Watch out for acid loading in winter TMRs

03 Dec 2018

Early forage analyses suggest the acid loading effect of many grass and maize silages will be high in TMRs this winter. 

“While many grass silages have a higher overall D-value this year, they also have a set of characteristics that could make them difficult to utilise effectively,” says FiveF Alka’s Robert Cockroft.

Excess acidity

“With high levels of fermentable carbohydrate, care will be needed when feeding these grass silages. Not only are they already acidic, but they are also likely to digest more like a concentrate feed and create even more excess acidity in the rumen,” he says.

“And maize silages, while looking good overall, could be low in lignin while also containing a high level of fermentable carbohydrate. This will also contribute to acid loading in dairy-cow diets.”

Increasing intakes

Mr Cockroft says that this underlying acid load could act as an anchor on farms trying to cut feed costs, unless it is addressed within a TMR. “Whatever combination of increased yield or lower concentrate use is being pursued, success can only be achieved by increasing intakes and digestion of the forage components of the diet. And to do that you must limit the excess ration acidity load.”

Alkalisation of the TMR before it is fed to the cow helps to address this issue. “For example, when added to damp forage sources, AlkabupHa pellets rapidly release ammonia to neutralise excess acid in the diet,” says Mr Cockroft. “Dietary inclusion will improve rumen performance and boost dry matter intake, as well as contribute extra protein and macro minerals to the cow ration.