Department of Animal Science and Interdepartmental Graduate Program in Nutritional Sciences, Iowa State University, Ames, Iowa 50011, USA.
J Anim Sci. 2013 Sep;91(9):4303-14. doi: 10.2527/jas.2012-5638. Epub 2013 Jul 12.
The objective of this study was to examine the effects of supplemental rumen-protected vitamin C (VC) on live and carcass-based performance, and antioxidant capacity of cattle consuming varying concentrations of dietary S. Angus-cross steers (n = 120) were blocked by initial BW (341 ± 11 kg) and assigned equally to 1 of 6 treatments, evaluating 3 concentrations of dietary S [0.22%, 0.34%, and 0.55%, for low S (LS), medium S (MS), and high S (HS), respectively] and 2 concentrations of supplemental VC (0 or 10 g • steer(-1) • d(-1)). Steers receiving VC-supplemented diets consumed an average of 10.3 g of supplemental VC • steer(-1) • d(-1) and increasing dietary S linearly increased (P < 0.01) grams of S consumed. Increasing dietary S decreased (P < 0.01) DMI, final BW, and ADG, and linearly increased (P < 0.05) rumen hydrogen sulfide and blood sulfhemoglobin concentrations. The inclusion of VC, regardless of S treatment, tended to increase (P = 0.08) plasma VC concentrations, specifically within the medium and high S diets (P = 0.04). Plasma total antioxidant capacity (d 90) linearly decreased (P = 0.003) and total liver glutathione (GSH; d 143) tended to decrease (P = 0.08) due to increased S intake. Within the high S treatment, addition of VC decreased (P = 0.04) the ratio of oxidized-to-reduced GSH compared with HS alone. Increased dietary S and VC decreased (P < 0.05) plasma Cu concentrations, whereas VC increased (P = 0.01) plasma Fe concentrations. Linear decreases (P < 0.02) in marbling score, backfat thickness (BF), yield grade, and HCW were observed as dietary S increased; however, the addition of VC to the HS diet increased (P < 0.01) BF, marbling scores, and percentage of cattle grading Choice compared with HS without VC. In conclusion, supplementation of VC to cattle receiving the high S diet improved marbling scores; although the exact mechanism for this improvement is unknown, it may be related to greater circulating VC available for lipid metabolism in these cattle.
本研究旨在探讨日粮中添加保护性维生素 C（VC）对牛活重和胴体性能以及抗氧化能力的影响。选择初始体重（341±11kg）相近的 Angus 杂交公牛（n=120），按初始体重分为 6 组，每组 20 头，分别饲喂含不同水平硫（0.22%、0.34%和 0.55%，分别对应低硫 LS、中硫 MS 和高硫 HS）的日粮和添加或不添加 VC（0 或 10g·头-1·d-1）的日粮。结果表明：添加 VC 组牛的 VC 摄入量平均为 10.3g·头-1·d-1，且随着日粮硫水平的增加，硫的摄入量呈线性增加（P<0.01）。增加日粮硫降低了（P<0.01）干物质采食量、终重和平均日增重，且线性增加了（P<0.05）瘤胃中硫化氢和血液高铁血红蛋白的浓度。无论硫处理如何，添加 VC 都会增加（P=0.08）血浆 VC 浓度，特别是在中、高硫日粮中（P=0.04）。血浆总抗氧化能力（d90）呈线性下降（P=0.003），总肝谷胱甘肽（GSH；d143）呈下降趋势（P=0.08），这是由于硫摄入量的增加。在高硫处理中，与单独高硫处理相比，添加 VC 降低了（P=0.04）氧化型与还原型 GSH 的比值。增加日粮硫和 VC 降低了（P<0.05）血浆铜浓度，而 VC 增加了（P=0.01）血浆铁浓度。随着日粮硫水平的增加，大理石花纹评分、背膘厚（BF）、产肉率和宰前活重呈线性下降（P<0.02）；然而，与高硫日粮相比，高硫日粮中添加 VC 增加了（P<0.01）BF、大理石花纹评分和牛肉达到 Choice 级别的比例。总之，给高硫日粮组牛补充 VC 提高了大理石花纹评分；尽管确切的改善机制尚不清楚，但这可能与这些牛体内更多可用于脂质代谢的循环 VC 有关。
