title: Thermal manipulation during late embryogenesis: Effect on body weight and temperature, thyroid hormones, and differential white blood cell counts in broiler chickens.
abstract: The effects of thermal manipulation (TM) at 38.5°C and 40°C for 6 h at embryonic day (ED) 16, 9 h at ED 17, and 12 h at ED 18 on body weight (BW) and cloacal body temperature (Tb) during the first wk and later at post-hatch d 10, 14, 21, 28, and 42 were evaluated. Furthermore, chicks' ability to cope with a thermal challenge (TC; 41°C for 6 h) at post-hatch d 14 and 42 was also evaluated. A chick's response to TC was measured by determining the cloacal body temperature; the plasma thyroid hormones (thyroxin (T4) and triiodothyronine (T3)); the packed cell volume (PCV); the heterophil (H), lymphocyte (L), monocyte, basophil, and eosinophil percentages; and the heterophil-to-lymphocyte ratios (H/L). Thermal manipulation did not affect the hatchability. However, the body weight of TM chicken was higher compared with controls at marketing age (post-hatch d 42). At post-hatch d 14 and 42, no significant changes in Tbwere observed among the different treatment groups. However, during TC at d 14 and 42, the Tbof TM chicks was lower compared with the controls. During TC, a significant increase in plasma T4and a significant decrease in plasma T3of TM chicks compared with controls were reported. Furthermore, during TC, a significant increase in the PCV and heterophil, monocyte, and H/L ratios, and a reduction in the lymphocyte percentages also were observed in TM chicks compared with the controls. Results of this study showed that chicks subjected to heat manipulation during late embryogenesis respond better to heat stress later in the growth and development period.
authors: Department of Veterinary Pathology and Public Health, Faculty of Veterinary Medicine, Jordan University of Science and Technology, P. O. Box 3030, Irbid-22110-Jordan ralrukib@just.edu.jo.
authors: R K
authors: RK
authors: Al-Rukibat
authors: Department of Basic Medical Veterinary Sciences, Faculty of Veterinary Medicine, Jordan University of Science and Technology, P. O. Box 3030, Irbid-22110-Jordan.
authors: M B
authors: MB
authors: Al-Zghoul
authors: Department of Veterinary Pathology and Public Health, Faculty of Veterinary Medicine, Jordan University of Science and Technology, P. O. Box 3030, Irbid-22110-Jordan.
authors: W M
authors: WM
authors: Hananeh
authors: Department of Veterinary Pathology and Public Health, Faculty of Veterinary Medicine, Jordan University of Science and Technology, P. O. Box 3030, Irbid-22110-Jordan.
authors: M Q
authors: MQ
authors: Al-Natour
authors: Department of Basic Medical Veterinary Sciences, Faculty of Veterinary Medicine, Jordan University of Science and Technology, P. O. Box 3030, Irbid-22110-Jordan.
authors: E A
authors: EA
authors: Abu-Basha
mesh_terms: D000818:Animals; D001833:Body Temperature Regulation; D001835:Body Weight; D002642:Chick Embryo; D002645:Chickens / Q000254:growth & development / Q000502:physiology*; D047108:Embryonic Development; D006403:Hematologic Tests / Q000662:veterinary; D007958:Leukocyte Count / Q000662:veterinary; D011897:Random Allocation; D013696:Temperature; D013963:Thyroid Hormones / Q000378:metabolism; D013997:Time Factors
chemical_list: D013963:Thyroid Hormones
keywords: broiler chicks; growth; heat stress; heterophil/lymphocyte ratio; thermal manipulation