In beef heifers, body weight (BW) gain and physiological stress are important considerations for reproductive outcomes and whole herd production efficiencies. The objective of this study was to determine if dietary one-carbon metabolite (OCM) supplementation in moderate BW loss pregnant heifers alters circulating total antioxidant capacity, superoxide dismutase, and glutathione peroxidase activity. In a replicated 2 × 2 factorial, Angus-cross heifers (n = 81) were stratified by BW to gain 0.45 kg/d (CON) or lose 0.23 kg/d (RES) and receive corn carrier with OCM supplements (+OCM) or without (−OCM). The OCM supplements consisted of vitamin B12 (20 mg) and folate (320 mg) injections weekly and dietary rumen-protected methionine (7.4 g/d) and choline (44.4 g/d) from breeding (d 0) to d 63 of gestation. The four treatment groups were: CON−OCM (n = 20), CON+OCM (n = 21), RES−OCM (n = 21), and RES+OCM (n = 19). Heifers underwent estrus synchronization and were bred via artificial insemination using female sexed semen to a single sire. Pregnancy was diagnosed and fetal sex was verified on d 35 of gestation. Blood was collected and assayed for total antioxidant capacity, superoxide dismutase, and glutathione peroxidase activity on d −2 (baseline), 35, and 63 of gestation for all three replicates. Data were analyzed using the MIXED procedure of SAS with repeated measures to determine the effect of gain, supplement, day, and their two-way and three-way interactions. The gain × supplement interaction remained in all models, but other interactions were removed if P > 0.10. Replicate and heifer BW were included in the model as covariates and covariance structure was determined by lowest AIC and BIC. Statistical significance was considered at P ≤ 0.05 and tendencies at 0.05 < P ≤ 0.10. There was no BW gain × supplement interaction, or main effect of OCM supplements in total antioxidants. There was a gain × day effect (P ≤ 0.01), in which total antioxidants were increased on d 35 and further increased on d 63 in CON compared with RES treatments. There was no gain × supplement interaction, or main effect of gain or OCM supplements in superoxide dismutase and glutathione peroxidase. However, both superoxide dismutase and glutathione peroxidase were decreased (P ≤ 0.01) on d 63 compared with d 0 and 35. These data suggest that moderate BW loss reduces total antioxidant capacity in pregnant beef heifers, which could affect redox homeostasis. However, OCM supplements did not affect total antioxidant capacity, superoxide dismutase, or glutathione peroxidase. These findings are somewhat surprising considering oxidative stress has been well characterized in nutrient-restricted pregnancies, and given the interconnection between energy metabolism and one-carbon metabolism. Future research is warranted to fully elucidate the therapeutic effects of one-carbon metabolites.

中文翻译：

---

227 适度的体重减轻会降低怀孕肉牛的总抗氧化能力，而补充一碳代谢物并不能减轻这种反应


在肉牛中，体重 （BW） 增加和生理压力是繁殖结果和整个畜群生产效率的重要考虑因素。本研究的目的是确定中度 BW 损失怀孕小母牛的膳食一碳代谢物 （OCM） 补充剂是否会改变循环总抗氧化能力、超氧化物歧化酶和谷胱甘肽过氧化物酶活性。在重复的 2 × 2 因子中，安格斯杂交小母牛 （n = 81） 按 BW 分层，增加 0.45 kg/d （CON） 或减少 0.23 kg/d （RES），并接受有 OCM 补充剂 （+OCM） 或没有 （-OCM） 的玉米载体。OCM 补充剂包括每周注射维生素 B12 （20 mg） 和叶酸 （320 mg） 以及从繁殖 （d 0） 到妊娠 d 63 的日粮瘤胃保护蛋氨酸 （7.4 g/d） 和胆碱 （44.4 g/d）。四个治疗组是：CON−OCM （n = 20）、CON+OCM （n = 21）、RES−OCM （n = 21） 和 RES+OCM （n = 19）。小母牛经历了发情同步，并使用雌性性别精液通过人工授精繁殖到单个公牛。诊断怀孕并在妊娠第 35 天验证胎儿性别。对于所有三个重复，收集血液并测定妊娠 d -2 （基线） 、 35 和 63 的总抗氧化能力、超氧化物歧化酶和谷胱甘肽过氧化物酶活性。使用 SAS 的 MIXED 程序对数据进行分析，并重复测量以确定增益、补充剂、天数及其双向和三向交互作用的影响。所有模型中均保留增益×补充剂交互作用，但如果 P > 0.10，则删除其他交互作用。复制和小母牛 BW 作为协变量包含在模型中，协方差结构由最低的 AIC 和 BIC 确定。P 值为 0.05 时≤统计学显着性，趋势为 0。05 < P ≤ 0.10.没有 BW 增加×补充剂相互作用，也没有 OCM 补充剂对总抗氧化剂的主要影响。× 天效应有所增加 （P ≤ 0.01），与 RES 处理相比，CON 的总抗氧化剂在第 35 天增加，在第 63 天进一步增加。在超氧化物歧化酶和谷胱甘肽过氧化物酶中，没有增益×补充剂的相互作用，也没有增益或 OCM 补充剂的主要影响。然而，与第 0 天和第 35 天相比，第 63 天超氧化物歧化酶和谷胱甘肽过氧化物酶均降低 （P ≤ 0.01）。这些数据表明，适度的 BW 损失会降低怀孕肉小母牛的总抗氧化能力，这可能会影响氧化还原稳态。然而，OCM 补充剂不影响总抗氧化能力、超氧化物歧化酶或谷胱甘肽过氧化物酶。考虑到氧化应激在营养限制妊娠中得到了很好的表征，并且考虑到能量代谢和一碳代谢之间的相互联系，这些发现有点令人惊讶。未来的研究是必要的，以充分阐明一碳代谢物的治疗效果。