title: Thermal manipulation during Pre and Post-Hatch on thermotolerance of male broiler chickens exposed to chronic heat stress.
abstract: The aim of this study was to evaluate the effects of thermal manipulation (TM) during pre and post-hatch periods on thermotolerance of male broiler chickens exposed to chronic heat stress (CHS) during the finisher phase (34 ± 2°C, 6 h/day). Seven hundred fertile eggs of Ross 308 were assigned to the following groups: 1) control group incubated and housed in standard conditions, 2) pre-hatch treatment (PRE), the eggs were exposed to 39.5°C and 65% RH for 12 h, d from embryonic d 7 to 16 and after hatching the chicks where housed in standard conditions; 3 and 4) post-hatch TM at d 3 (PO3) and post-hatch TM at d 5 (PO5), which had the same incubation conditions as control and exposed to 36 to 38°C for 24 h at 3 and 5 days of age, respectively. TM in PRE group resulted in delay in the hatch time (6 h) along with reduction in body weight compared to control (P = 0.02). TM caused a significant reduction of facial surface temperature (FST) until d 28 (P < 0.02), but not significant during CHS. Body weight gain was suppressed in PO3 and PO5 groups at d 14 (P = 0.007) and compensated at d 28. However, TM led to higher BWG (P = 0.000) but lower FCR (P = 0.03) and mortality at the first week of CHS compared to control. European production efficiency index was higher in TM-treated chickens compared to control (P = 0.01). TM reduced the blood concentration of uric acid, total protein, T3, and T4 in which thyroid hormones in PO3 and PO5 treatments showed more reduction rather than other groups. In PRE group, chickens had lower abdominal fat pad than control (P = 0.0001). The relative weight of heart was decreased in TM groups (P = 0.001). It was concluded that TM may induce thermotolerance in growing broilers, possibly through the modification of physiological parameters of broilers especially during the first week of CHS.
authors.affiliation: Department of Poultry Science, Faculty of Agriculture, Tarbiat Modares University, PO Box 14115-336, Tehran.
authors.forename: Gholam-Reza
authors.initials: GR
authors.lastname: Zaboli
authors.affiliation: Department of Poultry Science, Faculty of Agriculture, Tarbiat Modares University, PO Box 14115-336, Tehran rahimi_s@modares.ac.ir.
authors.forename: Shaban
authors.initials: S
authors.lastname: Rahimi
authors.affiliation: Department of Poultry Science, Faculty of Agriculture, Tarbiat Modares University, PO Box 14115-336, Tehran.
authors.forename: Farid
authors.initials: F
authors.lastname: Shariatmadari
authors.affiliation: Department of Poultry Science, Faculty of Agriculture, Tarbiat Modares University, PO Box 14115-336, Tehran.
authors.forename: Mohammad Amir Karimi
authors.initials: MA
authors.lastname: Torshizi
authors.affiliation: Section of Physiology, Department of Basic Sciences, Faculty of Veterinary Medicine, University of Tehran, PO Box 14155-6453, Tehran, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Baghbanzadeh
authors.affiliation: Department of Animal Sciences, Faculty of Agriculture, University of Zabol, PO Box 98661-5538, Iran.
authors.forename: Mehran
authors.initials: M
authors.lastname: Mehri
mesh_terms: D000818:Animals; D001774:Blood Chemical Analysis / Q000662:veterinary; D001823:Body Composition; D001831:Body Temperature; D002642:Chick Embryo / Q000502:physiology; D002645:Chickens / Q000097:blood / Q000254:growth & development / Q000502:physiology*; D003345:Corticosterone / Q000097:blood; D018869:Heat-Shock Response; D006358:Hot Temperature / Q000009:adverse effects*; D008297:Male; D011897:Random Allocation; D000071436:Thermotolerance; D013963:Thyroid Hormones / Q000097:blood
chemical_list: D013963:Thyroid Hormones; D003345:Corticosterone
keywords: broiler; chronic heat stress; thermal manipulation; thermotolerance