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首页> 美国卫生研究院文献>Journal of Animal Science >Evaluation of the dietary vitamin A requirement of finishing steers via systematic depletion and repletion and its effects on performance and carcass characteristics
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Evaluation of the dietary vitamin A requirement of finishing steers via systematic depletion and repletion and its effects on performance and carcass characteristics

机译：评价膳食维生素通过系统耗尽和灌注的要求及其对性能和胴体特性的影响

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A randomized complete block design experiment with 30 yearling crossbred steers (initial average body weight [BW] = 297.6 ± 32.8 kg) fed a steam-flaked corn-based diet was used to evaluate finishing performance and carcass characteristics when provided with different concentrations of vitamin A (Rovimix A 1000; DSM Nutritional Products Ltd., Sisseln, Switzerland) subsequent to a depletion phase. Steers were blocked by BW (n = 5 blocks; 6 steers per block), assigned to pens (n = 2 steers per pen), and randomly assigned to one of the following dietary treatments: no added vitamin A (0IU; 0.0 IU/kg dry matter [DM] basis of additional vitamin A), vitamin A supplemented at the estimated National Academies of Sciences, Engineering, and Medicine (NASEM) requirement (2,200IU; 2,200 IU/kg of dietary DM of additional vitamin A), and vitamin A supplemented at 5× the estimated requirement (11,000IU; 11,000 IU/kg of dietary DM of additional vitamin A). The basal diet included minimal vitamin A activity (<200 IU of vitamin A activity/kg of dietary DM) via the provitamin A, beta-carotene. After all animals underwent a 91-d vitamin A depletion period, additional vitamin A was top-dressed at feeding via a ground corn carrier. Liver biopsy samples, BW, and blood were obtained on days −91, −35, 0, 28, 56, 84, and 112. Final BW was collected prior to shipping on day 112. Carcass data were collected by trained personnel upon harvest. Sera and liver samples were used to monitor circulating vitamin A and evaluate true vitamin A status of the cattle. Vitamin A status did not affect interim average daily gain or feed efficiency (G:F; P > 0.05). Throughout the duration of the study, dry matter intake for the 0IU cattle was depressed (P = 0.01). Differences were not observed across treatments for hot carcass weight, rib eye area, back fat thickness, kidney–pelvic–heart fat %, marbling score, or dressing percent (P ≥ 0.10). A treatment × day interaction occurred for both (P < 0.01) sera retinol and liver retinol during phase 2 of the trial. The treatments and sera retinol concentrations were incorporated into a repletion model, resulting in an estimation of liver retinol changes (P < 0.01; R2 = 0.682). However, models used to evaluate depleted animals were less effective. The current NASEM recommended that vitamin A requirement of 2,200 IU/kg is adequate for repletion of vitamin A status of feedlot steers.
机译：随机完整块设计实验，具有30岁七分杂交配角（初始平均体重[BW] = 297.6±32.8千克），用于评估当提供不同浓度的维生素时进行精加工性能和胴体特性。 A（Rovimix A 1000; DSM营养产品有限公司，SISSELN，瑞士）随后耗尽阶段。用BW（n = 5块;每块6个座位）阻塞，分配给钢笔（每支笔= 2个磁带），随机分配给以下膳食处理之一：没有添加维生素A（0iu; 0.0 IU / kg干物质[dm]的额外维生素a），维生素A补充在估计的国家科学院，工程和医学（NASEM）要求（2,200U; 2,200 IU / Kg膳食DM的额外维生素A），和维生素A补充了5倍的估计要求（11,000iu; 11,000 Iu / kg膳食DM的额外维生素A）。基础饮食包括最小的维生素A活动（通过Provitamin A，β-胡萝卜素A，β-胡萝卜素<200UU的维生素A活性/ kg饮食DM）。在所有动物都经历了91-D维生素的耗尽期后，额外的维生素A通过地下玉米载体喂食。肝活检样品，BW和血液是在第91天，-35,0,28,56,84和112时获得的。在第112天之前收集最终BW。通过收获的培训人员收集胴体数据。血清和肝脏样品用于监测循环维生素A并评估真正的维生素A牛的状态。维生素A状态不会影响临时平均每日增益或饲料效率（G：F; P> 0.05）。在整个研究期间，抑制0IU牛的干物质摄入量（P = 0.01）。在热胴体重量，肋眼面积，背部脂肪厚度，肾盂 - 心脏脂肪％，大理石植物评分或敷料百分比（p≥0.10），未观察到差异。在试验第2期期间（P <0.01）血清视黄醇和肝脏视黄醇发生治疗×白天相互作用。将处理和血清视黄醇浓度掺入完型中，导致肝脏视黄醇的估计变化（P <0.01; R2 = 0.682）。然而，用于评估耗尽的动物的模型效果较小。目前的NASEM建议维生素的要求2,200 IU / kg是足以补充维生素的饲养带状炉的状态。

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