Center of Excellence For Poultry Science, University of Arkansas, Fayetteville 72701, USA.
Clinical Research, Ayurvet Limited, Baddi, Himachal Pradesh 173205, India.
Poult Sci. 2021 Mar;100(3):100963. doi: 10.1016/j.psj.2020.12.060. Epub 2020 Dec 25.
Diets enriched with phytogenic feed additives (PFA) such as AV/HGP/16 premix (AVHGP), Superliv concentrate premix (SCP), and bacteriostatic herbal growth promotor (BHGP) with essential oils have been shown to improve feed efficiency (FE) in broilers. This FE improvement was achieved via modulation of hypothalamic neuropeptides, which results despite feed intake reduction, in increased breast yield without changes in body weight compared to the control group. To gain further insights into the mode of action of these PFA, the present study aimed to determine the potential involvement of signaling pathways associated with lipid and protein metabolism. One day-old male Cobb 500 chicks were randomly assigned into 1 of 4 treatments, comprising 8 replicates per treatment in a completely randomized design. The dietary treatments included a basal diet (control) or 0.55 g/kg diet of AVHGP, SCP, or BHGP. The birds had ad libitum access to water and feed. On day 35, after blood sampling, the liver, abdominal adipose tissue (AT), and breast muscle samples were collected. The levels of phosphorylated mechanistic target of rapamycin (mTOR) as well as its levels of mRNA and those of its downstream mediator RPS6B1 were significantly upregulated in the muscle of the PFA-fed groups compared with the control group. In the liver, the phosphorylated levels of acetyl-CoA carboxylase alpha at Ser79, the rate-limiting enzyme in fat synthesis, was significantly induced in the PFA-fed groups compared with the control group, indicating a lower hepatic lipogenesis. The hepatic expression of hepatic triglyceride lipase (LIPC) and adipose triglyceride lipase (ATGL) was significantly upregulated in the AVHGP-fed group compared with the control group. These hepatic changes were accompanied by a significant downregulation of hepatic sterol regulatory element-binding protein cleavage-activating protein in all the PFA groups and an upregulation of peroxisome proliferator-activated receptor alpha and gamma in the SCP-fed compared with the control group. In the AT, the mRNA abundances of ATGL and LIPC were significantly increased in both SCP- and BHGP-fed birds compared with the control group. Together these data indicate that PFA improve FE via modulation of muscle mTOR pathway and hepatic lipolytic/lipogenic programs, thus, favoring muscle protein synthesis and lowering hepatic lipogenesis.
日粮中添加植物源饲料添加剂（PFA），如 AV/HGP/16 预混料（AVHGP）、Superliv 浓缩预混料（SCP）和含精油的抑菌草本生长促进剂（BHGP），已被证明可提高肉鸡的饲料效率（FE）。这种 FE 的提高是通过调节下丘脑神经肽实现的，尽管采食量减少，但与对照组相比，产肉量增加，而体重没有变化。为了更深入地了解这些 PFA 的作用机制，本研究旨在确定与脂质和蛋白质代谢相关的信号通路的潜在参与。将 1 日龄雄性 Cobb 500 小鸡随机分为 4 个处理组，每个处理组 8 个重复，完全随机设计。日粮处理包括基础日粮（对照组）或日粮中添加 0.55 g/kg 的 AVHGP、SCP 或 BHGP。鸡可自由饮水和采食。第 35 天，采血后采集肝脏、腹部脂肪组织（AT）和胸肌组织。与对照组相比，PFA 组肌肉中磷酸化雷帕霉素靶蛋白（mTOR）及其下游介质 RPS6B1 的 mRNA 和蛋白水平显著上调。在肝脏中，脂肪合成限速酶乙酰辅酶 A 羧化酶 alpha 在丝氨酸 79 位的磷酸化水平在 PFA 组中显著高于对照组，表明肝内脂肪生成减少。与对照组相比，AVHGP 组肝组织中肝甘油三酯脂肪酶（LIPC）和脂肪甘油三酯脂肪酶（ATGL）的表达显著上调。这些肝内变化伴随着所有 PFA 组肝固醇调节元件结合蛋白裂解激活蛋白的显著下调和 SCP 组过氧化物酶体增殖物激活受体 alpha 和 gamma 的上调与对照组相比。在 AT 中，与对照组相比，SCP 和 BHGP 组的 ATGL 和 LIPC mRNA 丰度均显著增加。这些数据表明，PFA 通过调节肌肉 mTOR 途径和肝脂解/生脂程序来提高 FE，从而促进肌肉蛋白质合成和降低肝内脂肪生成。
