and iodine on the hepatic mRNAs expression of ID-I, UCP3 and GPx-4 in laying hens were examined. The results showed t...