Sixty nonpregnant, nulliparous Rambouillet ewes (51 ± 1.4 kg initial body weight) were used in a completely randomized design to determine 1) if rumen-protected l-Arg (RP-ARG) supplementation would increase serum concentrations of amino acids resulting from Arg supplementation and metabolism, and decrease serum concentrations of amino acids that compete with Arg for transporters, 2) if RP-ARG supplementation would alter carotid artery hemodynamics, and 3) the most effective oral dose of RP-ARG to positively increase both circulating amino acids and improve peripheral tissue blood perfusion as measured by carotid hemodynamics. Ewes were penned individually in a temperature-controlled facility. Ewes were randomly assigned to one of four treatments: a control group that received no supplemental Arg (CON; 50 g of finely ground corn, only), or Arg-supplemented groups that received 90 (90), 180 (180), or 360 (360) mg RP-ARG·kg BW⁻¹·d⁻¹ mixed in 50 g of finely ground corn. Supplements were administered once daily for 14 d and fully consumed before the delivery of a total pelleted diet at 0630 and 1830 hours daily. Baseline and final blood samples were collected at days 0 (before treatment initiation) and 15, respectively. Doppler ultrasound was used to assess carotid arterial hemodynamics at 0600 hours on days 0 (before treatment initiation), 5, 8, 12, and 15. After 14 d of supplementation, ewes fed 180 had greater Arg (P = 0.05) and Orn (P = 0.05) and tended (P = 0.08) to have greater Asp in serum than ewes fed 90, and for these amino acids, ewes fed 180 were similar (P ≥ 0.16) compared with ewes fed 360. All supplemented ewes (90, 180, and 360) had a negative change (P = 0.02) from baseline when normalized to CON for the pulsatility and resistance indices, which indicate greater distal tissue blood perfusion and lower vascular resistance of blood flow, respectively. Additionally, there were quadratic responses for the pulsatility and resistance indices (P = 0.03 and 0.01, respectively) where ewes fed 180 had the greatest change from baseline when normalized to CON. Results indicate that Arg supplementation increased serum amino acid concentrations and improved peripheral tissue blood perfusion. The 180 mg·kg BW⁻¹·d⁻¹ RP-ARG dose was determined to be the optimal dose for nonpregnant, nulliparous Rambouillet ewes.

中文翻译：

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羔羊瘤胃保护的精氨酸：对循环血清氨基酸和颈动脉血流动力学的影响。

在完全随机的设计中使用60例未怀孕的，未产卵的Rambouillet母羊（初始体重51±1.4 kg）来确定1）瘤胃保护的l-Arg（RP-ARG）补充剂是否会增加Arg补充剂产生的氨基酸的血清浓度和代谢，并降低与Arg竞争转运蛋白的氨基酸的血清浓度； 2）补充RP-ARG是否会改变颈动脉血流动力学，以及3）最有效的口服RP-ARG剂量以积极增加循环中的氨基酸和改善通过颈动脉血流动力学测量的外周组织血液灌注。母羊在温度受控的设施中单独悬挂。将母羊随机分配至以下四种治疗方法之一：对照组，未接受任何补充精氨酸（CON ; 仅50克细磨玉米）或补充90（90），180（180）或360（360）毫克RP-ARG·kg BW ^-1 ·d ^-1的Arg补充组加入50 g玉米中玉米粉。补充剂每天给药一次，持续14天，并在每天的0630和1830小时分娩全部颗粒状饮食之前将其完全消耗掉。在第0天（治疗开始前）和第15天分别收集基线和最终血样。多普勒超声用于评估第0天（治疗开始前），5、8、12和15天0600小时的颈动脉血流动力学。补充14天后，喂食180头母羊的Arg（P = 0.05）和Orn（P= 0.05）并倾向于（P = 0.08）具有更大的Asp血清比母羊饲喂90，以及用于这些的氨基酸，饲喂母羊180是相似的（P与母羊相比≥0.16）进料360的所有补充母羊（90,180 （和360）在将脉搏性和阻力指数归一化为CON时，相对于基线具有负变化（P = 0.02），这分别表明远端组织的血流灌注增加和血管血流阻力降低。此外，对搏动性和阻力指数有二次响应（P分别为0.03和0.01），其中当归一化为CON时，饲喂180只母羊的基线变化最大。结果表明，精氨酸补充剂可增加血清氨基酸浓度并改善外周组织血液灌注。确定180 mg·kg BW ^-1 ·d ^-1 RP-ARG剂量是未怀孕的未产妇Rambouillet母羊的最佳剂量。