Hokkaido Agricultural Research Center, National Agriculture and Food Research Organization (NARO), Sapporo, Hokkaido, 062-8555, Japan.
Institute of Livestock and Grassland Science, NARO, Nasushiobara, Tochigi, 329-2793, Japan.
J Dairy Sci. 2018 Jun;101(6):5092-5101. doi: 10.3168/jds.2017-13802. Epub 2018 Mar 8.
We evaluated the effects of different methods of conserving the total mixed ration (TMR) and processing hulled rice (Oryza sativa L.) on intake, digestion, ruminal fermentation, lactation performance, and nitrogen utilization in dairy cows. Eight multiparous Holstein cows (126 ± 19 d in milk) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of dietary treatments. The experimental diets used fresh TMR and ensiled TMR containing either dry-rolled (DR) hulled rice or steam-flaked (SF) hulled rice. The fresh TMR was prepared every morning. The ensiled TMR was prepared by baling fresh TMR and then sealing it with a bale wrapper; this was stored outdoors at 10 to 30°C for >4 mo. The method of grain processing did not affect the dry matter (DM) intake. The DM intake tended to be greater for ensiled TMR than for fresh TMR. Apparent total-tract DM digestibility and milk yield were increased by feeding ensiled TMR instead of fresh TMR and by replacing DR with SF. An interaction effect between the TMR conservation method and the grain processing method was detected for DM digestibility and milk yield; replacing DR with SF increased the DM digestibility and milk yield in cows fed fresh TMR, but this did not affect the cows fed ensiled TMR. The milk fat and lactose contents did not differ among dietary treatments. The milk protein concentration was higher for the cows fed SF processed hulled rice than those fed DR, but it was not influenced by the TMR conservation method. The ruminal total volatile fatty acid concentration was higher for the cows fed ensiled TMR compared with those fed fresh TMR, but it was not affected by the grain processing method. The molar proportion of acetate was decreased and propionate was increased by feeding ensiled TMR instead of fresh TMR and by replacing DR with SF. The concentrations of rumen ammonia N and plasma urea N were higher for the cows fed ensiled TMR than fresh TMR and were lower for SF than DR. Feeding ensiled TMR instead of fresh TMR increased the cows' urinary N excretion and decreased the retention N. Replacing DR with SF decreased the urinary N excretion, increased the milk N secretion, and then improved the nitrogen efficiency. These results show that feeding ensiled TMR instead of fresh TMR has an adverse effect on N utilization, but it increases digestion and milk production. Replacing DR with SF also increases digestion, milk yield, and milk protein content, and the improvement of milk yield by replacing DR with SF was prominent in the cows fed fresh TMR.
我们评估了不同的全混合日粮（TMR）保存方法和加工整粒糙米（Oryza sativa L.）对奶牛采食量、消化、瘤胃发酵、泌乳性能和氮利用的影响。8 头经产荷斯坦奶牛（泌乳期 126±19 天）采用重复 4×4 拉丁方设计，日粮处理采用 2×2 因子设计。实验日粮使用新鲜 TMR 和青贮 TMR，其中含有干压（DR）整粒糙米或蒸汽压片（SF）整粒糙米。新鲜 TMR 每天早上制备。青贮 TMR 通过打包新鲜 TMR 并用捆包包装密封；在 10 到 30°C 的室外储存超过 4 个月。谷物加工方法不影响干物质（DM）摄入量。青贮 TMR 的 DM 摄入量往往大于新鲜 TMR。用青贮 TMR 代替新鲜 TMR 和用 SF 代替 DR 可以提高表观全肠道 DM 消化率和产奶量。TMR 保存方法和谷物加工方法之间存在 DM 消化率和产奶量的互作效应；用 SF 代替 DR 增加了采食新鲜 TMR 的奶牛的 DM 消化率和产奶量，但对采食青贮 TMR 的奶牛没有影响。奶牛的乳脂和乳糖含量在日粮处理之间没有差异。采食 SF 加工糙米的奶牛的乳蛋白浓度高于采食 DR 的奶牛，但不受 TMR 保存方法的影响。与采食新鲜 TMR 的奶牛相比，采食青贮 TMR 的奶牛瘤胃总挥发性脂肪酸浓度更高，但不受谷物加工方法的影响。用青贮 TMR 代替新鲜 TMR 和用 SF 代替 DR 可以降低乙酸摩尔比例，增加丙酸摩尔比例。采食青贮 TMR 的奶牛瘤胃液氨氮和血浆尿素氮浓度高于采食新鲜 TMR 的奶牛，SF 组低于 DR 组。用青贮 TMR 代替新鲜 TMR 增加了奶牛的尿氮排泄，降低了氮保留量。用 SF 代替 DR 降低了尿氮排泄，增加了乳氮分泌，从而提高了氮效率。这些结果表明，用青贮 TMR 代替新鲜 TMR 会对氮利用产生不利影响，但会增加消化和产奶量。用 SF 代替 DR 也会增加消化、产奶量和乳蛋白含量，用 SF 代替 DR 对采食新鲜 TMR 的奶牛的产奶量提高更为显著。
