Livestock feed supplier Rumenco has said that beef and dairy producers that prioritise macro and micronutrients in the weeks leading up to calving will benefit in both the calving and post-calving period.

Nutritionist for the company, Dr. Alison Bond, said minerals like iodine, copper, selenium and magnesium are essential for normal physiological functioning and are required in increased amounts for optimal growth, immunity and fertility.

Bond said the pre-calving period can be considered to be the most critical in a cow’s production cycle, and highlighted the importance of the inclusion for the four nutrients in the diet.

“Nutrient requirements are high in the run-up to calving, with most herds requiring supplementation of essential macro and micronutrients,” she said.

Cows need the “key performance minerals” at good levels to optimise both cow and calf performance, she said.


Bond said magnesium is required for all metabolic pathways including muscle contraction, nerve signalling and bone formation.

Magnesium, she said, is the most important macromineral for pre-calving cows and heifers.

“Supplementation for both spring and autumn calvers is essential because of the low levels of magnesium in the grass during those times, while also supporting muscle contraction for the calving process,” she said.

Furthermore, Bond said, cattle do not store magnesium well in the body and therefore they need to be supplied with supplementation daily.


Selenium is transferred readily across the placenta and feeding good levels to the cow on the approach to calving will ensure the calf has good levels at birth, Bond said.

Selenium plays an important role in triggering the breakdown of brown adipose tissue in the newborn calf therefore supporting calf vigour, ensuring they stand and suckle quickly and helping to prevent hypothermia.

Through its role as an antioxidant, Bond said, selenium is important for the immune response helping to reduce inflammation and enhance immunity.

“Selenium and vitamin E work in conjunction as natural antioxidants, protecting tissues from oxidative stress and the breakdown of cell membranes,” she said.

“The antioxidant actions of selenium and vitamin E are important for the immune response, particularly white blood cell function, and therefore help to reduce inflammation and maintain disease resistance throughout the periparturient period.”


To synthesise thyroid hormones for control of energy metabolism and metabolic rate, pre-calving cows require iodine Bon said.

It is especially important for cattle consuming brassicas and legumes, she said. Compounds in these forages block utilisation of dietary iodine, requiring higher levels of supplementation.

“Regardless of diet, all pre-calving cattle require iodine supplementation since it is not stored in the body,” she said.

“Therefore, a continuous supply from the diet is required for the normal production of the thyroid hormones.”


“Especially in the final three weeks before calving, we see copper requirements increase significantly,” Bond said.

“This trace element is essential for multiple different enzyme systems in the body including those involved in energy metabolism, connective tissue development and antioxidant systems.”

Copper is also a major contributor to the development of uterine tissue, she said, with deficiency leading to a delay return to oestrus and reduce conception rates, subsequently extending the calving interval and reducing herd profitability.