Acid test

A wireless pH sensor that monitors the acidity of a cow's stomach from within the body has been developed by a group of UK animal and technology researchers. They hope the device will improve the diets of herds and reduce the methane they release.

Well Cow, a collaboration between Edinburgh animal research centre the Roslin Institute and The Technology Partnership of Cambridge, are testing the monitors with herds in the UK, US and Australia.

The sensor, encased in a pill that is swallowed by the cow, is weighted to the bottom of its stomach and remains in the rumen reticulum, the lowest of its four stomach compartments, for the rest of its life. The sensor is recovered after the cow dies.

Chas Sims, the director of The Technology Partnership and Well Cow, said the sensor's batteries last about two months during which time it will provide continuous information via radio communication on the changes of pH levels inside the cow's stomach. 'So when you go up to the sensor with a receiver it will establish communication and download the data,' he said.

The pH level of a cow's rumen is an important indicator of its health and productivity. The optimum environment for bacteria in the stomach and fibre digestion is a pH of 6.0 to 6.4. A lower, abnormal pH level can be harmful. Sims said that knowing a cow's pH levels in the rumen can help head off rumen acidosis, or high forestomach acidity, which can result when cattle are fed a diet with a high rate of cereals relative to an insufficient amount of forage.

The acidity of the rumen can increase so much that it affects bacteria, especially those that break down fibre. This will result in reduced digestibility of feed, lower feed intake, a reduction in milk fat and, as a result, a reduction in the cow's milk yield for the entire year.

Making sure that all cows maintain optimum milk production has financial and environmental advantages, said Sims. Ruminant livestock have been shown to produce up to 500 litres of methane a day, making them a significant contributor to global warming. It is estimated that cows produce 25 per cent of the UK's methane.

'If a cow's milk production is significantly destroyed for a whole year and if that happens across the whole UK, then clearly we need a lot more cows to produce the milk that we want to consume,' he said. 'But if you want less methane, then you want fewer cows to produce the milk that you need.'

Sims said pH monitoring can lead to better diets for cows, which means an increase in the amount of milk they produce and a decrease in the amount of methane they excrete.

While this sensor is only being used to research optimum diet for cattle, Sims said Well Cow is also considering using sensors in different areas. The company believes its technology has the potential to deliver the automated detection and measurement of fertility problems such as ovarian dysfunction, production diseases such as mastitis and infectious diseases like TB.

'There is a general trend in the agricultural world to want to automate many of these things because farms are getting bigger and it's more difficult for farmers to keep an eye on their cattle,' he said.

Sims added that his Technology Partnership is involved in another cattle sensor programme with ITI Techmedia, one of the three Scottish Enterprise-funded intermediary technology institutes. That project will develop sensors which monitor behavioural and physiological conditions of beef and dairy cows, including fertility and pregnancy.

A number of research studies have found that content cows produce higher levels of omega-3 fats, which in turn leads to the production of better tasting, more nutritious milk.