Ibrahim Doaa, Shawky Mohamed, El-Sayed Kamel Asmaa, Abdelfattah-Hassan Ahmed, Taha Rahma, Khalil Samah S, Elabbasy Mohamed Tharwat, Kishawy Asmaa T Y
Department of Nutrition and Clinical Nutrition, Faculty of Veterinary Medicine, Zagazig University, Egypt.
Avian Research Center, King Faisal University, P.O. Box 400, Al-Hofuf, Al-Ahsa, 31982, Saudi Arabia.
J Therm Biol. 2025 Aug 15;132:104222. doi: 10.1016/j.jtherbio.2025.104222.
Adopting innovative nutritional strategies, such as microalgae blend supplementation, can help reduce the detrimental effects of heat stress (HS) in poultry farming. This study was designed to explore the effects of different dietary levels of microalgae blend containing nannochloropsis oculate, schizochytrium and amphora coffesformis on modulating growth performance, muscle's antioxidant status, lipid profile and the expression of heat shock proteins and sirtuins family related genes in heat-stressed chicks. A total of 250 one-day-old chicks were randomly assigned to five experimental groups, with five replicates of 10 birds each: a control group reared under normal environmental conditions and fed a basal diet; HS group exposed to heat stress and fed a basal diet; and three HS groups supplemented with a microalgae blend at 2.5, 5, and 10 g/kg of diet, respectively. A notable improvement in total growth and FCR especially was recorded in group exposed to HS and supplemented with 10 g/kg diet of microalgae blend compared to HS group. Moreover, the group exposed to HS and fortified with microalgae blend at the concentration of 10 g/kg diet showed reduced cholesterol and triacylglycerol levels, comparable to those of the control group. Notably, all heat-stressed groups supplemented with the microalgae blend showed no significant changes in blood parameters compared to the control group. In the heat-stressed group, dietary supplementation with 10 g/kg of the microalgae blend significantly reduced the levels of ALT, uric acid, AST, creatinine, corticosterone, and thyroid hormones (T3 and T4), bringing them closer to normal physiological ranges. With increasing levels of the microalgae blend, there was a marked enhancement in the activity of muscle antioxidant enzymes, including glutathione peroxidase (GSH-Px), catalase, and superoxide dismutase (SOD), along with an increase in T-AOC content, accompanied by a significant reduction in MDA levels. Notably, increasing the concentration of the microalgae blend resulted in elevated levels of n-3 PUFAs, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in the breast muscle. Relative mRNA expression levels of Hsp70, Hsp90, SIRT1, SIRT3, and SIRT7 were elevated in the heat-stressed groups; however, the group supplemented with 10 g/kg of the microalgae blend exhibited the most pronounced downregulation of these genes. In conclusion, this study underscores the potential of the microalgae blend to mitigate the adverse effects of heat stress in poultry farming via modulating antioxidant activity, upregulating expression of sirtuins family and attenuating the overexpression of heat shock proteins.
采用创新的营养策略，如添加微藻混合物，有助于减轻家禽养殖中热应激（HS）的有害影响。本研究旨在探讨不同日粮水平的包含卵形微拟球藻、裂殖壶菌和咖啡形双眉藻的微藻混合物对热应激雏鸡生长性能、肌肉抗氧化状态、血脂水平以及热休克蛋白和沉默调节蛋白家族相关基因表达的调节作用。总共250只1日龄雏鸡被随机分为五个实验组，每组10只，重复五次：一个对照组在正常环境条件下饲养并饲喂基础日粮；热应激组暴露于热应激环境并饲喂基础日粮；三个热应激组分别添加2.5、5和10克/千克日粮的微藻混合物。与热应激组相比，暴露于热应激并添加10克/千克日粮微藻混合物的组在总生长和饲料转化率方面有显著改善。此外，暴露于热应激并添加10克/千克日粮浓度微藻混合物的组胆固醇和三酰甘油水平降低，与对照组相当。值得注意的是，所有添加微藻混合物的热应激组与对照组相比血液参数无显著变化。在热应激组中，添加10克/千克微藻混合物的日粮显著降低了谷丙转氨酶、尿酸、谷草转氨酶、肌酐、皮质酮和甲状腺激素（T3和T4）的水平，使其更接近正常生理范围。随着微藻混合物水平的增加，肌肉抗氧化酶的活性显著增强，包括谷胱甘肽过氧化物酶（GSH-Px）、过氧化氢酶和超氧化物歧化酶（SOD），同时总抗氧化能力（T-AOC）含量增加，丙二醛（MDA）水平显著降低。值得注意的是，增加微藻混合物的浓度导致胸肌中n-3多不饱和脂肪酸（PUFAs）水平升高，尤其是二十碳五烯酸（EPA）和二十二碳六烯酸（DHA）。热应激组中热休克蛋白70（Hsp70）、热休克蛋白90（Hsp90）、沉默调节蛋白1（SIRT1）、沉默调节蛋白3（SIRT3）和沉默调节蛋白7（SIRT7）的相对mRNA表达水平升高；然而，添加10克/千克微藻混合物的组这些基因的下调最为明显。总之，本研究强调了微藻混合物通过调节抗氧化活性、上调沉默调节蛋白家族表达和减弱热休克蛋白的过度表达来减轻家禽养殖中热应激不利影响的潜力。
