USDA-ARS, Plant Science Research Unit and US Dairy Forage Research Center Cluster, St Paul, MN 55108, USA.
J Dairy Sci. 2011 Oct;94(10):5124-37. doi: 10.3168/jds.2011-4495.
Cross-linking of lignin to arabinoxylan by ferulates limits in vitro rumen digestibility of grass cell walls. The effect of ferulate cross-linking on dry matter intake (DMI), milk production, and in vivo digestibility was investigated in ad libitum and restricted-intake digestion trials with lambs, and in a dairy cow performance trial using the low-ferulate sfe corn mutant. Silages of 5 inbred corn lines were fed: W23, 2 W23sfe lines (M04-4 and M04-21), B73, and B73bm3. As expected, the W23sfe silages contained fewer ferulate ether cross-links and B73bm3 silage had a lower lignin concentration than the respective genetic controls. Silages were fed as the sole ingredient to 4 lambs per silage treatment. Lambs were confined to metabolism crates and fed ad libitum for a 12-d adaptation period followed by a 5-d collection period of feed refusals and feces. Immediately following the ad libitum feeding trial, silage offered was limited to 2% of body weight. After a 2-d adaptation to restricted feeding, feed refusals and feces were collected for 5 d. Seventy Holstein cows were blocked by lactation, days in milk, body weight, and milk production and assigned to total mixed ration diets based on the 5 corn silages. Diets were fed for 28 d and data were collected on weekly DMI and milk production and composition. Fecal grab samples were collected during the last week of the lactation trial for estimation of feed digestibility using acid-insoluble ash as a marker. Silage, total mixed ration, feed refusals, and fecal samples were analyzed for crude protein, starch, neutral detergent fiber (NDF), cell wall polysaccharides, and lignin. The W23sfe silages resulted in lower DMI in the ad libitum trial than the W23 silage, but DMI did not differ in the restricted trial. No differences were observed for NDF or cell wall polysaccharide digestibility by lambs with restricted feeding, but the amount of NDF digested daily increased for lambs fed the M04-21 W23sfe silage ad libitum. Lambs were less selective against NDF and lignin when offered W23sfe silages. The B73bm3 silage did not affect DMI or digestibility of cell walls at the restricted feeding level, but total daily NDF digested was greater at ad libitum intake. Intake, milk production, and cell wall digestibility were greater for cows fed diets containing W23sfe silages than for those fed W23 silage. Although milk production was greater for the B73bm3 diet, DMI and cell wall digestibility were not altered. Cows were less selective against cell wall material when fed both W23sfe and B73bm3 silages. Reduced ferulate cross-linking in sfe corn silage is a new genetic mechanism for improving milk production.
木质素与阿魏酸阿拉伯木聚糖的交联通过木质素限制了体外瘤胃消化率。通过绵羊的自由采食和限制采食消化试验以及低阿魏酸 sfe 玉米突变体的奶牛生产性能试验，研究了木质素阿魏酸交联对干物质采食量（DMI）、产奶量和体内消化率的影响。用 5 个自交系玉米品种的青贮料进行了青贮试验：W23、2 个 W23sfe 系（M04-4 和 M04-21）、B73 和 B73bm3。正如预期的那样，W23sfe 青贮料中的木质素阿魏酸醚交联较少，而 B73bm3 青贮料的木质素浓度低于各自的遗传对照。将青贮料作为唯一成分喂给每个青贮料处理的 4 只绵羊。绵羊被限制在代谢箱中，自由采食 12 天适应期，然后是 5 天的饲料拒绝和粪便收集期。在自由采食试验结束后，立即将提供的青贮料限制在体重的 2%。适应限制饲养 2 天后，收集 5 天的饲料拒绝和粪便。70 头荷斯坦奶牛按泌乳、泌乳天数、体重和产奶量进行分组，并根据 5 种玉米青贮料分配全混合日粮。日粮饲喂 28 天，每周收集干物质采食量和产奶量及组成数据。在泌乳试验的最后一周收集粪便抓样，用酸不溶性灰分作为标记估计饲料消化率。青贮料、全混合日粮、饲料拒绝物和粪便样品用于分析粗蛋白、淀粉、中性洗涤纤维（NDF）、细胞壁多糖和木质素。W23sfe 青贮料在自由采食试验中的 DMI 低于 W23 青贮料，但在限制采食试验中没有差异。限制采食的绵羊对 NDF 或细胞壁多糖消化率没有差异，但自由采食 M04-21 W23sfe 青贮料的绵羊每天消化的 NDF 量增加。当提供 W23sfe 青贮料时，绵羊对 NDF 和木质素的选择性较低。B73bm3 青贮料在限制饲养水平上不影响 DMI 或细胞壁的消化率，但自由采食时每日消化的总 NDF 量增加。与饲喂 W23 青贮料的奶牛相比，饲喂 W23sfe 青贮料的奶牛的采食量、产奶量和细胞壁消化率更高。虽然 B73bm3 日粮的产奶量更高，但 DMI 和细胞壁消化率没有改变。饲喂 W23sfe 和 B73bm3 青贮料的奶牛对细胞壁物质的选择性较低。sfe 玉米青贮料中木质素阿魏酸交联的减少是提高产奶量的一种新的遗传机制。
