Harper M T, Oh J, Giallongo F, Roth G W, Hristov A N
Department of Animal Science, The Pennsylvania State University, University Park 16802.
Department of Plant Science, The Pennsylvania State University, University Park 16802.
J Dairy Sci. 2017 Aug;100(8):6151-6163. doi: 10.3168/jds.2017-12553. Epub 2017 Jun 7.
The objective of this experiment was to partially replace corn silage with 2 alternative forages, wheat (Triticum aestivum) or triticale (X Triticosecale) silages at 10% of the diet dry matter (DM), and investigate the effects on dairy cow productivity, nutrient utilization, enteric CH emissions, and farm income over feed costs. Wheat and triticale were planted in the fall as cover crops and harvested in the spring at the boot stage. Neutral- and acid-detergent fiber and lignin concentrations were higher in the wheat and triticale silages compared with corn silage. The forages had similar ruminal in situ effective degradability of DM. Both alternative forages had 1% starch or less compared with the approximately 35% starch in corn silage. Diets with the alternative forages were fed in a replicated 3 × 3 Latin square design experiment with three 28-d periods and 12 Holstein cows. The control diet contained 44% (DM basis) corn silage. In the other 2 diets, wheat or triticale silages were included at 10% of dietary DM, replacing corn silage. Dry matter intake was not affected by diet, but both wheat and triticale silage decreased yield of milk (41.4 and 41.2 vs. 42.7 ± 5.18 kg/d) and milk components, compared with corn silage. Milk fat from cows fed the alternative forage diets contained higher concentrations of 4:0, 6:0, and 18:0 and tended to have lower concentrations of total trans fatty acids. Apparent total-tract digestibility of DM and organic matter was decreased in the wheat silage diet, and digestibility of neutral-and acid-detergent fiber was increased in the triticale silage diet. The wheat and triticale silage diets resulted in higher excretion of urinary urea, higher milk urea N, and lower milk N efficiency compared with the corn silage diet. Enteric CH emission per kilogram of energy-corrected milk was highest in the triticale silage diet, whereas CO emission was decreased by both wheat and triticale silage. This study showed that, at milk production of around 42 kg/d, wheat silage and triticale silage can partially replace corn silage DM and not affect DM intake, but milk yield may decrease slightly. For dairy farms in need of more forage, triticale or wheat double cropped with corn silage may be an appropriate cropping strategy.
本试验的目的是用两种替代饲草，即小麦（普通小麦）或小黑麦（× 小麦黑麦草）青贮料，以日粮干物质（DM）的10%替代玉米青贮料，并研究其对奶牛生产性能、养分利用率、肠道甲烷排放以及饲料成本下农场收入的影响。小麦和小黑麦在秋季作为覆盖作物种植，并在春季孕穗期收获。与玉米青贮料相比，小麦和小黑麦青贮料中的中性洗涤纤维、酸性洗涤纤维和木质素浓度更高。这些饲草的瘤胃干物质原位有效降解率相似。与玉米青贮料中约35%的淀粉含量相比，两种替代饲草的淀粉含量均为1%或更低。含替代饲草的日粮在一项重复的3×3拉丁方设计试验中投喂，试验为期三个28天周期，共有12头荷斯坦奶牛。对照日粮含有44%（基于干物质）的玉米青贮料。在另外两种日粮中，小麦或小黑麦青贮料以日粮干物质的10%添加，替代玉米青贮料。干物质采食量不受日粮影响，但与玉米青贮料相比，小麦和小黑麦青贮料均降低了牛奶产量（分别为41.4和41.2千克/天，而玉米青贮料组为42.7±5.18千克/天）和牛奶成分含量。饲喂替代饲草日粮的奶牛所产牛奶脂肪中，4:0、6:0和18:0的浓度较高，总反式脂肪酸浓度则有降低趋势。小麦青贮料日粮中干物质和有机物的表观全肠道消化率降低，小黑麦青贮料日粮中中性洗涤纤维和酸性洗涤纤维的消化率提高。与玉米青贮料日粮相比，小麦和小黑麦青贮料日粮导致尿尿素排泄量增加、牛奶尿素氮含量升高以及牛奶氮效率降低。每千克能量校正奶的肠道甲烷排放量在小黑麦青贮料日粮中最高，而小麦和小黑麦青贮料均降低了二氧化碳排放量。本研究表明，在牛奶产量约为42千克/天时，小麦青贮料和小黑麦青贮料可部分替代玉米青贮料干物质，且不影响干物质采食量，但牛奶产量可能会略有下降。对于需要更多饲草的奶牛场来说，小黑麦或小麦与玉米青贮料复种可能是一种合适的种植策略。
