The overlooked trace minerals in the modern dairy diet

Most dairy research tends to focus on protein and energy needs, and trace minerals are often overlooked. Yet when we fail to consider the role of trace minerals, problems can arise, including interferences or interactions with minerals in feed and water.

Roger Scaletti

Zinc (Zn) is essential to more than 200 enzyme systems at work in the animal, such as carbohydrate and energy metabolism, protein synthesis, nucleic acid metabolism, epithelial integrity, cell repair and division, and utilization of vitamins A and E.

It is needed for the development and function of the immune system and is critical to the cellular function of cells, including heterophils, basophils, macrophages and T-lymphocytes. Zinc is critical for reproduction because of its involvement in sexual maturity, reproductive capacity and semen quality. It is also essential for wound healing.
Copper (Cu) is an important component of immune system enzymes. It is necessary to increase structural health and elasticity of connective tissue and blood vessels as well as to increase strength of bone. Copper is also needed for the metabolism of iron and maturation of red blood cells.
Manganese (Mn) is a co-factor for enzymes in the metabolism of carbohydrates, fats, proteins and nucleic acids. It is essential for normal brain function and is important for proper immune function and wound healing. Manganese is involved in the formation of collagen, bone growth, urea formation, fatty acid synthesis, cholesterol synthesis and protein digestion.
Selenium (Se) is critical to proper enzyme function and cellular antioxidant systems. It is involved in muscle contraction and immune functions and is important for reproduction.

Form defines function

Understanding the difference between organic and inorganic minerals is important. When we look closely at organic minerals, or minerals with a carbon structure, we find they are in the same form we would see in corn, grain or forages. In other words, they are similar to the minerals stored in plants.

Organic forms of zinc, manganese, copper and cobalt – included in the Association of American Feed Control Officials (AAFCO) category proteinate – are produced by replicating plant material in a patented manufacturing process, which chelates the minerals onto amino acids and peptides.

Organic selenium that is in the AAFCO category selenium yeast is derived from yeast incorporating selenium salts into cellular organic material.

Why not just supplement with more inorganics?

Due to their lower biological activity, various issues can arise when using inorganic minerals, including associated environmental concerns. Research studies have demonstrated over-fortification of trace minerals can elevate antibiotic resistance in swine operations, as bacteria like salmonella develop tolerance to high levels of copper and zinc.

Inorganic minerals can have various mineral and vitamin interactions, and they can serve as antagonists, interfering with normal biological processes.

Total replacement: Supplementing only organic trace minerals

Peer-reviewed research has demonstrated advantages to dairy cows when only supplementing with organic trace minerals. Research in 2007 showed greater milk production (P less than 0.05) over the first two months of lactation when using only proteinate forms of minerals as a total replacement to supply 600 milligrams of zinc, 400 milligrams of manganese and 120 milligrams of copper – compared to cows supplemented with inorganic mineral sources or cows supplemented with half of the trace minerals from mineral proteinates and half from inorganic sources.

Additionally, the total replacement cows produced more milk (P less than 0.05) over the first 100 days of lactation than cows supplemented with inorganic minerals. Somatic cell count was also lower (P less than 0.05) in cows supplemented with organic minerals compared to cows supplemented with inorganic minerals.

A study in 2009 showed increased milk production (P less than 0.05) when organic zinc was supplemented at 600 milligrams per cow per day, compared to the same amount of zinc from an inorganic source.

Research conducted in 2012 showed decreased bacteria count in milk (P less than 0.05) and increased milk production (P less than 0.05) in response to an intramammary challenge with E. coli in one quarter of each cow when cows were supplemented with copper proteinate at 200 mg per cow per day, compared to the same amount of copper from copper sulfate.

More recent research has combined multiple organic minerals, such as zinc, manganese, copper, cobalt and selenium, to evaluate more complete trace mineral nutrition programs. Researchers in 2016 compared total replacement with organic minerals to diets supplemented with inorganic sources.

The total replacement diets, with some minerals fed at lower levels compared to the inorganic mineral treatment, resulted in greater total volatile fatty acid production (P equal to 0.08) and greater total butyrate production (P less than 0.05).

These differences could be explained by the higher bioavailability of the organic mineral treatment and accelerated replication of the rumen micro-organisms.

This research also confirms there is not a rumen requirement for inorganic minerals, as the organic mineral treatment contained no inorganic minerals yet improved rumen function, as was measured by increased total volatile fatty acid production and increased butyrate production.

In a study conducted in 2016, researchers supplemented either organic trace minerals or trace minerals as sulfates/selenite to dry cows and continued these treatments to calves after they were born.

Providing the organic mineral program to pregnant cows or their calves improved overall health of the calves, as measured by general health scores (P less than 0.05) – while plasma haptoglobin, an acute phase protein produced by the liver during inflammation, was only reduced (P less than 0.01) in calves when organic minerals were supplemented to the dry cows.

A study in 2018 maintained heifer calves from another study on either organic or inorganic supplementation during the heifer development period and into their first lactation. Cows supplemented with organic trace minerals gave birth to daughters that calved 26.5 days earlier (P equal to 0.05) than inorganic supplemented cows. Presumably, this is explained by fetal programing due to nutrition.

Heifers fed organic trace minerals tended to calve 22 days earlier (P less than 0.07) than those supplemented with sulfates/selenite. Additionally, average milk yield in early lactation was greater (P less than 0.05) in heifers supplemented with organic trace minerals.

The adage that “form defines function,” especially when it comes to minerals, is both important and true. Research across the world continues to prove the impact of organic minerals on herd health and performance.