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The role of the rumen microbiome in improving nitrogen use efficiency and reducing the environmental impact of dairy cows

Primary supervisor: Professor Liam A. Sinclair, Department of Agriculture and Environment

Non-academic partner: Alltech UK Ltd

Project Title: The role of the rumen microbiome in improving nitrogen use efficiency and reducing the environmental impact of dairy cows

Project description:

Currently only around 25% of the nitrogen (N) consumed by dairy cows is captured in milk, with the remaining 75% excreted in urine and faeces (Sinclair et al., 2014). This loss of N can contribute to the deterioration of terrestrial and aquatic ecosystems (Dijkstra et al., 2013; Whelan et al., 2013), and dairy farming is the major contributor to ammonia emissions in the UK (Defra, 2019). Ammonia is a gas that is emitted from cattle slurry and either deposited onto land, where it causes water eutrophication and soil acidification (Defra, 2019), or is converted to secondary fine particulate matter that can get into the lungs and blood of humans and animals where it is toxic (Li et al., 2017). There is also public interest in alternatives to feeding soybean meal due to its high environmental cost when grown in deforested regions (Henderson et al., 2021).

The rumen microbiome plays an essential role in feed digestion and N use in dairy cattle, supplying volatile fatty acids for energy use, and high quality microbial protein for host metabolism and performance (McDonald et al., 2021). Recent developments in evaluating microbial composition include marker based amplicon sequencing or metagenomics shotgun sequencing that provide a greater understanding of the composition and function of the rumen, and how the diet and microbiome interact (Zhou et al., 2021). This knowledge is fundamental to improving N use efficiency in dairy cows. The objectives of this project are to manipulate the rumen microbiome by dietary means to improve N use efficiency in dairy cows and consequently reduce N and ammonia-N excretion. A series of dairy cow and in vitro studies will be conducted where the diet will be manipulated and specific feed and forage additives used.

Harper Adams University is one of the few centres in Europe that has the capability to carry out high impact research investigating dietary effects on the rumen microbiome, microbial metabolism and N use efficiency in dairy cows. Lactating dairy cows fitted with rumen cannula allow direct access to the rumen digesta for sampling of the microbiome and the inoculation of in vitro systems. The rumen microbial community will be analysed using the most recent metagenomics and metabarcoding analysis, with blood, urine and faecal samples collected to examine the metabolic and N-balance response. Novel feeds, along with dietary and forage additives will be used to modify the microbiome and reduce or replace protein sources, such as soybean meal.

Contact: Professor Liam A. SinclairLink opens in a new window, Harper Adams University

To apply see the HAU websiteLink opens in a new window