Department of Animal Science, Iowa State University, Ames 50011.
Universidad Autónoma Chapingo, General Villegas, Chapingo, México.
J Dairy Sci. 2020 Aug;103(8):7451-7461. doi: 10.3168/jds.2020-18151. Epub 2020 May 21.
Objectives were to evaluate the effects of rumen-protected glucose (RPG) supplementation on milk production, post-absorptive metabolism, and inflammatory biomarkers in transition dairy cows. Fifty-two multiparous cows were blocked by previous 305-d mature-equivalent milk (305ME) yield and randomly assigned to 1 of 2 iso-energetic and iso-nitrogenous treatments: (1) control diet (CON; n = 26) or (2) a diet containing RPG (pre-fresh 5.3% of dry matter and 6.0% of dry matter postpartum; n = 26). Cows received their respective dietary treatments from d -21 to 28 relative to calving, and dry matter intake was calculated daily during the same period. Weekly body weight, milk composition, and fecal pH were recorded until 28 d in milk (DIM), and milk yield was recorded through 105 DIM. Blood samples were collected on d -7, 3, 7, 14, and 28 relative to calving. Data were analyzed using repeated measures in the MIXED procedure (SAS Institute Inc., Cary, NC) with previous 305ME as a covariate. Fecal pH was similar between treatments and decreased (0.6 units) postpartum. Dry matter intake pre- and postpartum were unaffected by treatment, as was milk yield during the first 28 or 105 DIM. Milk fat, protein, and lactose concentration were similar for both treatments. Blood urea nitrogen and plasma glucose concentrations were unaffected by treatment; however, results showed increased concentration of circulating insulin (27%), lower nonesterified fatty acids (28%), and lower postpartum β-hydroxybutyrate (24%) in RPG-fed cows. Overall, circulating lipopolysaccharide-binding protein and haptoglobin did not differ by treatment, but at 7 DIM, RPG-fed cows had decreased lipopolysaccharide-binding protein and haptoglobin concentrations (31 and 27%, respectively) compared with controls. Supplemental RPG improved some biomarkers of post-absorptive energetics and inflammation during the periparturient period, changes primarily characterized by increased insulin and decreased nonesterified fatty acids concentrations, with a concomitant reduction in acute phase proteins without changing milk production and composition.
目的在于评估瘤胃保护葡萄糖（RPG）补充对产奶量、吸收后代谢和过渡奶牛炎症生物标志物的影响。52 头经产奶牛根据前 305 天成熟当量奶（305ME）产量进行分组，然后随机分为 2 种等能量和等氮处理之一：（1）对照日粮（CON；n = 26）或（2）含 RPG 日粮（产前干物质的 5.3%和产后干物质的 6.0%；n = 26）。奶牛从产犊前 21 天到 28 天接受各自的日粮处理，同时在同一时期每天计算干物质摄入量。每周记录体重、牛奶成分和粪便 pH，直至产犊后 28 天（DIM），并通过 105 DIM 记录牛奶产量。在产犊前 7、3、7、14 和 28 天采集血液样本。使用混合模型（MIXED）程序（SAS Institute Inc.，Cary，NC）进行重复测量分析，将前 305ME 作为协变量。粪便 pH 在处理之间相似，产后降低（0.6 个单位）。处理对干物质摄入量产前后均无影响，前 28 天或 105 DIM 的牛奶产量也不受影响。两种处理的牛奶脂肪、蛋白质和乳糖浓度相似。处理对血液尿素氮和血浆葡萄糖浓度无影响；然而，结果表明，在 RPG 喂养的奶牛中，循环胰岛素浓度增加（27%）、非酯化脂肪酸降低（28%）和产后 β-羟丁酸降低（24%）。总体而言，循环脂多糖结合蛋白和触珠蛋白的处理间没有差异，但在 7 DIM，与对照组相比，RPG 喂养的奶牛脂多糖结合蛋白和触珠蛋白浓度降低（分别为 31%和 27%）。补充 RPG 改善了围产期吸收后能量和炎症的一些生物标志物，这些变化主要表现为胰岛素增加和非酯化脂肪酸浓度降低，同时急性相蛋白减少而不改变产奶量和组成。
