A successful transition is determined by getting the timing right. We need to be careful with our recording of calving dates. An accurate calving date record gives confidence when introducing the necessary salts in order to stimulate hormone release in the lead up to that all-important calving date.
Should you have any doubt around the accuracy of the calving date, there’s no harm in feeding a cow negative DCAD transition salts earlier, and for longer than normal. Starting too late, however, seriously compromises transition and risks a downer cow.
From around three weeks before calving to three weeks after calving, a cow’s diet, energy demand, and microbial balance all shift dramatically. How well her rumen adapts to these shifts can make or break her start to lactation.
Why the rumen matters in transition
The rumen isn’t just a holding tank, it’s a living ecosystem. Billions of microbes break down fibre and convert feed into the volatile fatty acids (VFAs) that fuel a cow’s energy needs. In late pregnancy, intake starts to drop off due to the calf taking up more space. Post-calving, she suddenly needs double the energy, and her appetite struggles to keep up.
If the rumen isn’t functioning well, feed intake drops even further, and energy deficits worsen. That’s when the trouble starts – fat mobilisation (ketosis), liver stress, milk production, immune function, and reproduction, can all have knock-on effects that compromise her health.
Transition time is also when the rumen microbes have to switch gears. If the pre-calving diet is high in fibre and the post-calving diet is high in fermentable energy, as is often the case in pasture-based systems, the sudden shift can throw the rumen out of balance. This is where rumen acidosis risk can spike.
Rumen health and subclinical acidosis
Sub-acute ruminal acidosis (SARA) can go unnoticed but undermines health on many farms during early lactation. Cows keep milking, keep walking to the paddock, and don’t show dramatic signs. But behind the scenes, low rumen pH suppresses fibre digestion, reduces feed efficiency, and produces endotoxins that compromise hoof health and weaken the immune system.
SARA also affects liver health. When the rumen wall is damaged, endotoxins leak into the bloodstream. The liver then has to work overtime to clear them, just when it’s already under pressure from fat breakdown and hormone cycling. This impacts everything from milk production to reproductive performance.
How minerals help support the rumen
This is where targeted mineral nutrition during transition really earns its keep. It’s not just about calcium and magnesium, it’s about supporting rumen stability, microbial activity, and nutrient absorption.
A product like Optiprill Rumen Plus includes a rumen buffer, which helps stabilise pH and reduces the risk of SARA during dietary shifts. It also provides sodium, magnesium, and high-quality trace minerals in prilled form – ideal for in-shed feeding systems and consistent daily intake.
Trace minerals such as cobalt, zinc, and copper support the rumen microbes and the rumen wall itself. Cobalt, for example, is vital for B12 synthesis, and B12 is essential for energy metabolism and red blood cell function. If the rumen can’t produce B12 efficiently, cows won’t convert feed to energy effectively, no matter how good the grass is.
Supporting smoother transitions with rumen in mind
Feeding for rumen health means more than just avoiding big diet shifts. It means thinking about how cows are adapting – microbially, metabolically, and behaviourally – to the seasonal changes in energy demand, forage quality, and calving stress play heavily into this.
Adding rumen-friendly minerals and buffers during pre- and post-calving supports better fibre digestion, steadier intakes, and stable rumen pH. This approach keeps cows on track, improves the efficiency of your feed, and reduces the risk of hitting trouble in early lactation.
A healthy rumen sets the stage for everything else to go right, and it’s one of the most practical, cost-effective ways to improve transition success without major overhauls.
To find out how you can support rumen health in your herd, talk to your local Agvance Consultant today.