In November 2016, at the Nuffield Farming Trust Annual Conference, I was presented as one of the 2017 Nuffield Farming Scholars. The subject that I chose to study was entitled Increasing Rumen Nitrogen Efficiency in UK Dairy Production’.
The last two years have flown by!! In 18 months, I visited 14 countries and boarded 45 flights. With all my travelling done, and the report handed in, waiting to be published, I’m looking forward to sharing my thoughts and findings with the industry. In advance of the published article, I am very happy to share with you this introduction to explain my reasons, findings and conclusions from the report.
As a dairy farmer working within the feed industry, I was constantly frustrated by looking at unbalanced formulated diets which could be damaging to the health of the cow, the farmer’s pocket and the environment. Crude Protein (CP) is the industry standard figure to express the level of protein within a diet; CP is only a measure of the nitrogen (N) multiplied by 6.25.
Research shows that only 30% of the nitrogen (protein) that we feed ruminants is actually utilised by the animal and converted into milk or meat (O,Donovan et al, 2013). The rest is lost, either in the urine, faeces, or as urea within the milk; this can then be lost as ammonia to the atmosphere. The N contained in urine is very volatile and can be easily converted from ammonia to the more potent greenhouse gas nitrous oxide, and this poses huge environmental challenges.
The key objectives of my report were to research and evaluate how to formulate low protein diets and maintain, or increase, production through increasing rumen N efficiency and capturing more of the N we feed by converting it into a saleable protein product. This reduces the need to purchase expensive protein inputs which can be one of the highest costs on a dairy farm. Having a balanced diet would increase cow health and fertility, as well as increasing environmental sustainability by reducing the risk of ammonia emissions.
During this study I travelled to the USA, Canada, the Netherlands, Dubai, Australia, New Zealand and Ireland, visiting research institutions, meeting dairy nutritionists and consultants, along with visiting dairies from large housed herds, to fully grass based herds.
My report highlights some key conclusion to meet the objectives of my study. The UK dairy industry needs to be proactive in reducing ammonia emissions. Total N farm efficiency needs to be looked at in greater detail but reducing N emissions through lower CP diets will be a great start.
As an industry we need to get away from formulation diets to crude protein and feed for the requirement of what the cow can actually utilise, this being Amino Acids. In most UK scenarios there is enough N within the rumen and fermentable carbohydrates are the limiting factor in microbial protein synthesis. We can lower CP within our diets and increase carbohydrates, but first we need to understand fi bre and produce lower lactic acid silages.
Our UK dairy diets are predominantly based on perennial ryegrass which is either grazed or ensiled, but do we truly understand how the fibre (NDF) within grass breaks down within the rumen, and how does this differ depending on harvest dates through the season? During my time at Cornell University, I came across a new analytical method to measure NDF breakdown.
NDF and its digestibility plays a huge role in determining dry matter intake (DMI). A faster disappearance of the NDF fraction within the rumen, because of the increased rate of digestion or passage, will reduce physical fill in the rumen over time and promote higher feed intake. This shows that digestibility of NDF can influence performance of growth and milk yield even if NDF levels are similar in diets.
NDF can be broken down into three ‘pools’. NDF which hasn’t been degraded within 240 hours will be classified as uNDF (indigestible NDF), with the remainder digestible, and is available for the rumen microbes. This can be broken down into two further pools; fast pool and slow pool. Certain time points of degradability, depending on the feed material, will determine the pool within each forage.
The report emphasises the need for more accurate feed analysis of our forages to help understand our fibre, and how it changes through the season. If we understand our fibre we can increase fermentable carbohydrates within the diet andand assist in achieving higher microbial protein yield. This can help increase rumen N efficiency and reduce secreted N.
To further increase environmental sustainability of dairy farming we need to look at increasing feed efficiency to get more out of what we put in. Looking at management and breeding policies is key to achieving higher feed efficiency.
During my time in Green Bay, Wisconsin, I visited a 6,000 cowherd, milking crossbreds on an all-year-round indoor system. The herd had the influence of 2/3 Holstein genetics and 1/3 US Jersey genetics. Here I found two herds differing genetically and producing similar yield at very different efficiency rates (See Table 1). The crossbred herd achieved lower yields but equal MS output from 2.5kg less DM/cow.
Wherever I’ve been across the world, I realise that efficiency of production comes from homegrown forage. We need to realise the potential of your own farms to produce feed and increase DM yields before purchasing feed in the form of forage or concentrates onto farms. Looking at soil management and health can improve DM yields and reduce farm input costs.
As a proud UK dairy producer, I am determined to improve the public perception and environmental sustainability of UK dairy farming and hope this report will assist in addressing some of these issues for both farm and industry. The report will be published shortly so keep an eye out!!