ETH Zurich, Institute of Agricultural Sciences, Lindau, Switzerland.
Swiss College of Agriculture, Berne University of Applied Sciences, Zollikofen, Switzerland.
J Anim Physiol Anim Nutr (Berl). 2023 Jan;107(1):37-52. doi: 10.1111/jpn.13696. Epub 2022 Mar 5.
Dairy cows, methane and global warming have become publicly related terms. However, appropriate dairy cow management may in fact be part of the climate solution when viewed as part of the biogenic carbon cycle. Accordingly, governments and consumers are encouraging more sustainable, locally produced, climate friendly dairy production that often includes grassland-based feeding. However, this system is presumed to result in greater methane emissions compared to corn silage- or concentrate-based diets. An increase in urine nitrogen, associated with increased ammonia and nitrous oxide emission potential, questions the environmental usefulness of this strategy pertaining to global warming. This study is the first to compare the effects of incremental increases of grass silage proportion on enteric methane production as well as N and energy losses in dairy cows. Twenty-four mid- to end-lactation dairy cows were each fed one of 24 different diets, from two different harvest years, gradually increasing in grassland-based feeds (grass silage and hay) from about 500 to 1000 g/kg and concomitantly decreasing in corn silage. Each cow underwent a 7-day total collection period and was housed for 48 h in respiration chambers. Incremental data were subjected to an approved parametric regression analysis approach. The dietary increase in grassland-based feeds did not impair milk yield, N and energy utilisation. Simplified regression equations revealed that, contrary to current assumptions, there was a decline in methane production from 373 to 303 g/day when increasing grassland-based feeds from 500 to 1000 g/kg diet, and there was a trend for a decline in emission intensity from 20.6 to 17.6 g/kg of energy-corrected milk. However, urine nitrogen emissions clearly increased even when related to nitrogen intake; the latter from 260 to 364 g/kg when increasing grassland-based feeds from 500 to 1000 g/kg. Methane and urine nitrogen emissions were not affected by year of harvest.
奶牛、甲烷和全球变暖已经成为公众关注的相关术语。然而，从生物碳循环的角度来看，适当的奶牛管理实际上可能是气候解决方案的一部分。因此，政府和消费者鼓励更可持续、本地生产、对气候友好的奶牛生产，通常包括基于草地的饲养。然而，与基于玉米青贮或浓缩饲料的饮食相比，这种系统被认为会导致更大的甲烷排放。与增加的氨和一氧化二氮排放潜力相关的尿液氮增加，对这种与全球变暖相关的策略的环境有用性提出了质疑。本研究首次比较了逐渐增加基于草地的饲料（青贮和干草）比例对奶牛肠道甲烷产生以及氮和能量损失的影响。24 头处于泌乳中期至后期的奶牛，每头奶牛都喂食 24 种不同的饲料中的一种，这些饲料来自两个不同的收获年份，逐渐增加基于草地的饲料（青贮和干草），从约 500 至 1000 克/千克，同时减少玉米青贮的用量。每头奶牛进行了为期 7 天的总收集期，并在呼吸室中饲养了 48 小时。增量数据进行了经批准的参数回归分析方法处理。日粮中增加基于草地的饲料不会降低产奶量、氮和能量利用率。简化回归方程表明，与当前的假设相反，当饲料中基于草地的饲料从 500 克/千克增加到 1000 克/千克时，甲烷产量从 373 克/天下降到 303 克/天，而从 20.6 克/千克到 17.6 克/千克的能量校正奶的排放强度呈下降趋势。然而，即使与氮摄入量相关，尿液氮的排放量也明显增加；当从 500 克/千克增加到 1000 克/千克时，尿液氮的摄入量从 260 克/千克增加到 364 克/千克。甲烷和尿液氮的排放不受收获年份的影响。
