High twin lamb mortality in Merino sheep is a major cost for the Australian wool and sheep meat industry. Most lambs die within three days of birth due to low birthweight and/or complications arising during parturition. Maternal arginine supplementation can potentially increase birthweight by improving utero-placental haemodynamics; but availability and cost of rumen-protected arginine are barriers. Therefore, we sought to increase circulating concentrations of arginine, lamb birthweight and survival by supplementing twin-bearing Merino ewes with lysine, methionine and choline from day 80 of gestation (dG 80) to parturition. Each day, ewes were individually fed a supplement (barley, pea, pollard and molasses) with addition of either 14 g lysine, 7 g methionine and 7 g choline (amino acid; AA; n = 48); or no amino acids (control; CTL; n = 48). Supplementation did not alter circulating amino acid profiles in ewes at dG 120. Parturition difficulty of ewes and meconium staining of lambs did not differ between AA and CTL groups. Rectal temperatures during the first 24 h of life and serum IgG concentrations (indicative of colostrum intake) at 24 h after birth were similar in lambs born to AA and CTL ewes. AA supplementation did not alter lamb weights from birth to weaning (~three months of age), or lamb survival to weaning (CTL: 75%; AA: 84.8%, P > 0.05). The lack of response to maternal supplementation with this combination of rumen-protected lysine, methionine and choline suggests that alternate strategies are needed to increase maternal arginine abundance and twin lamb survival.

美利奴羊的高双生羔死亡率是澳大利亚羊毛和羊肉产业的主要成本。由于低出生体重和/或分娩过程中出现的并发症，大多数羔羊在出生后三天内死亡。母亲补充精氨酸可能通过改善子宫胎盘血流动力学增加出生体重；但瘤胃保护精氨酸的可用性和成本是障碍。因此，我们试图通过从妊娠 80 天 (dG 80) 到分娩向双胎美利奴母羊补充赖氨酸、蛋氨酸和胆碱来提高精氨酸的循环浓度、羔羊出生体重和存活率。每天，给母羊单独喂食补充剂（大麦、豌豆、花粉和糖蜜），其中添加了 14 g 赖氨酸、7 g 蛋氨酸和 7 g 胆碱（氨基酸；AA；n = 48); 或没有氨基酸（对照；CTL；n  = 48）。在 dG 120 时补充并没有改变母羊的循环氨基酸谱。母羊的分娩困难和羔羊的胎粪染色在 AA 和 CTL 组之间没有差异。出生后最初 24 小时的直肠温度和出生后 24 小时的血清 IgG 浓度（指示初乳摄入量）在 AA 和 CTL 母羊出生的羔羊中相似。AA 补充剂不会改变从出生到断奶（~三个月大）的羔羊体重，或从断奶到断奶的羔羊存活率（CTL：75%；AA：84.8%，P> 0.05）。对母体补充这种瘤胃保护赖氨酸、蛋氨酸和胆碱的组合缺乏反应表明需要替代策略来增加母体精氨酸丰度和双胞胎存活率。