Molecular Physiology Laboratory, Division of Avian Physiology and Reproduction, ICAR-Central Avian Research Institute, Izatnagar, 243122, Uttar Pradesh, India.
Molecular Physiology Laboratory, Division of Avian Physiology and Reproduction, ICAR-Central Avian Research Institute, Izatnagar, 243122, Uttar Pradesh, India.
J Therm Biol. 2021 Apr;97:102840. doi: 10.1016/j.jtherbio.2021.102840. Epub 2021 Jan 20.
Physiological determinants of different body weight (BW) broiler chickens under heat stressed conditions were investigated to compare the performance at market age considering medium body weight group as standard. At 5 weeks, broilers were categorized randomly into 3 treatments (N = 24 per group) as high (HBW) (>1050 g), medium (MBW) (900-1050 g) and low (LBW) (<900 g) followed by simultaneous exposure to normal and heat stress (HS) conditions at 40 ± 1 °C and 45 ± 5% RH for 4 h/day for a period of 7 days (D) and sample collection was employed at D0, D3 and D7. Physiological and stress responses, haematological and biochemical profile, intestinal gross and histological aspects were estimated using standard protocols. Heart rate and mean arterial blood pressure were significantly (P = 0.000) higher in HBW broilers followed by low and medium ones. Heat stress exposure indicated significant (P = 0.000) increase in heart rate, arterial blood pressure, respiration rate and comb temperature while cloacal temperature remained unaffected. Lymphocytes, eosinophils, total red blood cell count, haemoglobin, and haematocrit were reduced (P = 0.000) whereas mean corpuscular volume and mean corpuscular hemoglobin, heterophil count and heterophil to lymphocyte ratio were increased (P = 0.000) in response to HS. Circulating corticosterone and tri-iodothyronine concentrations showed inverse relationship with respect to BW variation and HS duration respectively with significant interaction (P = 0.000). Higher protein in LBW was observed on D3. Serum triglycerides remained unaffected till D3 exposure but significantly (P = 0.017) reduced on D7 with lowest content in HBW group. Serum alkaline phosphatase increased in LBW group with significant heat stress interaction (P = 0.000) on D3. HS reduced villi length and crypt depth; but their corresponding ratio increased. In conclusion, HBW broilers are more affected than MBW or LBW groups. This study established interactive roles of BW and HS on physiological responses in broilers.
本研究旨在探讨热应激条件下不同体重（BW）肉鸡的生理决定因素，以比较在考虑中等体重组为标准的上市年龄时的表现。在 5 周龄时，肉鸡被随机分为 3 个处理组（每组 24 只），分别为高体重（HBW）组（>1050g）、中体重（MBW）组（900-1050g）和低体重（LBW）组（<900g），然后同时在 40±1°C 和 45±5%相对湿度下暴露于正常和热应激（HS）条件下 4 小时/天，持续 7 天（D），并在 D0、D3 和 D7 进行样品采集。使用标准方案评估生理和应激反应、血液学和生化谱、肠道大体和组织学方面。心率和平均动脉血压在 HBW 肉鸡中显著（P=0.000）升高，其次是低体重和中体重肉鸡。热应激暴露导致心率、动脉血压、呼吸率和鸡冠温度显著（P=0.000）升高，而直肠温度不受影响。淋巴细胞、嗜酸性粒细胞、总红细胞计数、血红蛋白和血细胞比容降低（P=0.000），而平均红细胞体积、平均红细胞血红蛋白、异嗜性粒细胞计数和异嗜性粒细胞与淋巴细胞比值升高（P=0.000），以应对 HS。循环皮质酮和三碘甲状腺原氨酸浓度与 BW 变化和 HS 持续时间呈反比关系，具有显著的相互作用（P=0.000）。LBW 在 D3 时观察到更高的蛋白质含量。血清甘油三酯在 D3 暴露前不受影响，但在 D7 时显著（P=0.017）降低，HBW 组含量最低。血清碱性磷酸酶在 LBW 组增加，具有显著的热应激相互作用（P=0.000）在 D3。HS 降低了绒毛长度和隐窝深度；但其相应的比例增加。总之，HBW 肉鸡比 MBW 或 LBW 组受影响更大。本研究确定了 BW 和 HS 对肉鸡生理反应的相互作用。
