01/06/2015: Make stabilising rumen pH a priority to maintain grazing butterfats

Milk producers looking to maintain butterfats following turnout are being urged to focus on stabilising rumen pH in order to boost the supply of milk fat-precursors to the udder.

“Milk fat production is closely linked to the production of the volatile fatty acids (VFA) acetate and butyrate in the rumen, and they’re produced primarily by the microbes responsible for breaking down fibre,” explains Dr Derek McIlmoyle, AB Vista’s Technical Director for GB and Ireland.

         

Image: jenny downing

“Yet the efficiency of fibre breakdown is compromised any time rumen content drops below pH 5.8. Maintaining a stable rumen pH close to the pH 6.0 optimum should therefore be a top priority if you want to minimise the drop-off in butterfats seen when cows go out to grass.”

The challenge for milk producers is that the overall diet fed to most grazing cows supplemented with concentrates is low in fibre and high in rapidly available starch and sugars. Both factors not only promote the production of the VFA propionate at the expense of acetate and butyrate, but also produce a rapid and extensive drop in rumen pH.

“So, make sure there’s enough long fibre in the diet by increasing the forage-to-concentrate to at least 60:40, and include hay, baleage or chopped straw to stimulate cudding and the production of saliva,” Dr McIlmoyle advises.

“Treating home-grown cereals with caustic soda will further help buffer rumen pH, as will switching from starchy concentrates to those high in digestible fibre. Most cows will also respond to a slow-release rumen conditioner like Acid Buf or a metabolically active yeast, such as Vistacell, both of which can increase butterfats by several percentage points, or even more if used together.”

Visit the AB Vista website HERE. 

 

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