Zaboli Gholam-Reza, Rahimi Shaban, Shariatmadari Farid, Torshizi Mohammad Amir Karimi, Baghbanzadeh Ali, Mehri Mehran
Department of Poultry Science, Faculty of Agriculture, Tarbiat Modares University, PO Box 14115-336, Tehran.
Department of Poultry Science, Faculty of Agriculture, Tarbiat Modares University, PO Box 14115-336, Tehran
Poult Sci. 2017 Feb 1;96(2):478-485. doi: 10.3382/ps/pew344. Epub 2016 Oct 6.
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.
本研究的目的是评估孵化前后热调控（TM）对育肥期（34±2°C，每天6小时）暴露于慢性热应激（CHS）的雄性肉鸡耐热性的影响。700枚罗斯308种蛋被分为以下几组：1）对照组，在标准条件下孵化和饲养；2）孵化前处理组（PRE），种蛋在胚胎期第7至16天暴露于39.5°C和65%相对湿度环境中12小时，孵化后的雏鸡在标准条件下饲养；3和4）3日龄时进行孵化后热调控（PO3）和5日龄时进行孵化后热调控（PO5），它们的孵化条件与对照组相同，分别在3日龄和5日龄时暴露于36至38°C环境中24小时。与对照组相比，PRE组的热调控导致出雏时间延迟（6小时）以及体重下降（P = 0.02）。热调控使面部表面温度（FST）在28日龄前显著降低（P < 0.02），但在慢性热应激期间不显著。PO3和PO5组在14日龄时体重增加受到抑制（P = 0.007），并在28日龄时得到补偿。然而，与对照组相比，热调控在慢性热应激第一周导致更高的体重增加（P = 0.000）、更低的料重比（P = 0.03）和死亡率。与对照组相比，经过热调控处理的鸡的欧洲生产效率指数更高（P = 0.01）。热调控降低了尿酸、总蛋白、T3和T4的血液浓度，其中PO3和PO5处理组的甲状腺激素降低幅度比其他组更大。在PRE组中，鸡的腹部脂肪垫比对照组小（P = 0.0001）。热调控组的心脏相对重量降低（P = 0.001）。研究得出结论，热调控可能通过改变肉鸡的生理参数，特别是在慢性热应激的第一周，诱导生长中的肉鸡产生耐热性。
