Nyløy Emma, Prestløkken Egil, Eknæs Margrete, Eikanger Katrine Sømliøy, Heldal Hagen Live, Kidane Alemayehu
Department of Animal and Aquacultural Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, 1430 Ås, Norway.
Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1430 Ås, Norway.
Animals (Basel). 2023 Jan 31;13(3):489. doi: 10.3390/ani13030489.
The current study assessed the effects of red macroalgae (AT)-included as an enteric methane inhibitor-in dairy cow diets on feed intake and eating-rumination behaviour. Fifteen early lactating Norwegian Red dairy cows were offered ad libitum access to drinking water and a total mixed ration (TMR) composed of 35% concentrate feed and 65% grass silage on a dry matter (DM) basis. The experiment lasted for 74 days with the first 22 days on a common diet used as the covariate period. At the end of the covariate period, the cows were randomly allocated into one of three dietary treatments: namely, 0% AT (control), 0.125% AT and 0.25% AT in the TMR. The TMR was offered in individual feed troughs with AT blended in a 400 g (/) water-molasses mixture. Eating-rumination behaviour was recorded for 11 days using RumiWatchSystem after feeding the experimental diets for 30 days. The 0.25% AT inclusion significantly reduced the DM intake (DMI). Time (min/d) spent on eating and eating in a head-down position increased with the increasing AT level in the diet, whereas rumination time was not affected. The greater time spent on eating head-down with the 0.25% AT group resulted in a significantly higher chewing index (min/kg DMI). Estimated saliva production per unit DMI (L/kg DMI, SE) increased from 10.9 (0.4) in the control to 11.3 (0.3) and 13.0 (0.3) in the 0.125% and 0.25% AT groups, respectively. This aligned with the measured ruminal fluid pH (6.09, 6.14, and 6.37 in the control, 0.125% AT and 0.25% AT groups, respectively). In conclusion, either the level of the water-molasses mixture used was not sufficient to mask the taste of AT, or the cows used it as a cue to sort out the AT. Studies with relatively larger numbers of animals and longer adaptation periods than what we used here, with varied modes of delivery of the seaweed may provide novel strategies for administering the additive in ruminant diets.
本研究评估了在奶牛日粮中添加红大型海藻（AT）作为肠道甲烷抑制剂对采食量和采食-反刍行为的影响。15头挪威红牛初产奶牛可自由饮水，并提供一种全混合日粮（TMR），按干物质（DM）计算，该日粮由35%的精饲料和65%的青贮牧草组成。实验持续74天，前22天采用普通日粮作为协变量期。在协变量期结束时，奶牛被随机分为三种日粮处理之一：即TMR中AT含量为0%（对照）、0.125%和0.25%。TMR通过单独的食槽提供，AT与400克（/）水-糖蜜混合物混合。在饲喂实验日粮30天后，使用瘤胃监测系统记录采食-反刍行为11天。添加0.25%的AT显著降低了干物质采食量（DMI）。随着日粮中AT水平的增加，采食时间（分钟/天）和低头采食时间增加，而反刍时间不受影响。0.25%AT组低头采食时间更长，导致咀嚼指数（分钟/千克DMI）显著更高。每单位DMI估计唾液分泌量（升/千克DMI，标准误）从对照组的10.9（0.4）分别增加到0.125%和0.25%AT组的11.3（0.3）和13.0（0.3）。这与测得的瘤胃液pH值一致（对照组、0.125%AT组和0.25%AT组分别为6.09、6.14和6.37）。总之，要么所用的水-糖蜜混合物水平不足以掩盖AT的味道，要么奶牛将其作为筛选出AT的线索。与我们这里使用的相比，采用数量相对较多的动物和更长适应期、不同海藻投喂方式的研究可能会为反刍动物日粮中添加该添加剂提供新策略。
