Qinghai University College of Agriculture and Animal Husbandry, Xining, 810016, China.
BMC Genomics. 2024 Jun 4;25(1):557. doi: 10.1186/s12864-024-10480-2.
Reducing the levels of dietary protein is an effective nutritional approach in lowering feed cost and nitrogen emissions in ruminants. The purpose of this study was to evaluate the effects of dietary Lys/Met ratio in a low protein diet (10%, dry matter basis) on the growth performance and hepatic function (antioxidant capacity, immune status, and glycolytic activity) in Tibetan lambs. Ninety two-month-old rams with an average weight of 15.37 ± 0.92 kg were randomly assigned to LP-L (dietary Lys/Met = 1:1), LP-M (dietary Lys/Met = 2:1) and LP-H (dietary Lys/Met = 3:1) treatments. The trial was conducted over 100 d, including 10 d of adaption to the diets. Hepatic phenotypes, antioxidant capacity, immune status, glycolytic activity and gene expression profiling was detected after the conclusion of the feeding trials. The results showed that the body weight was higher in the LP-L group when compared to those on the LP-M group (P < 0.05). In addition, the activities of the catalase (CAT) and glutathione peroxidase (GSH-Px) in the LP-L group were significantly increased compared with the LP-M group (P < 0.05), while the malondialdehyde (MDA) levels in LP-H group were significantly decreased (P < 0.05). Compared with LP-H group, both hepatic glycogen (P < 0.01) and lactate dehydrogenase (LDH) (P < 0.05) were significantly elevated in LP-L group. For the LP-L group, the hepatocytes were arranged radially with the central vein in the center, and hepatic plates exhibited tight arrangement. Transcriptome analysis identified 29, 179, and 129 differentially expressed genes (DEGs) between the LP-M vs. LP-L, LP-H vs. LP-M, and LP-H vs. LP-L groups, respectively (Q-values < 0.05 and |log2Fold Change| > 1). Gene Ontology (GO) and correlation analyses showed that in the LP-L group, core genes (C1QA and JUNB) enriched in oxidoreductase activity were positively correlated with antioxidant indicators, while the MYO9A core gene enriched in the immune response was positively associated with immune indicators, and core genes enriched in molecular function (PDK3 and PDP2) were positively correlated with glycolysis indicators. In summary, low-protein diet with a low Lys/Met ratio (1:1) could reduce the hepatic oxidative stress and improve the glycolytic activity by regulating the expression of related genes of Tibetan sheep.
降低日粮蛋白质水平是降低反刍动物饲料成本和氮排放的有效营养措施。本研究旨在评估低蛋白日粮（干物质基础 10%）中不同赖氨酸/蛋氨酸（Lys/Met）比例对藏羊生长性能和肝功能（抗氧化能力、免疫状态和糖酵解活性）的影响。选择 92 月龄、平均体重为 15.37±0.92kg 的公绵羊，随机分为 LP-L（日粮 Lys/Met=1:1）、LP-M（日粮 Lys/Met=2:1）和 LP-H（日粮 Lys/Met=3:1）组。试验持续 100d，包括 10d 的适应期。在饲养试验结束后，检测了肝脏表型、抗氧化能力、免疫状态、糖酵解活性和基因表达谱。结果表明，与 LP-M 组相比，LP-L 组绵羊体重更高（P<0.05）。此外，与 LP-M 组相比，LP-L 组绵羊的过氧化氢酶（CAT）和谷胱甘肽过氧化物酶（GSH-Px）活性显著升高（P<0.05），而 LP-H 组的丙二醛（MDA）水平显著降低（P<0.05）。与 LP-H 组相比，LP-L 组绵羊肝糖原（P<0.01）和乳酸脱氢酶（LDH）（P<0.05）水平显著升高。LP-L 组的肝细胞呈放射状排列，中央静脉位于中心，肝板排列紧密。转录组分析表明，LP-M 与 LP-L、LP-H 与 LP-M、LP-H 与 LP-L 三组间分别有 29、179 和 129 个差异表达基因（DEGs）（Q 值<0.05，|log2Fold Change|>1）。基因本体（GO）和相关性分析表明，在 LP-L 组中，富集在氧化还原酶活性的核心基因（C1QA 和 JUNB）与抗氧化指标呈正相关，而富集在免疫反应的 MYO9A 核心基因与免疫指标呈正相关，富集在分子功能的核心基因（PDK3 和 PDP2）与糖酵解指标呈正相关。综上所述，低蛋白日粮（Lys/Met 比 1:1）可通过调节藏羊相关基因的表达来降低肝脏氧化应激，提高糖酵解活性。
