Beauchemin K A, McGinn S M, Benchaar C, Holtshausen L
Agriculture and Agri-Food Canada, Lethbridge, Alberta, T1J 4B1, Canada.
J Dairy Sci. 2009 May;92(5):2118-27. doi: 10.3168/jds.2008-1903.
The objective of this study was to investigate the potential of reducing enteric methane production from dairy cows by incorporating into the diet various sources of long-chain FA varying in their degree of saturation and ruminal availability. The experiment was conducted as a crossover design with 16 lactating dairy cows maintained in 2 groups and fed 4 dietary treatments in four 28-d periods. Eight ruminally cannulated primiparous cows (96 +/- 18 d in milk) were assigned to group 1 and 8 multiparous cows (130 +/- 31 d in milk) were assigned to group 2. The dietary treatments were: 1) a commercial source of calcium salts of long-chain fatty acids (CTL), 2) crushed sunflower seeds (SS), 3) crushed flaxseed (FS), and 4) crushed canola seed (CS). The oilseeds added 3.1 to 4.2% fat to the diet (DM basis). All 3 oilseed treatments decreased methane production (g/d) by an average of 13%. When corrected for differences in dry matter intake (DMI), compared with CTL, methane production (g/kg of DM intake) was decreased by feeding FS (-18%) or CS (-16%) and was only numerically decreased (-10%) by feeding SS. However, compared with the CTL, feeding SS or FS lowered digestible DMI by 16 and 9%, respectively, because of lowered digestibility. Thus, only CS lowered methane per unit of digestible DM intake. Feeding SS and CS decreased rumen protozoal counts, but there were no treatment effects on mean ruminal pH or total volatile fatty acid concentration. Milk efficiency (3.5% fat corrected milk/DMI), milk yield, and component yield and concentrations were not affected by oilseed treatments. The study shows that adding sources of long-chain fatty acids to the diet in the form of processed oilseeds can be an effective means of reducing methane emissions. However, for some oilseeds such as SS or FS, the reduction in methane can be at the expense of diet digestibility. The use of crushed CS offers a means of mitigating methane without negatively affecting diet digestibility, and hence, milk production.
本研究的目的是通过在日粮中添加不同饱和度和瘤胃可利用性的各种长链脂肪酸来源，研究降低奶牛肠道甲烷产生的潜力。试验采用交叉设计，将16头泌乳奶牛分为2组，在4个28天的周期内饲喂4种日粮处理。8头瘤胃插管的初产奶牛（产奶96±18天）被分配到第1组，8头经产奶牛（产奶130±31天）被分配到第2组。日粮处理包括：1）长链脂肪酸钙盐的商业来源（CTL），2）碾碎的向日葵籽（SS），3）碾碎的亚麻籽（FS），4）碾碎的油菜籽（CS）。这些油籽使日粮中的脂肪含量增加了3.1%至4.2%（干物质基础）。所有3种油籽处理均使甲烷产量（克/天）平均降低了13%。在对干物质采食量（DMI）差异进行校正后，与CTL相比，饲喂FS（-18%）或CS（-16%）可降低甲烷产量（克/千克干物质采食量），而饲喂SS仅使甲烷产量在数值上有所降低（-10%）。然而，与CTL相比，饲喂SS或FS分别使可消化干物质采食量降低了16%和9%，原因是消化率降低。因此，只有CS降低了每单位可消化干物质采食量的甲烷产量。饲喂SS和CS可降低瘤胃原虫数量，但对平均瘤胃pH值或总挥发性脂肪酸浓度没有处理效应。乳效率（3.5%脂肪校正乳/DMI）、产奶量以及成分产量和浓度不受油籽处理的影响。该研究表明，以加工油籽的形式在日粮中添加长链脂肪酸来源可以是减少甲烷排放的有效手段。然而，对于某些油籽，如SS或FS，甲烷的减少可能以日粮消化率为代价。使用碾碎的CS提供了一种减轻甲烷排放而又不会对日粮消化率以及产奶量产生负面影响的方法。
