Changes

In the last 20 years, selective breeding and improved genetics have dramatically increased the individual cow's milk yield and hence the energy requirements for lactation. In order to meet these increased energy demands and avoid prolonged negative energy balance in early lactation, the energy density of the ration has also been increased. This has been achieved by feeding high levels of concentrate feed and energy-rich maize silage. Although these are effective in helping to meet energy requirements, they also contain large quantities of rapidly fermentable carbohydrates that cause increased production of acid in the rumen. The results in a fall in rumen pH below the optimum range of 6-7. This is known as subacute rumenal acidosis.  

In the last 20 years, selective breeding and improved genetics have dramatically increased the individual cow's milk yield and hence the energy requirements for lactation. In order to meet these increased energy demands and avoid prolonged negative energy balance in early lactation, the energy density of the ration has also been increased. This has been achieved by feeding high levels of concentrate feed and energy-rich maize silage. Although these are effective in helping to meet energy requirements, they also contain large quantities of rapidly fermentable carbohydrates that cause increased production of acid in the rumen. The results in a fall in rumen pH below the optimum range of 6-7. This is known as subacute rumenal acidosis.  

It is

Subacute rumenal acidosis is a herd problem that is often never recognised, let controlled. The defintion of the condition is "at least 30% of the herd have rumen pH values of less than 5.7 when sampled by rumenocentesis".

insidious and, in many cases is never recognised or

diagnosed. let alone prevented. It is a group problem and

bv a number of the g)rOup members having suboptimal

ruIllenl pH values. The deflinitioni applied in the USA is at

least 30 per cent of animials having rumen pH values of

5 5 or less when saimipled by ruIlmenlocentesis (Nordlund

SARA using this threshold.