جستجوی مقالات مرتبط با کلیدواژه « thyroid hormones » در نشریات گروه « دامپزشکی »

On account of the importance of iodine in the synthesis of thyroid hormones, different levels of dietary iodine can affect the occurrence of ascites syndrome in broilers.

The current research aimed to investigate the effects of different sources and levels of iodine on performance, carcass traits, ascites mortality, thyroid hormones, and serum biochemical parameters of broiler chickens under cold stress condition.

This experiment was performed using 375 one-day-old male broiler chickens in a completely randomized design with five treatments, five replications, and 15 birds per replication. To induce ascites, the room temperature was reduced to 15 °C from 14 days and this temperature was maintained until the end of the period. The experimental treatments included: control treatment (basal diet with iodine at the recommended level, 1.25 ppm), basal diet + potassium iodide (KI) with iodine levels (6.25 and 3.75 ppm), and basal diet + calcium iodate [Ca(IO3)2. H2O] with iodine levels (6.25 and 3.75 ppm).

The effect of the treatments on the performance indices was not significant throughout the experiment. The lowest percentage of ascites mortality, heart weight, and triiodothyronine (T3) were observed in the treatment (6.25 ppm), which was significantly different from the control treatment (P<0.05). The lowest ratio of right ventricle to total ventricles (RV/TV) was related to potassium iodide treatment (6.25 ppm), which indicated tendency (P<0.10). Chickens receiving higher levels of iodine (6.25 ppm) had higher thyroxine than those receiving lower levels (3.75 ppm) (P<0.05) and showed a lower ratio of triiodothyronine to thyroxine compared to those (P<0.05).

The results of this experiment implied that the use of higher levels of dietary iodine (6.25 ppm), especially as potassium iodide, reduces broiler’s ascites mortality under cold stress conditions.

In poultry farms, the stresses are inevitable, therefore, it is very necessary to achieve an efficient and practical way to control and reduce its negatives effects. Thus, this study was conducted to evaluate the effects of different sources of chromium on thyroid hormones and some blood parameters of broiler chicks under physiological stress conditions. A total of 216 one day old Ross broiler chicks (male) were used in a 3 × 2 factorial arrangement with two stress conditions (no stress, stress) and three levels of additive (no Additive, 2000ppb chromium-methionine, and 2000ppb chrome-methionine mill) in a completely randomized design with 6 treatments, 3 replicates and 12 bird per each. Dexamethasone was added to the diet (1.5 mg/kg diet) during 24-18 days of age to induce physiological stress. The birds were fed with chromium diets from 18 d until the end of the experiment. Blood samples were taken at 24 and 46 days of age via brachial vein and then analyzed for blood glucose, lipids, cortisol, thyroxine (T4) and thyroid iodothyronine (T3). Physiological stress reduced the concentration of thyroid hormones, glucose, serum lipids and cortisol hormones. In stressed birds, the use of chrome methionine diet significantly reduced cholesterol of serum. Chromium supplementing diet increased thyroxine (T4) concentration. Dietary chromium methionine significantly decreased cortisol concentrations of serum. Based on the results, adding chromium ppb 2000 from various sources reduces the effects of physiological stress on thyroid hormones and cholesterol concentrations in the serum of birds under physiological stress.

The present investigation was performed to determine the effect of long-term administration of sodium selenite on the biochemical indices and concentration of thyroid hormones in calves. Sodium selenite solution was drenched at 0.1 and 0.25 mg per kg body weight for 12 weeks. Higher dose produced characteristic symptoms of selenosis whereas mild symptoms were observed with lower dose. The toxic symptoms appeared when blood selenium level was 1.68 ± 0.13 mg per ml. There was a significant (P<0.05) increase in the activities of the aspartate aminotransferase, alkaline phosphatase, blood urea nitrogen and creatinine levels in the treated animals. The repeated administration of sodium selenite resulted in a significant p-value decline in thyroxine levels on the 10th week and increase in triiodothyronine on the 8th week of treatment. The findings of the present study suggested that sodium selenite induced selenosis alters thyroid hormone levels in plasma.