Department of Animal Sciences, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster 44691.
Department of Animal Sciences, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster 44691.
J Dairy Sci. 2017 Jul;100(7):5358-5367. doi: 10.3168/jds.2016-12095. Epub 2017 Apr 27.
Excess rumen-soluble Cu and Zn can alter rumen microbial populations and reduce fiber digestibility. Because of differences in particle size and chemical composition, ruminal and total-tract digestibility of fiber from forage- and by-product-based diets can differ. We hypothesized that, because of differences in mineral solubility, diets with hydroxy rather than sulfate trace minerals would have greater fiber digestibility, but the effect may depend on source of fiber. Eighteen multiparous cows were used in a split-plot replicated Latin square with two 28-d periods to evaluate the effects of Cu, Zn, and Mn source (sulfates or hydroxy; Micronutrients USA LLC, Indianapolis, IN) and neutral detergent fiber (NDF) source (forage diet = 26% NDF vs. by-product = 36%) on total-tract nutrient digestibility. During the entire experiment (56 d) cows remained on the same fiber treatment, but source of supplemental trace mineral was different for each 28-d period so that all cows were exposed to both mineral treatments. During each of the two 28-d periods, cows were fed no supplemental Cu, Zn, or Mn for 16 d followed by 12 d of feeding supplemental Cu, Zn, and Mn from either sulfates or hydroxy sources. Supplemental minerals for each of the mineral sources fed provided approximately 10, 35, and 32 mg/kg of supplemental Cu, Zn, and Mn, respectively, for both fiber treatments. Total dietary concentrations of Cu, Zn, and Mn were approximately 19, 65, and 70 mg/kg for the forage diets and 21, 85, and 79 mg/kg for the by-product diets, respectively. Treatment had no effect on dry matter intake (24.2 kg/d) or milk production (34.9 kg/d). Milk fatty acid profiles were altered by fiber source, mineral source, and their interaction. Cows fed the by-product diets had lower dry matter (65.9 vs. 70.2%), organic matter (67.4 vs. 71.7%), and crude protein digestibility (58.8 vs. 62.1%) but greater starch (97.5 vs. 96.3%) and NDF digestibility (50.5 vs. 44.4%) compared with cows fed the forage treatment. Feeding increased concentrations of by-products decreased total digestible nutrients regardless of mineral source. Feeding hydroxy Cu, Zn, and Mn increased NDF digestibility (48.5 vs. 46.4%) but had no effect on total digestible nutrients.
过量的瘤胃可溶性铜和锌会改变瘤胃微生物种群，降低纤维消化率。由于颗粒大小和化学成分的不同，基于饲料和副产品的日粮的纤维在瘤胃和全肠道的消化率可能不同。我们假设，由于矿物质溶解度的差异，含有羟基而不是硫酸盐的痕量矿物质的日粮的纤维消化率会更高，但这种效果可能取决于纤维的来源。18 头经产奶牛采用两期 28 天重复拉丁方设计，评估铜、锌和锰的来源（硫酸盐或羟基；印第安纳波利斯的 Micronutrients USA LLC）和中性洗涤纤维（NDF）的来源（饲料日粮 = 26% NDF 与副产品 = 36%）对全肠道养分消化率的影响。在整个试验（56 天）期间，奶牛一直处于相同的纤维处理，但补充痕量矿物质的来源在每个 28 天周期中都不同，因此所有奶牛都接触到两种矿物质处理。在两个 28 天周期中的每一个周期中，奶牛在 16 天内不补充铜、锌或锰，然后在 12 天内补充来自硫酸盐或羟基来源的铜、锌和锰。对于两种纤维处理，每种矿物质来源提供的补充矿物质分别约为 10、35 和 32mg/kg 的补充铜、锌和锰。对于饲料日粮，总日粮铜、锌和锰的浓度分别约为 19、65 和 70mg/kg，对于副产品日粮，总日粮铜、锌和锰的浓度分别约为 21、85 和 79mg/kg。处理对干物质采食量（24.2kg/d）或产奶量（34.9kg/d）没有影响。脂肪酸组成受纤维来源、矿物质来源及其相互作用的影响。饲喂副产品日粮的奶牛干物质（65.9%比 70.2%）、有机物（67.4%比 71.7%）和粗蛋白消化率（58.8%比 62.1%）较低，但淀粉（97.5%比 96.3%）和 NDF 消化率（50.5%比 44.4%）较高与饲喂饲料处理的奶牛相比。增加副产品的浓度会降低无论矿物质来源如何的总可消化养分。饲喂羟基铜、锌和锰提高了 NDF 消化率（48.5%比 46.4%），但对总可消化养分没有影响。
