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BACKGROUND

At present, heat stress (HS) has become a key factor that impairs broiler breeding industry, which causes growth restriction and poor meat quality of broilers. Selenium (Se) is an excellent antioxidant and plays a unique role in meat quality improvement. Recent years, nano-selenium (NanoSe) has received tremendous attention in livestock production, due to its characteristic and good antibacterial performance in vitro. Here, we developed the heat stressed-broiler model to investigate the protective effects of NanoSe on growth performance and meat quality of broilers and compare whether there are differences with that of other Se sources (Sodium selenite, SS; Selenoyeast, SeY; Selenomethionine, SeMet).

RESULTS

HS jeopardized the growth performance and caused poor meat quality of breast muscle in broilers, which were accompanied by lowered antioxidant capacity, increased glycolysis, increased anaerobic metabolism of pyruvate, mitochondrial stress and abnormal mitochondrial tricarboxylic acid (TCA) cycle. All Se sources supplementation exhibited protective effects, which increased the Se concentration and promoted the expression of selenoproteins, improved the mitochondrial homeostasis and the antioxidant capacity, and promoted the TCA cycle and the aerobic metabolism of pyruvate, thus improved the breast muscle meat quality of broilers exposed to HS. However, unlike the other three Se sources, the protective effect of NanoSe on meat quality of heat stressed-broilers was not ideal, which exhibited limited impact on the pH value, drip loss and cooking loss of the breast muscle. Compared with the other Se sources, broilers received NanoSe showed the lowest levels of slow MyHC, the highest levels of fast MyHC and glycogen, the highest mRNA levels of glycolysis-related genes (PFKM and PKM), the highest protein expression of HSP60 and CLPP, and the lowest enzyme activities of GSH-Px, citroyl synthetase (CS) and isocitrate dehydrogenase (ICD) in breast muscle. Consistent with the SS, the Se deposition in breast muscle of broilers received NanoSe was lower than that of broilers received SeY or SeMet. Besides, the regulatory efficiency of NanoSe on the expression of key selenoproteins (such as SELENOS) in breast muscle of heat stressed-broilers was also worse than that of other Se sources.

CONCLUSION

Through comparing the meat quality, Se deposition, muscle fiber type conversion, glycolysis, mitochondrial homeostasis, and mitochondrial TCA cycle-related indicators of breast muscle in heat stressed broilers, we found that the protective effects of organic Se (SeY and SeMet) are better than that of inorganic Se (SS) and NanoSe. As a new Se source, though NanoSe showed some protective effect on breast muscle meat quality of heat stressed broilers, the protective effect of NanoSe is not ideal, compared with other Se sources.

BACKGROUND

RESULTS

CONCLUSION

背景

目前，热应激（HS）已成为损害肉鸡养殖业的关键因素，它会导致肉鸡生长受限和肉质不佳。硒（Se）是一种优良的抗氧化剂，在改善肉质方面发挥着独特作用。近年来，纳米硒（NanoSe）因其特性和体外良好的抗菌性能在畜牧生产中受到了极大关注。在此，我们建立了热应激肉鸡模型，以研究纳米硒对肉鸡生长性能和肉质的保护作用，并比较其与其他硒源（亚硒酸钠，SS；硒酵母，SeY；硒代蛋氨酸，SeMet）的差异。

结果

热应激损害了肉鸡的生长性能，导致胸肌肉质不佳，同时伴随着抗氧化能力降低、糖酵解增加、丙酮酸无氧代谢增加、线粒体应激以及线粒体三羧酸（TCA）循环异常。所有硒源的补充均表现出保护作用，提高了硒浓度，促进了硒蛋白的表达，改善了线粒体稳态和抗氧化能力，促进了TCA循环以及丙酮酸的有氧代谢，从而改善了热应激肉鸡的胸肌肉质。然而，与其他三种硒源不同，纳米硒对热应激肉鸡的肉质保护作用并不理想，对胸肌的pH值、滴水损失和蒸煮损失影响有限。与其他硒源相比，并纳米硒的肉鸡胸肌中慢肌球蛋白重链（MyHC）水平最低，快肌球蛋白重链、糖原水平最高，糖酵解相关基因（PFKM和PKM）的mRNA水平最高，HSP60和CLPP的蛋白表达最高，谷胱甘肽过氧化物酶（GSH-Px）、柠檬酸合成酶（CS）和异柠檬酸脱氢酶（ICD）的酶活性最低。与亚硒酸钠一样，纳米硒组肉鸡胸肌中的硒沉积低于硒酵母或硒代蛋氨酸组肉鸡。此外，纳米硒对热应激肉鸡胸肌中关键硒蛋白（如SELENOS）表达的调节效率也低于其他硒源。