חיפוש מתקדם
Luger, D., Department of Poultry Sciences, Institute of Animal Science, ARO, the Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel
Shinder, D., Department of Poultry Sciences, Institute of Animal Science, ARO, the Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel
Yahav, S., Department of Poultry Sciences, Institute of Animal Science, ARO, the Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel
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 Ta. 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 Ta and supplementation of a pellet-form diet. Exogenous thyroxin T4 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 T4 (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 T4-treated chickens, although the T4 concentration reached pharmacological levels, the triiodothyronine T3 concentration remained within physiological levels, whereas T3 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 T4 and T3 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. © 2002 Elsevier Science (USA). All rights reserved.
פותח על ידי קלירמאש פתרונות בע"מ -
הספר "אוצר וולקני"
אודות
תנאי שימוש
Hyper- or hypothyroidism: Its association with the development of ascites syndrome in fast-growing chickens
127
Luger, D., Department of Poultry Sciences, Institute of Animal Science, ARO, the Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel
Shinder, D., Department of Poultry Sciences, Institute of Animal Science, ARO, the Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel
Yahav, S., Department of Poultry Sciences, Institute of Animal Science, ARO, the Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel
Hyper- or hypothyroidism: Its association with the development of ascites syndrome in fast-growing chickens
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 Ta. 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 Ta and supplementation of a pellet-form diet. Exogenous thyroxin T4 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 T4 (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 T4-treated chickens, although the T4 concentration reached pharmacological levels, the triiodothyronine T3 concentration remained within physiological levels, whereas T3 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 T4 and T3 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. © 2002 Elsevier Science (USA). All rights reserved.
Scientific Publication
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