Willow (Salix spp): The potential of a tannin-rich tree fodder to reduce ammonia emissions and improve productivity of dairy cattle

柳树（Salix spp）：富含单宁的树饲料在减少氨排放和提高奶牛生产力方面的潜力

• 批准号: 2643190
• 金额: --
• 依托单位: Queen's University Belfast
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2643190
• 关键词: Willow; Salix; spp; potential; tannin

As the global demand for animal products is rising, these should be produced with less environmental impact. Climate-induced shifts increase feed costs due to increased need for resources (land and water). However, protein is poorly utilized by ruminant livestock and 20-35% of ingested N is excreted via urine and faeces. Therefore, alternative feeds associated with reduce competition for land and constitute industry by-products, are required. Willow (Salix sp.) fodder is used in biofuel production but leaves and branches, up to 18mm diameter, are considered as waste. Willow fodder tree has a high protein content (well above from that required for livestock maintenance) and contains condensed tannins (CT) which bind to proteins, reduce their ruminal degradation and shift N excretion from urine to faeces (environmentally friendly N form). Although willows fodder shows good potential in animal nutrition, data on its nutritive value are scarce. The aim of this project is to evaluate the nutritive value of willow and assess its potential to improve N use efficiency in dairy cows; by also assessing its impact on milk quality. This will be achieved via the following studies: 1. In vitro assessment of the effects of willow CT on rumen digestive capacity. Different willow varieties will be screened using the ANKOM Gas Production System. Measurements include: gas production/composition, fermentation of end products (VFA/ammonia) (QUB), biochemical profile (QUB), and CT quantification and profiling (URE). 2. Optimization of the ensiling process. Two willow varieties with the most potent ammonia inhibitory properties (study 1) will be selected. Raw material will be harvested in two seasons and willow silage (WS), with or without inoculum, will be prepared and stored for 3 months. The most efficient ensiling method will be used for the production of fodder for the animal trials (QUB). 3. Assessment of the effect of WS inclusion in the diet of dairy cow and ammonia emissions. A dairy cow trial will be contacted at AFBI, including the following assessments: (1) Determination of optimum replacement rates of grass silage. The inclusion rates of 2 WSs will be gradually increased with an interval of 7 days until a maximum inclusion rate is determined. (2) Quantifying the effect of WS inclusion on feed intake, milk production, nutrient digestibility, energy/N utilisation efficiency and CH4 emissions. Twelve lactating dairy cows, in a 3(diets)*3 (periods) Latin-Squared design, will be blocked into 4 groups of 3 cows based on live weight, body condition score, parity, lactation stage and milk production. Cows will be randomly allocated, within each group, into 3 diets: control (no WS) and 2 diets (50% and 100% of the maximum level). Each period will include a feeding phase of 19 days in cubicle accommodation, followed by a 9-day digestibility/chamber measurements (6-day period in individual metabolism units plus a 3-day period in indirect open-circuit respiration chambers). Feed intake and faecal/urine outputs will be measured in the final 8 days, while gaseous exchange will be measured on the final 2 days in chambers. (3) Measurement of ammonia emission rate from slurry. A sub-sample of faeces/urine collected during the digestibility/measurement phase will be placed in respiration calorimeter chambers for 2 days to measure ammonia in two different temperatures (5, 200C; to simulate winter and summer temperatures). 4. Reveal how rumen microbes influence metabolic pathways related to N use efficiency and milk quality. Basic milk composition analysis (QUB), FA profiling (URE), metagenomics (QUB) and 500MHz NMR-based metabolomics techniques (URE) using samples from the animal trial will be used to identify rumen microbes, their genes, and relevant metabolic pathways, which promote N use efficiency and milk quality.

随着全球对动物产品的需求不断增加，这些产品的生产应该减少对环境的影响。气候变化引起的变化增加了饲料成本，因为对资源（土地和水）的需求增加。然而，反刍家畜对蛋白质的利用率很低，20-35%的摄入氮通过尿液和粪便排出。因此，需要与减少土地竞争和构成工业副产品相关的替代饲料。杨柳（Salix sp.）饲料用于生物燃料生产，但直径达18毫米的树叶和树枝被视为废物。杨柳饲料树具有高蛋白质含量（远高于家畜饲养所需的含量），并含有与蛋白质结合的缩合单宁（CT），减少蛋白质的瘤胃降解，并将N排泄物从尿液转移到粪便（环境友好的N形式）。尽管柳树饲料在动物营养方面显示出良好的潜力，但关于其营养价值的数据却很少。本项目的目的是评估杨柳的营养价值，并评估其提高奶牛氮利用率的潜力，同时评估其对牛奶质量的影响。这将通过以下研究来实现：1。体外评价杨柳CT对瘤胃消化能力的影响。不同的杨柳品种将使用ANKOM气体生产系统进行筛选。测量包括：气体产生/组成、终产物发酵（VFA/氨）（QUB）、生物化学特征（QUB）和CT定量和特征（URE）。2.青贮过程的优化。将选择具有最有效的氨抑制特性的两个杨柳品种（研究1）。将在两个季节收获原材料，并制备含或不含接种物的杨柳青贮饲料（WS）并储存3个月。最有效的青贮方法将用于动物试验（QUB）饲料的生产。3.奶牛日粮中添加WS的效果和氨排放的评估。将在AFBI进行奶牛试验，包括以下评估：（1）确定青贮饲料的最佳替代率。2个WS的入选率将以7天的间隔逐渐增加，直至确定最大入选率。(2)量化添加WS对采食量、产奶量、养分消化率、能量/氮利用效率和CH 4排放的影响。根据活重、身体状况评分、胎次、泌乳期和产奶量，将12头泌乳奶牛按照3（日粮）× 3（阶段）拉丁方设计分为4组，每组3头奶牛。将每组内的奶牛随机分配至3种饲料中：对照（无WS）和2种饲料（最大水平的50%和100%）。每个阶段将包括在小隔间中19天的喂养阶段，然后是9天的消化率/腔室测量（在单个代谢单元中的6天阶段加上在间接开路呼吸腔室中的3天阶段）。将在最后8天测量摄食量和粪便/尿液排出量，而将在最后2天在室内测量气体交换。(3)泥浆中氨排放速率的测定。将在消化率/测量阶段收集的粪便/尿液子样本置于呼吸量热计室中2天，以在两种不同温度（5，200 ℃;模拟冬季和夏季温度）下测量氨。4.揭示瘤胃微生物如何影响与氮利用效率和牛奶品质相关的代谢途径。基础乳成分分析（QUB）、FA分析（URE）、宏基因组学（QUB）和基于500 MHz NMR的代谢组学技术（URE）将使用来自动物试验的样品来鉴定瘤胃微生物、它们的基因和相关代谢途径，这些代谢途径促进N利用效率和乳品质。