Department of Animal Science and Interdepartmental Nutrition Program, North Carolina State University, Raleigh 27695-7621, USA.
J Anim Sci. 2011 Aug;89(8):2502-9. doi: 10.2527/jas.2010-3265. Epub 2011 Mar 7.
The objective of this study was to determine if dietary cation-anion balance (DCAB) affects the concentration of S that can be tolerated by growing and finishing cattle without adversely affecting performance. Angus cross and Bradford steers (n=114; average initial BW=252.8 kg) were blocked by BW and breed, and randomly assigned within a block to treatment. The design was a 3 × 2 factorial arrangement of treatments with S (from NH(4)SO(4)) supplemented at 0, 0.15, or 0.30% of DM, and NaHCO(3) added at 0 or 1.0% of DM. Each treatment consisted of 3 pens containing 5 steers and 1 pen containing 4 steers. Steers were used in an 84-d growing study followed by a finishing study. A corn silage-based diet was fed during the growing study and a corn-based diet was fed during the finishing study. Steers were not randomized between experiments. The analyzed concentrations of S in the growing diets were 0.12, 0.30, and 0.46%, whereas the analyzed concentrations of S in the finishing diets were 0.13, 0.31, and 0.46% for treatments supplemented with 0, 0.15, and 0.30% S, respectively. Increasing DCAB by approximately 15 mEq/100 g of DM, by the addition of NaHCO(3,) did not affect (P > 0.36) performance during the growing or finishing studies. During the growing study DMI was not affected (P=0.29) by dietary S. Steers fed diets containing 0.30% S had greater ADG (P=0.02) and G:F (P=0.01) than those receiving 0.46% S, but similar (P > 0.36) performance to steers fed 0.12% S. During the finishing study, steers fed diets containing 0.46% S had less ADG than steers fed 0.13 (P=0.004) or 0.31% S (P=0.07), whereas ADG did not differ (P=0.18) among steers fed 0.13 and 0.31% S. Steers fed diets containing 0.31 (P=0.01) or 0.46% S (P=0.001) had less DMI than controls, but G:F was not affected (P=0.52) by S during the finishing study. Carcass characteristics did not differ (P > 0.18) among steers fed diets containing 0.13 and 0.31% S. Steers receiving diets containing 0.46% S had decreased HCW (P=0.001), quality (P=0.02), and yield grades (P=0.04) than steers receiving 0.13% S. Plasma Cu concentrations on d 101 of the finishing phase and liver Cu concentrations at slaughter were greater (P ≤ 0.05) in control steers compared with those fed diets containing 0.31 or 0.46% S. This study indicates that steers fed growing diets can tolerate up to 0.46% S with minimum effects on performance. Finishing steers tolerated diets containing 0.31% S without adverse affects on ADG or G:F. However, 0.46% S greatly decreased ADG and DMI, and increasing DCAB did not prevent these depressions.
本研究旨在确定日粮阴阳离子平衡（DCAB）是否会影响生长育肥牛对 S 的耐受浓度，而不会对其生产性能产生不利影响。 Angus 杂交牛和 Bradford 阉牛（n=114；平均初始 BW=252.8kg）按 BW 和品种分组，在每个组内随机分配到处理组中。试验采用 3×2 因子设计，其中 S（来自 NH4SO4）以 0、0.15 或 0.30%的 DM 补充，NaHCO3 以 0 或 1.0%的 DM 添加。每个处理组包含 3 个栏，每个栏包含 5 头阉牛，1 个栏包含 4 头阉牛。阉牛在为期 84d 的生长试验后进行育肥试验。在生长试验中，使用以玉米青贮为基础的日粮，在育肥试验中，使用以玉米为基础的日粮。阉牛在两个试验之间不随机分组。生长试验中，分析的 S 浓度分别为 0.12%、0.30%和 0.46%，而育肥试验中，补充 0、0.15 和 0.30%S 的处理的分析 S 浓度分别为 0.13%、0.31%和 0.46%。通过添加 NaHCO3，使 DCAB 增加约 15 mEq/100g DM 不会（P＞0.36）影响生长或育肥试验期间的生产性能。在生长试验中，日粮 S 不影响（P=0.29）DMI。与接受 0.46% S 的阉牛相比，饲喂 0.30% S 的日粮的阉牛具有更高的 ADG（P=0.02）和 G:F（P=0.01），但与饲喂 0.12% S 的阉牛的生产性能相似（P＞0.36）。在育肥试验中，与饲喂 0.13%或 0.31% S 的阉牛相比，饲喂 0.46% S 的阉牛的 ADG 更低（P=0.004），而饲喂 0.13%和 0.31% S 的阉牛之间 ADG 没有差异（P=0.18）。饲喂含有 0.31%（P=0.01）或 0.46% S（P=0.001）的日粮的阉牛比对照组的 DMI 更少，但 S 对育肥试验期间的 G:F 没有影响（P=0.52）。饲喂 0.13%和 0.31% S 的日粮的阉牛的胴体特性没有差异（P＞0.18）。与饲喂 0.13% S 的阉牛相比，饲喂 0.46% S 的阉牛的 HCW（P=0.001）、肉质（P=0.02）和产肉等级（P=0.04）降低。与饲喂含有 0.31%或 0.46% S 的日粮的阉牛相比，宰前育肥阶段第 101d 的血浆 Cu 浓度和肝脏 Cu 浓度更高（P≤0.05）。本研究表明，生长育肥阉牛可耐受高达 0.46%的 S，对生产性能的影响最小。育肥阉牛可耐受含有 0.31% S 的日粮，而对 ADG 或 G:F 没有不利影响。然而，0.46% S 大大降低了 ADG 和 DMI，而增加 DCAB 并不能防止这些下降。
