propylthiouracil and Poultry-Diseases

1. The present study was conducted to examine the effects of α-lipoic acid on hypothyroidism-induced negative growth performance and whether α-lipoic acid alleviates acute heat stress in relation to hypothyroid status. 2. Female broiler chickens (14 d-old) were fed diets supplemented with α-lipoic acid (100 mg/kg) and an antithyroid substance, propylthiouracil (200 mg/kg), for 20 d under thermoneutral conditions (25°C). At 42 d of age, chickens were exposed to a high ambient temperature (36°C, 60% RH) for 4 h. 3. Under the thermoneutral condition, propylthiouracil administration decreased feed efficiency and concomitantly increased adipose tissue and thyroid gland weights. Plasma nonesterified fatty acids and triacylglycerol were also increased by propylthiouracil administration. However, α-lipoic acid supplementation did not affect the hypothyroidism-induced effects. 4. In hypothyroid chickens, the rise in respiratory rate induced by heat exposure was greatly inhibited by α-lipoic acid administration at 1 h, but this effect had disappeared at 4 h. In addition, a similar inhibitory effect on the concentrations of plasma nonesterified fatty acids was subsequently observed at 4 h. 5. Therefore, the present study suggested that α-lipoic acid alleviates acute heat stress if chickens are in a hypothyroid status.

Topics: Animal Feed; Animals; Body Weight; Chickens; Diet; Dietary Supplements; Fatty Acids, Nonesterified; Female; Hot Temperature; Hypothyroidism; Poultry Diseases; Propylthiouracil; Stress, Physiological; Thioctic Acid

A hypothesis was tested that providing the breeder hens with exogenous thyroxine (T(4)) would help their offspring to better survive the ascites-inducing condition during the growing period. In total, 132 broiler breeder hens were randomly assigned to one of 3 treatments: control (CON), hypothyroid [HYPO; 6-N-propyl-2-thiouracil (PTU)-treated], and hyperthyroid (HYPER; T(4)-treated). The hens were artificially inseminated, and the hatching eggs (n = 1,320) were incubated. No eggs in the HYPO group hatched. The 1-d-old male chicks (n = 288) from other groups were reared for 42 d under standard or low ambient temperature to induce ascites. Blood samples were drawn from the hens, embryos, and broilers for determination of T(4) and triiodothyronine (T(3)). The hematocrit was also determined in broilers. The PTU-treated hens had an increased BW along with lower plasma T(3) and T(4) concentrations. Plasma T(4) was higher in the HYPER hens compared with CON hens, but T(3) concentration was not different between these groups. The fertility rate was not affected by either hypo- or hyperthyroidism. The embryos in the HYPO group had lower plasma T(3) and T(4) concentrations at d 18 of embryonic development and internal pipping. Higher plasma T(4) was recorded in the HYPER birds at internal pipping, although plasma T(3) concentration was not affected at this stage. Maternal hyperthyroidism decreased the overall incidence of ascites in the cold-exposed chickens (10.0 vs. 33.4% for HYPER and CON groups, respectively). Although the effect of maternal PTU or T(4) treatment on plasma thyroid hormones and on the right ventricle-to-total ventricular weight ratio in the broilers was not significant, the cold-exposed healthy CON chicks showed higher hematocrit values, compared with the HYPER birds. It was concluded that maternal hyperthyroidism could decrease the incidence of cold-induced ascites in broiler chickens; however, probable causal mechanisms remain to be elucidated.

Topics: Animals; Ascites; Chickens; Cold Temperature; Female; Hyperthyroidism; Hypothyroidism; Male; Poultry Diseases; Propylthiouracil; Thyroxine; Weight Gain

The ascites syndrome in broiler chickens is attributed to the progress in genetic selection for rapid growth, coupled with the metabolic burden imposed by exposure to a relatively low-ambient temperature (T(a)). The syndrome is mainly characterized by hematocrit elevation, decline in blood oxygen saturation, accumulation of fluid in the abdominal cavity, and finally, death. Ascitic chickens have demonstrated hypothyroidism coupled with a marked stress response (high corticosterone concentration) and reduction in the hemoglobin content. The objective of the present study was to examine the role of thyroid and corticosterone hormones in the development of the syndrome. Ascites was induced by exposure to a gradually declining T(a) and supplementation of a pellet-form diet. Exogenous thyroxin (T(4)) and propylthiouracil (PTU) (in Experiments 1 and 2, respectively) were supplemented in drinking water to induce hyper- or hypothyroidism, respectively. Ascites syndrome was developed in 21.5% and 23% of the birds exposed to ascites-induced conditions (Exps. 1 and 2, respectively). Excess T(4) (Exp. 1) significantly reduced the percentage of ascites (down to 7%), whereas PTU (Exp. 2) significantly increased the appearance of the syndrome (35%). In the T(4)-treated chickens, although the T(4) concentration reached pharmacological levels, the triiodothyronine (T(3)) concentration remained within physiological levels, whereas T(3) in the ascitic birds exhibited a reduction pattern similar to that observed in the ascitic non-supplemented ones. In the PTU-treated chickens, however, both ascitic and non-ascitic birds demonstrated significant reductions in both T(4) and T(3) concentrations. In both experiments, ascitic chickens exhibited a considerable stress response, characterized by a significant and persisted elevation in plasma corticosterone concentration, which was in accordance with a similar elevation of hematocrit, and the PTU-treated non-ascitic birds exhibited a similar stress response. At 5 weeks of age, ascitic birds and the PTU-treated non-ascitic ones exhibited significant reductions in the hemoglobin content of their red blood cells. It may be concluded that deficiency in the thyroid hormones and elevated corticosterone may play a key deleterious role in the development of the ascites syndrome.

Topics: Aging; Animals; Ascites; Chickens; Corticosterone; Hematocrit; Hemoglobins; Hyperthyroidism; Hypothyroidism; Male; Poultry Diseases; Propylthiouracil; Syndrome; Thyroxine; Triiodothyronine

A study was conducted to determine the effects of transient hypothyroidism induced by propylthiouracil (PTU) on termination of photorefractoriness and reinitiation of lay in turkey breeder hens. The PTU was given for 6- or 8-wk periods via the feed and at various doses to yearling hens that had been continuously exposed to long photoperiods [16 h light (L):8 h dark (D)] for at least 25 wk. There was a dose-dependent cessation of lay as well as deletion of thyroxine (T4) and triiodothyronine (T3) during the treatment period. Hens receiving 0.1% PTU or more had little or no circulating thyroid hormones after 2 wk of treatment. Furthermore, resumption of a normal rate and duration of egg laying occurred following withdrawal of the PTU, without any changes in photoperiod. However, this effect only occurred in those hens that had received PTU doses of 0.1% or more and only when the treatment had been given for greater than 6 wk. The resumption of normal levels of egg laying occurred in the absence of a typical preceding molt. Body weights, livability, and fertility and hatchability of eggs from these hens were similar to those of controls. Clearly, turkey hens can be effectively recycled by pharmacological manipulation of the thyroid gland and the results are supportive of thyroid hormone(s) involvement in maintaining photorefractoriness in turkey hens.

Topics: Animals; Antithyroid Agents; Body Weight; Dose-Response Relationship, Drug; Eating; Female; Fertility; Hypothyroidism; Oviposition; Photoperiod; Poultry Diseases; Propylthiouracil; Thyroid Gland; Thyroxine; Time Factors; Triiodothyronine; Turkeys

1. Four experiments were conducted to determine if dietary ascorbic acid (AA) affects body weight gain, food intake, organ weights, plasma cholesterol concentration, and ascorbic acid concentration in the plasma and liver of growing male broilers treated with an antithyroidal agent, propylthiouracil (PTU). 2. In the first experiment, 15 mg AA was administered daily into the crop of chicks fed on a diet supplemented with or without PTU (500 mg/kg). Administration of AA reduced plasma cholesterol concentrations in the PTU-treated chicks. 3. In the other three experiments, chicks were given the basal diet or an AA-containing (3 g/kg) diet supplemented with or without PTU (250 mg or 500 mg/kg). Feeding AA partly prevented the decreases in body weight gain, gain:food ratio and weights of the bursa of Fabricius and thymus in chicks fed on the 250 mg/kg PTU diet, and also prevented the increase in plasma cholesterol concentrations in chicks fed on the PTU diet. 4. These results suggest that AA improves the performance of chicks with experimentally induced hypothyroidism.

Topics: Adrenal Glands; Animals; Ascorbic Acid; Bursa of Fabricius; Chickens; Cholesterol; Eating; Hypothyroidism; Liver; Male; Organ Size; Poultry Diseases; Propylthiouracil; Spleen; Thyroid Gland; Weight Gain

The effect of diisopropyl 1,3-dithiolan-2-ylidenemalonate (NKK-100) on experimental fatty livers was investigated in chicks administered an antithyroid agent plus synthetic estrogen or in estrogenized, starved-refed chicks. NKK-100 was added at levels of 250, 500, 1000, and 1500 mg/kg diet. Liver weight was significantly decreased by administration of NKK-100 at 1500 mg/kg diet in the estrogen-administered chicks. Liver lipid content and liver lipid deposition were significantly and inversely decreased with increasing NKK-100 concentration in the diet in the estrogen administered chicks. Plasma transaminase activity, which was elevated by the estrogen administration, was reduced by the administration of NKK-100. These results suggest that NKK-100 may be of value in preventing fatty livers in poultry.

Topics: Animals; Aspartate Aminotransferases; Body Weight; Chickens; Dienestrol; Estradiol; Fatty Liver; Lipid Metabolism; Liver; Male; Organ Size; Poultry Diseases; Propylthiouracil; Thiophenes

1. Hepatic lipid content, lipogenic enzyme activity and plasma lipid concentration were measured in chicks reared at 21 degrees or 34 degrees C and after thyroxine (T4), thiouracil (TU), propylthiouracil (PTU), dienestrol diacetate (DD) or PTU with DD had been given for 14 d. 2. At 34 degrees C there was a significant increase in the total liver lipid and triglyceride content. 3. Injections of T4 decreased liver lipid content whereas it was increased by feeding PTU or DD. The effects of PTU were more pronounced at 21 degrees C while those of DD were more pronounced at 34 degrees C. 4. There were significant interactions between temperature, thyroid status and synthetic oestrogen treatments on total lipid and triglyceride content of the liver. Fatty liver with marked steatosis could be produced through synergic actions of PTU and DD in chicks maintained at 21 degrees C.

Topics: Animals; Chickens; Dienestrol; Estradiol Congeners; Fatty Liver; Lipid Metabolism; Liver; Male; Poultry Diseases; Propylthiouracil; Temperature; Thiouracil; Thyroid Gland; Thyroxine; Triglycerides