We hypothesised that supplementation of green tea extract (GTE) in dairy cows during the transition period can attenuate proinflammatory conditions and prevent endoplasmic reticulum (ER) stress in the liver of these cows. Thirty Holstein cows with an average parity of 3.06 (± 1.31, SD) were divided into a control group and a group that received a daily amount of 10 g of GTE from d 7 before the calving day and a daily amount of 20 g of GTE from the day of calving until d 7 of lactation. Cows supplemented with GTE did not show differences in energy intake or milk yield in weeks 2–7 of lactation. However, these cows had a lower milk fat concentration and a lower energy corrected milk yield than the control cows and showed a trend of improved energy balance. The relative mRNA concentrations of proinflammatory genes, genes involved in the acute phase reaction and antioxidant genes in the liver in weeks 1, 4 and 7 of lactation were not different between the two groups of cows. The concentrations of α-tocopherol and the Trolox equivalent antioxidant capacity in plasma were not different between the two groups. However, the group supplemented with GTE showed significant reductions of some genes of the unfolded protein response (UPR) in week 1 and a trend of lower liver triacylglycerol (TAG) concentrations in the liver compared to the control group. This study shows that supplementation of GTE in dairy cows lowers the fat concentration in the milk but overall has no effect on the expression of inflammatory genes and the antioxidative status in dairy cows during early lactation. The finding of reduced mRNA levels of genes involved in the UPR at week 1, however, supports other results showing that supplementation of polyphenols could prevent the development of ER stress in the liver of cows during early lactation. The finding of a tendency towards a reduced TAG concentration in the liver of cows supplemented with GTE might be due to an improved energy balance in these cows.

中文翻译：

---

补充绿茶提取物对围产期奶牛产奶性能及肝脏应激反应基因表达的影响。

我们假设奶牛在过渡期补充绿茶提取物 (GTE) 可以减轻这些奶牛肝脏的促炎状况并预防内质网 (ER) 应激。将 30 头平均胎次为 3.06（±1.31，SD）的荷斯坦奶牛分为对照组和从产犊前第 7 天开始每天接受 10 克 GTE 和每天 20 克 GTE 的组从产犊之日到泌乳第 7 天。补充 GTE 的奶牛在泌乳第 2-7 周没有表现出能量摄入或产奶量的差异。然而，与对照奶牛相比，这些奶牛的乳脂浓度和能量校正奶产量较低，并显示出能量平衡改善的趋势。促炎基因的相对mRNA浓度，两组奶牛在泌乳第 1、4 和 7 周参与急性期反应的基因和肝脏中的抗氧化基因没有差异。血浆中α-生育酚浓度和Trolox等效抗氧化能力在两组之间没有差异。然而，与对照组相比，补充 GTE 的组在第 1 周显示未折叠蛋白反应 (UPR) 的一些基因显着降低，并且肝脏中的肝脏三酰基甘油 (TAG) 浓度呈降低趋势。本研究表明，奶牛补充 GTE 可降低牛奶中的脂肪浓度，但总体上对泌乳早期奶牛炎症基因的表达和抗氧化状态没有影响。然而，在第 1 周发现参与 UPR 的基因的 mRNA 水平降低，支持其他结果表明补充多酚可以防止泌乳早期奶牛肝脏中 ER 应激的发展。发现补充 GTE 的奶牛肝脏中 TAG 浓度降低的趋势可能是由于这些奶牛的能量平衡得到改善。