Department of Agriculture, Food and Nutritional Science, University of Alberta, 4-10 Agriculture Forestry Center, University of Alberta, Edmonton, AB T6G 2P5, Canada.
Department of Agriculture, Food and Nutritional Science, University of Alberta, 4-10 Agriculture Forestry Center, University of Alberta, Edmonton, AB T6G 2P5, Canada.
Animal. 2022 Apr;16(4):100491. doi: 10.1016/j.animal.2022.100491. Epub 2022 Mar 22.
Medium-chain fatty acids (MCFAs) have antimicrobial properties and cause negative or positive effects on animal performance depending on its dosage. We hypothesized that MCFA supplementation at a lower dose (i.e., 0.05-0.2% of dietary DM) would increase rumen pH and milk production without decreasing nutrient digestibility which is typically observed with the higher inclusion rates (i.e., >1% of dietary DM). The objective of this study was to evaluate the effects of MCFA supplementation at a lower dose on productivity, plasma energy metabolite concentrations, apparent total tract nutrient digestibility, rumen fermentation, and rumen microbial profile of lactating dairy cows. Thirty (n = 8 primiparous, n = 22 multiparous) Holstein cows in mid-lactation (637 ± 68.5 kg of initial BW, 98.5 ± 27.4 d in milk; mean ± standard deviation) were used in a crossover design with two 28-d periods. The MCFA supplement, consisted of 25% MCFA (containing 32% C8:0, 21% C10:0, 47% C12:0 on DM basis) and 75% carrier ingredients, was fed at 0.25% of dietary DM replacing dry ground corn in control (CON). Total inclusion of MCFA was 0.063% of dietary DM. No differences were observed in DM intake, apparent total tract nutrient digestibility and BW change between MCFA and CON. Milk and milk component yields did not differ between treatment groups. The MCFA supplementation tended to have higher minimum rumen pH (5.66 vs. 5.54), and decreased daily fluctuation range of rumen pH (1.17 vs. 1.40) compared to CON. However, the duration of acidosis (pH < 5.8, min/d) did not differ between treatment groups and ruminal total volatile fatty acid concentration and its profile did not differ between treatment groups. For rumen microbiota, the Chao1 index of bacterial community tended to be lower (10.9 vs. 11.6) whereas the Shannon index did not differ (0.91 vs. 0.93) in MCFA compared to CON, and both indices did not differ for archaeal and protozoan communities between treatment groups. The relative abundance of Methanobrevibacter gottschalkii increased when supplemented with MCFA (5.14 vs. 4.92%). These results suggest that supplementation of MCFA at 0.063% dietary DM may not affect overall animal performance or total tract nutrient digestibility, but decrease the daily range of pH and the bacterial richness in the rumen.
中链脂肪酸（MCFAs）具有抗菌特性，并根据其剂量对动物性能产生负面影响或积极影响。我们假设，在较低剂量（即日粮干物质的 0.05-0.2%）下补充 MCFA 将增加瘤胃 pH 值和产奶量，而不会降低通常在较高添加率（即>1%日粮干物质）下观察到的养分消化率。本研究的目的是评估在较低剂量下补充 MCFA 对泌乳奶牛生产性能、血浆能量代谢物浓度、表观全肠道养分消化率、瘤胃发酵和瘤胃微生物区系的影响。30 头（n=8 头初产，n=22 头经产）荷斯坦奶牛处于泌乳中期（初始 BW 为 637±68.5kg，泌乳天数为 98.5±27.4d；平均值±标准差），采用交叉设计进行试验，有两个 28d 期。MCFA 补充剂由 25%MCFA（DM 基础上含有 32%C8:0、21%C10:0、47%C12:0）和 75%载体成分组成，以 0.25%日粮干物质的形式添加，替代对照（CON）中的干磨玉米。MCFA 的总添加量为日粮干物质的 0.063%。MCFA 和 CON 之间在 DM 摄入量、表观全肠道养分消化率和 BW 变化方面没有差异。牛奶和牛奶成分产量在处理组之间没有差异。与 CON 相比，MCFA 组的瘤胃 pH 值最低（5.66 比 5.54）和瘤胃 pH 值日波动范围减小（1.17 比 1.40），但酸中毒持续时间（pH<5.8，min/d）在处理组之间没有差异，并且处理组之间瘤胃总挥发性脂肪酸浓度及其谱没有差异。对于瘤胃微生物群，细菌群落的 Chao1 指数趋于降低（10.9 比 11.6），而 Shannon 指数在 MCFA 与 CON 之间没有差异（0.91 比 0.93），并且处理组之间的古菌和原生动物群落的这两个指数没有差异。补充 MCFA 时，产甲烷菌属（Methanobrevibacter gottschalkii）的相对丰度增加（5.14 比 4.92%）。这些结果表明，在日粮干物质中添加 0.063%的 MCFA 可能不会影响动物的整体生产性能或全肠道养分消化率，但会降低瘤胃 pH 值的日波动范围和细菌丰富度。
