Deters Erin L, Niedermayer Emma K, Genther-Schroeder Olivia N, Blank Christopher P, Carmichael Remy N, Hartman Sarah J, Messersmith Elizabeth M, VanValin Katherine R, Branine Mark E, Hansen Stephanie L
Department of Animal Science, Iowa State University, College of Agriculture and Life Sciences, Ames, IA 50011, USA.
Zinpro Corporation, Eden Prairie, MN 55344, USA.
Transl Anim Sci. 2021 May 28;5(2):txab093. doi: 10.1093/tas/txab093. eCollection 2021 Apr.
Angus-crossbred steers ( = 180; 292 ± 18 kg) from a single ranch were used to investigate the effects of a novel rumen-protected folic acid (RPFA) supplement on feedlot performance and carcass characteristics. On d 0, steers were blocked by body weight to pens (5 steers/pen), and pens within a block were randomly assigned to dietary treatments ( = 6 pens/treatment): target intake of 0 (CON), 30 (RPFA-30), 60 (RPFA-60), 90 (RPFA-90), 120 (RPFA-120), or 150 (RPFA-150) mg RPFA·steer·d. Steers were weighed before feeding on d -1, 0, 55, 56, 86, 87, 181, and 182. Pen average daily gain (ADG), dry matter intake (DMI), and gain:feed (G:F) were calculated for growing (d 0 to 56), dietary transition (d 56 to 87), finishing (d 87 to 182), and overall (d 0 to 182). Liver and blood samples were collected from two steers/pen before trial initiation and at the end of growing and finishing. Steers were slaughtered on d 183, and carcass data were collected after a 48-h chill. Data were analyzed as a randomized complete block design using ProcMixed of SAS 9.4 (fixed effects of treatment and block; experimental unit of pen). Liver abscess scores were analyzed using the Genmod Procedure of SAS 9.4. Contrast statements assessed the polynomial effects of RPFA. Supplemental RPFA linearly increased plasma folate at the end of growing and finishing ( < 0.01), and linearly decreased plasma glucose at the end of growing ( = 0.01). There was a cubic effect of RPFA on liver folate at the end of growing ( = 0.01), driven by lesser concentrations for RPFA-30, RPFA-60, and RPFA-150. Growing period ADG and G:F were greatest for CON and RPFA-120 (cubic ≤ 0.03). Transition period DMI was linearly increased due to RPFA ( = 0.05). There was a tendency for a cubic effect of RPFA on the percentage of livers with no abscesses ( = 0.06), driven by a greater percentage of non-abscessed livers in RPFA-30 and RPFA-60. Despite supplementing 1 mg Co/kg DM, and regardless of treatment, plasma vitamin B12 concentrations were low (<200 pg/mL), which may have influenced the response to RPFA as vitamin B12 is essential for recycling of folate.
来自一个牧场的安格斯杂交阉牛（n = 180；体重292±18千克）用于研究一种新型瘤胃保护叶酸（RPFA）添加剂对饲养场性能和胴体特性的影响。在第0天，根据体重将阉牛分栏至围栏（每栏5头阉牛），同一栏内的围栏随机分配至不同日粮处理（每个处理6栏）：RPFA的目标摄入量为0（CON）、30（RPFA - 30）、60（RPFA - 60）、90（RPFA - 90）、120（RPFA - 120）或150（RPFA - 150）毫克/头·天。在第 - 1、0、55、56、86、87、181和182天饲喂前对阉牛进行称重。计算生长阶段（第0至56天）、日粮转换阶段（第56至87天）、育肥阶段（第87至182天）和整个阶段（第0至182天）每栏的平均日增重（ADG）、干物质摄入量（DMI）和增重：饲料比（G:F）。在试验开始前以及生长和育肥结束时，从每栏中选取2头阉牛采集肝脏和血液样本。在第183天对阉牛进行屠宰，并在冷藏48小时后收集胴体数据。使用SAS 9.4的ProcMixed程序将数据作为随机完全区组设计进行分析（处理和区组的固定效应；围栏为实验单位）。使用SAS 9.4的Genmod程序分析肝脏脓肿评分。对比语句评估了RPFA的多项式效应。补充RPFA使生长和育肥结束时血浆叶酸线性增加（P < 0.01），并使生长结束时血浆葡萄糖线性降低（P = 0.01）。生长结束时，RPFA对肝脏叶酸有三次效应（P = 0.01），这是由RPFA - 30、RPFA - 60和RPFA - 150较低的浓度所驱动。CON和RPFA - 120的生长阶段ADG和G:F最高（三次效应P≤0.03）。由于RPFA，转换阶段DMI线性增加（P = 0.05）。RPFA对无脓肿肝脏百分比有三次效应的趋势（P = 0.06），这是由RPFA - 30和RPFA - 60中无脓肿肝脏的百分比更高所驱动。尽管每千克干物质补充了1毫克钴，且无论处理如何，血浆维生素B12浓度都很低（<200皮克/毫升），这可能影响了对RPFA的反应，因为维生素B12对于叶酸的循环利用至关重要。
