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Environmental sustainability research at Harper Adams highlighted at two major international conferences

Posted 19 July 2022

Research on how to reduce the environmental impact and improve the health and welfare of dairy cows – which could also have a major impact on farming costs – has been presented at two international conferences.

Professor of Animal Science Liam Sinclair was invited to speak to 1500 farmers at the Danish Dairy Cattle and Beef conference in May on reducing the protein content and including forage legumes in the diet of dairy cows.

His findings were also presented at the American Dairy Science Association annual meeting in June to 1350 delegates in Kansas City, USA.

He said: “The environmental effects of over-feeding protein to dairy cows is that it can lead to an increased concentration of nitrates in water and release of nitrous oxide from slurry.

“More recently there has been a focus on ammonia emissions from dairy farms, which is mainly released from the cow’s urine. The ammonia reacts with acids in the air to produce fine particulate material - referred to as PM_2.5 - which can cause respiratory problems in humans.

“This is similar to the particles released from older diesel cars, and is why they are banned from many city centres. The recent changes in nitrogen legislation in the Netherlands and subsequent farmer demonstrations highlights how important this subject is.” 

Another aspect to the research at Harper Adams is the inclusion of home-grown forage legumes such as red clover.

Professor Sinclair added: “Red clover has two main advantages. Firstly, as a legume it fixes nitrogen from the atmosphere, reducing the requirement for artificial fertiliser.

“This improves whole-farm Nitrogen balance, and reduces input costs – which is important at the present moment, with the cost of artificial fertiliser increasing several-fold over the past 12 months.  

“Red clover is also high in protein at around 200 g/kg DM, compared with 140 g/kg DM in grass silage or 80 g/kg DM in maize silage. This reduces the need for expensive purchased feeds such as soyabean or rapeseed meal, reducing feed costs and insulating dairy farms from the volatility of world feed prices.”

The research at Harper Adams, which was funded by AHDB, has shown that the protein content of dairy cow rations can be reduced from around 175 to 150 g/kg DM without affecting cow performance if the diet is properly formulated to meet the requirements of the microbes in the rumen and the cow.

Professor Sinclair added: “This can reduce purchased feed costs by around 0.5 to 1ppl, and will reduce the amount of N excreted in the urine by around 20 kg/cow/year, or 50 kg N/ha when applied back to the land. These are both very exciting and important findings for dairy farmers.”

Whilst in Denmark, Professor Sinclair also presented research on the negative effects of over-feeding minerals such as phosphorus and copper on the environment and cow health.

He explained: “Our research has shown that most dairy farmers over-feed phosphorus, but this can be reduced without affecting performance and will reduce feed costs.

Over feeding minerals such as copper can also have a negative effect on cow health, fertility and performance.

“Our AHDB funded research is the first to demonstrate that UK dairy farmers are over-feeding copper, and that this is having a long-term negative effect on cow fertility, performance and health,” added Professor Sinclair.