We have previously reported that supplementation with Saccharomyces cerevisiae fermentation products (SCFP) ameliorates clinical signs and lung pathology following experimental bovine respiratory syncytial virus (BRSV) infection in preweaned dairy calves. The objectives of this study were to determine the effect of SCFP supplementation on the metabolic and endocrine responses, and disease outcome of a viral–bacterial coinfection in preweaned calves. Twenty-seven, 1- to 2-d-old Holstein-Angus cross calves were enrolled in the study; one SCFP calf was removed from the trial during the pre-challenge phase due to complications from nephritis. Calves were assigned to two treatment groups: control or SCFP-treated, base milk replacer with 1 g/d SCFP (Smartcare, soluble formula) and calf starter top dressed with 5 g/d SCFP (NutriTek, insoluble formula). Calves were infected with BRSV on day 21, followed 6 d later by intratracheal inoculation with Pasteurella multocida (PM). Calves were euthanized on day 10 post-viral infection. Calves receiving SCFP had reduced thoracic ultrasonography scores on day 7 post-viral infection (P = 0.03) and a tendency toward reduced scores on day 10 post-viral infection (P = 0.09). Calves receiving SCFP also had less severe lung pathology scores at necropsy (P = 0.06). No differences between treatments were observed in lung viral loads (P = 0.48) or bacterial lung recovery (P = 0.34); however, there was a distinction in the lung location for PM recovery, with PM isolated more frequently from the cranial lobes in SCFP-treated calves, but more frequently from the caudal lobes of control calves. Calves treated with SCFP tended (P = 0.07) to have higher serum IL-6 concentrations following the coinfection. Calves treated with SCFP had lower concentrations of serum nonesterified fatty acids and beta-hydroxybutyric acid compared with controls following experimental challenge (P = 0.03 and P = 0.08, respectively), suggesting metabolic changes favoring growth and development. There were no differences between groups in gene expression of insulin receptor, insulin-like growth factor 1 (IGF-1), IGF-1 receptor (IGF-1R), growth hormone receptor, or haptoglobin in the liver. Results from this study suggest that supplementing with SCFP may moderate the impact of a respiratory viral–bacterial coinfection on preweaned calves through metabolic and immune modifications.

中文翻译：

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饲喂酿酒酵母发酵产品可减轻断奶前犊牛病毒-细菌双重感染的严重程度


我们之前曾报道，补充酿酒酵母发酵产品 (SCFP) 可改善断奶前奶牛实验性牛呼吸道合胞病毒 (BRSV) 感染后的临床症状和肺部病理学。本研究的目的是确定补充 SCFP 对断奶前犊牛代谢和内分泌反应以及病毒-细菌双重感染疾病结果的影响。 27 头 1 至 2 日龄的荷斯坦-安格斯杂交小牛参与了这项研究；由于肾炎并发症，一头 SCFP 小牛在攻击前阶段被从试验中移除。犊牛被分配到两个处理组：对照组或 SCFP 处理组，基础代乳品添加 1 g/d SCFP（Smartcare，可溶性配方奶粉），犊牛开食料添加 5 g/d SCFP（NutriTek，不溶性配方奶粉）。小牛在第 21 天感染 BRSV，6 天后气管内接种多杀性巴氏杆菌 (PM)。小牛在病毒感染后第10天被安乐死。接受 SCFP 的犊牛在病毒感染后第 7 天胸部超声检查评分降低（P = 0.03），并且在病毒感染后第 10 天评分有降低的趋势（P = 0.09）。接受 SCFP 的小牛在尸检时的肺部病理评分也较轻 (P = 0.06)。在肺病毒载量（P = 0.48）或细菌肺恢复（P = 0.34）方面没有观察到治疗之间的差异；然而，PM 恢复的肺部位置存在差异，在 SCFP 处理的犊牛中，PM 更频繁地从颅叶中分离出来，但更频繁地从对照犊牛的尾叶中分离出来。使用 SCFP 治疗的犊牛在共感染后往往具有较高的血清 IL-6 浓度 (P = 0.07)。 与实验挑战后的对照相比，用 SCFP 治疗的小牛血清非酯化脂肪酸和 β-羟基丁酸浓度较低（分别为 P = 0.03 和 P = 0.08），表明代谢变化有利于生长和发育。肝脏中胰岛素受体、胰岛素样生长因子 1 (IGF-1)、IGF-1 受体 (IGF-1R)、生长激素受体或触珠蛋白的基因表达在各组之间没有差异。这项研究的结果表明，补充 SCFP 可能会通过代谢和免疫调节来减轻呼吸道病毒-细菌双重感染对断奶前犊牛的影响。