Beef School, Ep 11: Why ideal pH and optimal rumen function go hand in hand


It’s the dead of winter — do you know what your cattle’s rumen is up to? Chances are, cattle are wintering mainly on dry hay, with maybe some added straw to stretch hay supplies. When it comes to winter grazing and feeding, it’s important to take rumen pH levels and the impact a low pH can have on rumen function. Winter grazing can also mean added feed variability, and that variability could impact optimal rumen function.

On this episode of the RealAgriculture Beef School, Dr. Greg Penner, associate professor at the University of Saskatchewan (U of S), explains rumen function can be manipulated by many factors — including pH levels. He says his team of researchers at the U of S have connected low pH with a decrease in fibre digestibility.

“That’s important when we’re talking about winter feeding systems when our cattle are consuming mostly forage,” says Penner. Penner and his team have explored various aspects of winter feeding, including the impact of how pH impacts rumen microbes and thus the cow’s ability to digest fibre.

“We know when the pH level is too low for too long, we see the (rumen) microbes have more trouble digesting fibre,” Penner says. That reduced ability to use fibre means ranchers could be losing out on some of the benefit of having ruminants make the best use of  lower quality forages.

Even worse, Penner says from the breeding cow side of things, if the pH gets too low, it can damage the gastrointestinal tract — which is never good as it can induce an immune response and potentially damage the overall health and lifespan of the cow.

Now, to achieve optimal rumen function with pH, Penner says it’s actually changed quite a bit over the last 10 years.

“We now look at fibre in very different ways instead of just looking at the neutral detergent fibre component, we start looking at how fast that fibre is broken down as well as the starch components, or other non-structural carbohydrates as well as how rapidly they’re digested.”

With the technology currently available around feed formulation, he adds they’re able to balance the slowly digestible carbohydrates like forages with the rapidly digestible carbohydrates like cereal grains and sugars.

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