Department of Animal Sciences, Purdue University, West Lafayette, IN 47907.
Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907.
J Dairy Sci. 2022 Sep;105(9):7738-7749. doi: 10.3168/jds.2021-21567. Epub 2022 Aug 6.
It is necessary for the dairy industry to reduce calf morbidity and mortality, and the reliance on antibiotics to treat sick calves, to address the growing concern regarding antibiotic resistant bacteria. The primary objective of this study was to evaluate the effect that feeding dairy calves medium-chain fatty acids (MCFA) has on growth performance and health, and the secondary objective was to evaluate the effect of MCFA on energy status around weaning and the adaptive immune response following a vaccine challenge. Thirty-three Holstein bull calves (5 ± 1.6 d of age) were randomly assigned to 1 of 2 treatments. Control (CON) calves were fed milk replacer with no C8:0 or C10:0 oil added and MCFA calves were fed milk replacer with 0.5% of a combination of C8:0 or C10:0 oil added. Body weight and average daily gain were measured weekly. Feed efficiency (gain/feed) and the change in body condition score, hip width, hip height, heart girth, and paunch girth were calculated for the duration of the study. Fecal scores were recorded daily and all medical treatments were documented for the duration of the trial. On d 42, 49, and 56 of the study, a serum sample was collected from each calf and used to measure nonesterified fatty acids, β-hydroxybutyric acid, insulin, and glucose concentrations to evaluate energy status around weaning. A subset of 11 calves per treatment were enrolled in a vaccine challenge. At 21 ± 1.9 d of age (mean ± standard deviation) calves were vaccinated intramuscularly with 1 mL of endotoxin-free ovalbumin (OVA) mixed with aluminum hydroxide adjuvant. At 42 d of age (±1.9 d), blood samples were collected and used to analyze OVA-specific IgG and IgG, and calves were vaccinated a second time. At 56 d of age (±1.9 d), blood samples were collected to analyze IgG and IgG as well as IFN-γ and IL-4 secreted from peripheral blood mononuclear cells (PBMC) treated with OVA or phytohemagglutinin. Data were analyzed as a completely randomized design with repeated measures when applicable. A tendency for greater daily fecal score was observed for MCFA calves compared with CON. At d 42 of the study, nonesterified fatty acid concentrations were greater in CON calves compared with MCFA. At 42 and 56 d of age, anti-OVA IgG concentrations for CON and MCFA calves were greater than prevaccination samples. This study suggests that feeding MCFA to calves affects the energy status of calves around weaning and vaccinating dairy calves with ovalbumin combined with an aluminum hydroxide adjuvant is an effective way to evaluate the adaptive immune responses.
为了应对人们对耐药菌日益增长的担忧，乳制品行业有必要降低犊牛的发病率和死亡率，并减少对抗生素的依赖来治疗患病犊牛。本研究的主要目的是评估给奶牛犊牛饲喂中链脂肪酸（MCFA）对其生长性能和健康的影响，次要目的是评估 MCFA 对断奶前后能量状态和疫苗接种后适应性免疫反应的影响。33 头荷斯坦公牛犊（5±1.6 日龄）被随机分配到 2 种处理中的 1 种。对照（CON）犊牛饲喂不含 C8:0 或 C10:0 油的代乳料，MCFA 犊牛饲喂含有 0.5% C8:0 或 C10:0 油组合的代乳料。每周测量体重和平均日增重。在研究期间计算饲料效率（增重/饲料）和体况评分、髋宽、髋高、胸围和腹围的变化。每天记录粪便评分，并记录整个试验期间的所有医疗处理情况。在研究的第 42、49 和 56 天，从每头犊牛采集血清样本，用于测量非酯化脂肪酸、β-羟丁酸、胰岛素和葡萄糖浓度，以评估断奶前后的能量状态。每个处理组中有 11 头犊牛被纳入疫苗接种挑战。犊牛在 21±1.9 日龄（平均值±标准差）时肌肉内注射 1mL 无内毒素卵清蛋白（OVA）与氢氧化铝佐剂混合。在 42 日龄（±1.9 天）时，采集血液样本并分析 OVA 特异性 IgG 和 IgG，然后再次给犊牛接种疫苗。在 56 日龄（±1.9 天）时，采集血液样本以分析 IgG 和 IgG 以及外周血单个核细胞（PBMC）经 OVA 或植物血凝素处理后分泌的 IFN-γ和 IL-4。数据采用完全随机设计分析，当适用时采用重复测量。与 CON 组相比，MCFA 组犊牛的每日粪便评分有升高的趋势。在研究的第 42 天，CON 组犊牛的非酯化脂肪酸浓度高于 MCFA 组。在 42 和 56 日龄时，CON 和 MCFA 组犊牛的抗 OVA IgG 浓度高于疫苗接种前的样本。本研究表明，给犊牛饲喂 MCFA 会影响其断奶前后的能量状态，用卵清蛋白和氢氧化铝佐剂给奶牛犊牛接种疫苗是评估适应性免疫反应的有效方法。
