Phosphorous: why the right balance in your cows’ diet is crucial

17 March 2021
5 minutes

Making sure your dairy cows get the right nutritional balance can help improve your herd’s long-term health as well as your farm’s financial performance.

A well-timed Dietary Cation-Anion Difference (DCAD) strategy is widely proven to reduce hypocalcemia occurrence in dairy cows. But, for maximum success, it’s important your herd receives the optimal balance of minerals in its ration.

The key nutrients

The DCAD is calculated using nutrient levels of potassium, sodium, sulphur and chlorine. But there are also others worth paying close attention to. In every case, getting the quantity right is essential. For an effective DCAD strategy, farmers must also monitor common dietary minerals, including phosphorous and magnesium. The importance of maintaining the right balance can be seen in the figure below. Magnesium positively affects the hormonal regulation of the cow’s blood calcium levels, but is in turn negatively impacted by high potassium levels.



Phosphorous: why less is more

Another crucial micromineral, phosphorous, is thought to assist in processing calcium. However, it’s not always a case of the more the merrier. For example, a higher phosphorous intake can limit a cow’s calcium absorption, increasing the risk of hypocalcemia. This is because too much phosphorous can reduce the formation and increase the degradation of dihydroxyvitamin D – which is essential for calcium absorption in the intestine.


Because cows don’t require a lot of phosphorous during the dry period, you can cut the intake to 2-3 grams per kg of dry matter (DM). Creating a low-phosphorous diet for dry cows involves additional costs, but with clear long-term health and economic benefits, you’ll find this is money well spent. Indeed, studies show that cutting phosphorous by 1 gram per kg DM during close-up can result in up to 21% fewer cases of sub-clinical hypocalcemia (SCHC).


Milking the economic benefit

Striking the right nutritional balance can play a key role in improving your long-term herd health as well as your farm’s wider performance. 

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