Al Amaz Sadid, Chaudhary Ajay, Mahato Prem Lal, Jha Rajesh, Mishra Birendra
Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, University of Hawai'i at Manoa, AgSci 216, 1955 East-West Rd, Honolulu, HI, 96822, USA.
J Anim Sci Biotechnol. 2024 Jan 22;15(1):8. doi: 10.1186/s40104-023-00966-6.
High environmental temperatures induce heat stress in broiler chickens, affecting their health and production performance. Several dietary, managerial, and genetics strategies have been tested with some success in mitigating heat stress (HS) in broilers. Developing novel HS mitigation strategies for sustaining broiler production is critically needed. This study investigated the effects of pre-hatch thermal manipulation (TM) and post-hatch baicalein supplementation on growth performance and health parameters in heat-stressed broilers.
Six hundred fertile Cobb 500 eggs were incubated for 21 d. After candling on embryonic day (ED) 10, 238 eggs were thermally manipulated at 38.5 °C with 55% relative humidity (RH) from ED 12 to 18, then transferred to the hatcher (ED 19 to 21, standard temperature) and 236 eggs were incubated at a controlled temperature (37.5 °C) till hatch. After hatch, 180-day-old chicks from both groups were raised in 36 pens (n = 10 birds/pen, 6 replicates per treatment). The treatments were: 1) Control, 2) TM, 3) control heat stress (CHS), 4) thermal manipulation heat stress (TMHS), 5) control heat stress supplement (CHSS), and 6) thermal manipulation heat stress supplement (TMHSS). All birds were raised under the standard environment for 21 d, followed by chronic heat stress from d 22 to 35 (32-33 °C for 8 h) in the CHS, TMHS, CHSS, and TMHSS groups. A thermoneutral (22-24 °C) environment was maintained in the Control and TM groups. RH was constant (50% ± 5%) throughout the trial. All the data were analyzed using one-way ANOVA in R and GraphPad software at P < 0.05 and are presented as mean ± SEM. Heat stress significantly decreased (P < 0.05) the final body weight and ADG in CHS and TMHS groups compared to the other groups. Embryonic TM significantly increased (P < 0.05) the expression of heat shock protein-related genes (HSP70, HSP90, and HSPH1) and antioxidant-related genes (GPX1 and TXN). TMHS birds showed a significant increment (P < 0.05) in total cecal volatile fatty acid (VFA) concentration compared to the CHS birds. The cecal microbial analysis showed significant enrichment (P < 0.05) in alpha and beta diversity and Coprococcus in the TMHSS group.
Pre-hatch TM and post-hatch baicalein supplementation in heat-stressed birds mitigate the detrimental effects of heat stress on chickens' growth performance, upregulate favorable gene expression, increase VFA production, and promote gut health by increasing beneficial microbial communities.
高温环境会导致肉鸡产生热应激，影响其健康和生产性能。人们已经试验了多种饮食、管理和遗传策略，在减轻肉鸡热应激（HS）方面取得了一定成功。迫切需要开发新的热应激缓解策略以维持肉鸡生产。本研究调查了孵化前热调节（TM）和孵化后黄芩苷补充对热应激肉鸡生长性能和健康参数的影响。
600枚可孵化的科宝500蛋孵化21天。在胚胎期（ED）10进行照蛋后，238枚蛋从ED 12至18在38.5°C、相对湿度（RH）55%的条件下进行热调节，然后转移到孵化机（ED 19至21，标准温度），236枚蛋在可控温度（37.5°C）下孵化至出雏。出雏后，两组1日龄雏鸡饲养在36个鸡笼中（n = 10只鸡/笼，每个处理6个重复）。处理组如下：1）对照组，2）热调节组，3）对照热应激组（CHS），4）热调节热应激组（TMHS），5）对照热应激补充组（CHSS），6）热调节热应激补充组（TMHSS）。所有鸡在标准环境下饲养21天，随后CHS、TMHS、CHSS和TMHSS组从第22天至35天进行慢性热应激（32 - 33°C，8小时）。对照组和热调节组维持在热中性（22 - 24°C）环境。整个试验期间相对湿度保持恒定（50%±5%）。所有数据在R和GraphPad软件中使用单因素方差分析进行分析，P < 0.05，数据以平均值±标准误表示。与其他组相比，热应激显著降低（P < 0.05）了CHS和TMHS组的最终体重和平均日增重。胚胎期热调节显著增加（P < 0.05）了热休克蛋白相关基因（HSP70、HSP90和HSPH1）和抗氧化相关基因（GPX1和TXN）的表达。与CHS组相比，TMHS组的盲肠总挥发性脂肪酸（VFA）浓度显著增加（P < 0.05）。盲肠微生物分析显示，TMHSS组的α和β多样性以及粪球菌显著富集（P < 0.05）。
孵化前热调节和孵化后给热应激鸡补充黄芩苷可减轻热应激对鸡生长性能的有害影响，上调有利基因表达，增加VFA产生，并通过增加有益微生物群落促进肠道健康。
