van Gastelen Sanne, Dijkstra Jan, Heck Jeroen M L, Kindermann Maik, Klop Arie, de Mol Rudi, Rijnders Dennis, Walker Nicola, Bannink André
Wageningen Livestock Research, Wageningen University & Research, PO Box 338, 6700 AH, Wageningen, the Netherlands.
Animal Nutrition Group, Wageningen University & Research, PO Box 338, 6700 AH, Wageningen, the Netherlands.
J Dairy Sci. 2022 May;105(5):4064-4082. doi: 10.3168/jds.2021-20782. Epub 2022 Feb 25.
The objective of this study was to investigate whether the CH mitigation potential of 3-nitrooxypropanol (3-NOP) in dairy cattle was affected by basal diet (BD) composition. The experiment involved 64 Holstein-Friesian dairy cows (146 ± 45 d in milk at the start of trial; mean ± SD) in 2 overlapping crossover trials, each consisting of 2 measurement periods. Cows were blocked according to parity, d in milk, and milk yield, and randomly allocated to 1 of 3 diets: a grass silage-based diet (GS) consisting of 30% concentrates and 70% grass silage (DM basis), a grass silage- and corn silage-mixed diet (GSCS) consisting of 30% concentrates, 42% grass silage, and 28% corn silage (DM basis), or a corn silage-based diet (CS) consisting of 30% concentrates, 14% grass silage, and 56% corn silage (DM basis). Two types of concentrates were formulated, viz. a concentrate for the GS diet and a concentrate for the CS diet, to meet the energy and protein requirements for maintenance and milk production. The concentrate for the GSCS diet consisted of a 50:50 mixture of both concentrates. Subsequently, the cows within each type of BD received 2 treatments in a crossover design: either 60 mg of 3-NOP/kg of DM (NOP60) and a placebo with 0 mg of 3-NOP/kg of DM (NOP0) in one crossover or 80 mg of 3-NOP/kg of DM (NOP80) and NOP0 in the other crossover. Diets were provided as total mixed ration in feed bins, which automatically recorded feed intake. Additional concentrate was fed in the GreenFeed system that was used to measure emissions of CH and H. The CS diets resulted in a reduced CH yield (g/kg DMI) and CH intensity (g/kg milk). Feeding 3-NOP resulted in a decreased DMI. Milk production and composition did not differ between NOP60 and NOP0, whereas milk yield and the yield of major components decreased for NOP80 compared with NOP0. Feed efficiency was not affected by feeding 3-NOP. Interactions between BD and supplementation of 3-NOP were observed for the production (g/d) and yield (g/kg DMI) of both CH and H, indicating that the mitigating effect of 3-NOP depended on the composition of the BD. Emissions of CH decreased upon 3-NOP supplementation for all BD, but the decrease in CH emissions was smaller for GS (-26.2% for NOP60 and -28.4% for NOP80 in CH yield) compared with both GSCS (-35.1% for NOP60 and -37.9% for NOP80 for CH yield) and CS (-34.8% for NOP60 and -41.6% for NOP80 for CH yield), with no difference between the latter 2 BD. Emissions of H increased upon 3-NOP supplementation for all BD, but the H yield (g/kg DMI) increased 3.16 and 3.30-fold, respectively, when NOP60 and NOP80 were supplemented to GS, and 4.70 and 4.96 fold, respectively, when NOP60 and NOP80 were supplemented to CS. In conclusion, 3-NOP can effectively decrease CH emissions in dairy cows across diets, but the level of CH mitigation is greater when supplemented in a corn silage-based diet compared with a grass silage-based diet.
本研究的目的是调查3-硝基氧丙醇（3-NOP）对奶牛甲烷减排潜力是否受基础日粮（BD）组成的影响。该实验在2个重叠的交叉试验中涉及64头荷斯坦-弗里生奶牛（试验开始时产奶146±45天；平均值±标准差），每个试验由2个测量期组成。奶牛根据胎次、产奶天数和产奶量进行分组，并随机分配到3种日粮中的1种：以青贮牧草为基础的日粮（GS），由30%精饲料和70%青贮牧草（干物质基础）组成；青贮牧草和青贮玉米混合日粮（GSCS），由30%精饲料、42%青贮牧草和28%青贮玉米（干物质基础）组成；或以青贮玉米为基础的日粮（CS），由30%精饲料、14%青贮牧草和56%青贮玉米（干物质基础）组成。配制了两种类型的精饲料，即GS日粮用精饲料和CS日粮用精饲料，以满足维持和产奶的能量和蛋白质需求。GSCS日粮用精饲料由两种精饲料按50:50的比例混合而成。随后，每种BD类型的奶牛在交叉设计中接受2种处理：一种交叉处理为60毫克3-NOP/千克干物质（NOP60）和0毫克3-NOP/千克干物质的安慰剂（NOP0），另一种交叉处理为80毫克3-NOP/千克干物质（NOP80）和NOP0。日粮以全混合日粮的形式提供在饲料槽中，饲料槽自动记录采食量。额外的精饲料通过GreenFeed系统投喂，该系统用于测量甲烷和氢气的排放。CS日粮导致甲烷产量（克/千克干物质采食量）和甲烷强度（克/千克牛奶）降低。投喂3-NOP导致干物质采食量下降。NOP60和NOP0之间的产奶量和乳成分没有差异，而与NOP0相比，NOP80的产奶量和主要成分产量下降。投喂3-NOP对饲料效率没有影响。观察到BD和3-NOP添加之间在甲烷和氢气的产量（克/天）和产率（克/千克干物质采食量）方面存在相互作用，表明3-NOP的减排效果取决于BD的组成。对于所有BD，添加3-NOP后甲烷排放均减少，但与GSCS（NOP60时甲烷产量降低35.1%，NOP80时降低37.9%）和CS（NOP60时甲烷产量降低34.8%，NOP80时降低41.6%）相比，GS的甲烷排放减少幅度较小（NOP60时甲烷产量降低26.2%，NOP80时降低28.4%），后两种BD之间没有差异。对于所有BD，添加3-NOP后氢气排放均增加，但当向GS添加NOP60和NOP80时，氢气产率（克/千克干物质采食量）分别增加3.16倍和3.30倍，当向CS添加NOP60和NOP80时，氢气产率分别增加4.70倍和4.96倍。总之，3-NOP可以有效降低不同日粮奶牛的甲烷排放，但与以青贮牧草为基础的日粮相比，在以青贮玉米为基础的日粮中添加时甲烷减排水平更高。
