Endometrial-derived uterine histotroph is a critical component of nutrient supply to a growing conceptus throughout gestation; however, the effect of nutritional plane on histotroph nutrient composition remains unknown in multiparous cows. We hypothesized that differing planes of nutrition would alter histotroph and serum nutrient composition in beef cattle. Thus, we evaluated serum and histotroph amino acid and glucose composition, and serum non-esterified fatty acids (NEFA) and blood urea nitrogen (BUN) in cows individually fed to maintain body weight (0 kd/d, n = 9; CON) compared with those losing moderate body weight (-0.7 kg/d, n = 9; NEG). After 49 d of differing nutritional planes, cows were subjected to the 7-d CoSynch + CIDR estrus synchronization protocol and then slaughtered on d 62. Blood serum (d 0 and 62) and uterine histotroph [d 62; from uterine horns ipsilateral and contralateral to the corpus luteum (CL)] were collected and analyzed for concentrations of amino acids, glucose, and NEFA. Performance characteristics, body composition via ultrasound (d 0 and 62), and carcass characteristics were collected. Body condition score, change in body weight, average daily gain (ADG), dry matter intake (DMI), and gain:feed (G:F) were decreased (P ≤ 0.05) in NEG vs. CON cows. There were no differences in body composition or carcass characteristics, except an increase (P ≤ 0.05) in dressing percentage in NEG cows due to differences in gut fill, consistent with study design. Serum NEFA increased (P ≤ 0.05) in the NEG group, but there were no differences between NEG vs. CON in glucose or BUN. Serum histidine increased (P ≤ 0.05) and alanine, isoleucine and tryptophan decreased (P ≤ 0.05) in NEG vs. CON cows. Compared with that of the uterine horn ipsilateral to the CL, histotroph from the uterine horn contralateral to the CL had increased (P ≤ 0.05) isoleucine, asparagine, and proline concentrations in NEG cows, and decreased (P ≤ 0.05) tryptophan as a proportion of essential and total amino acids. There were no differences in glucose concentrations of histotroph contralateral or ipsilateral to the CL. Cow nutritional plane does alter serum and histotroph amino acid composition, although the presence of an embryo may be necessary to fully elucidate these changes. Differences in serum and histotroph tryptophan should be given consideration in future studies due to its importance as an essential amino acid in protein synthesis and bioactive affects.

中文翻译：

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不同的营养水平改变非妊娠多产肉牛在发情周期第三天的血清和组织营养氨基酸组成


子宫内膜来源的子宫组织营养物质是整个妊娠过程中孕体生长的营养供应的关键组成部分；然而，营养平面对经产奶牛组织营养成分的影响仍然未知。我们假设不同的营养平面会改变肉牛的组织营养物质和血清营养成分。因此，我们评估了单独饲喂以维持体重的奶牛的血清和组织营养氨基酸和葡萄糖组成，以及血清非酯化脂肪酸 (NEFA) 和血尿素氮 (BUN)（0 kd/d，n = 9；CON）与中等体重减轻的人相比（-0.7 kg/d，n = 9；NEG）。经过 49 天的不同营养平面后，对奶牛进行 7 天 CoSynch + CIDR 发情同步方案，然后在第 62 天屠宰。血清（第 0 天和第 62 天）和子宫组织营养细胞 [第 62 天；第 62 天；第 62 天]。收集并分析氨基酸、葡萄糖和 NEFA 的浓度。收集性能特征、通过超声检测的身体成分（第 0 天和第 62 天）以及屠体特征。与 CON 奶牛相比，NEG 奶牛的身体状况评分、体重变化、平均日增重 (ADG)、干物质摄入量 (DMI) 和增重：饲料 (G:F) 均降低 (P ≤ 0.05)。除了由于肠道填充差异导致 NEG 奶牛的屠宰百分比增加 (P ≤ 0.05) 外，身体成分或胴体特征没有差异，这与研究设计一致。 NEG 组的血清 NEFA 增加（P ≤ 0.05），但 NEG 与 CON 之间的葡萄糖或 BUN 没有差异。与 CON 奶牛相比，NEG 奶牛的血清组氨酸升高（P ≤ 0.05），丙氨酸、异亮氨酸和色氨酸降低（P ≤ 0.05）。 与 CL 同侧子宫角相比，NEG 奶牛 CL 对侧子宫角的组织营养细胞异亮氨酸、天冬酰胺和脯氨酸浓度增加（P ≤ 0.05），色氨酸比例降低（P ≤ 0.05）必需氨基酸和总氨基酸。 CL 的组织营养细胞对侧或同侧的葡萄糖浓度没有差异。奶牛营养平面确实改变了血清和组织营养氨基酸组成，尽管胚胎的存在可能是充分阐明这些变化所必需的。由于色氨酸作为蛋白质合成和生物活性影响中必需氨基酸的重要性，因此在未来的研究中应考虑血清和组织营养色氨酸的差异。