Vitamins for Dairy Cows

Until recently there has not been a significant push to supplement B vitamins in dairy cow diets since they are known to be synthesized in large amounts in a cow's rumen.

It has been recognized for many years that B vitamins are essential for various aspects of a cow's metabolism, her overall health and milk production.

As milk production per cow has increased over the years, it may very well be that a cow's ability to synthesize enough B vitamins may be a limiting factor in milk production.

With the increased demand for greater levels of milk production from modern dairy herds, ruminant scientists and researchers are taking a closer look at some of the B vitamins as possibly being limiting for milk production and milk components as well as being a factor in preventing some metabolic diseases.

B vitamins are a group of vitamins that are water-soluble and necessary for maintenance, growth, milk production and reproduction. A partial list includes:
• Thiamine, which is involved in energy metabolism as well as the synthesis of nucleic acids and neurotransmitters.

• Riboflavin is found in the enzymes involved with energy transfer from carbohydrates, proteins and fats.

• Niacin is needed for the synthesis of glycerol, the oxidation of fatty acids and the synthesis of certain steroids and amino acids.

• Pantothenic acid is a required element of an important enzyme necessary for the conversion of all organic substances to energy.

• Biotin is a key element in the formation of keratin and epidermal cells necessary for the formation of hooves. In the rumen it is needed for the formation of propionate, one of the key VFAs.

• Folic acid is a key component for cell division, protein metabolism and the synthesis of red blood cells.

• Pyridoxine is converted into a compound that is a co-factor in the metabolism of proteins as well as the metabolism of carbohydrates.

• B12 is another necessary component of energy metabolism as well as the synthesis of the all-important and often-limiting amino acid, methionine.

Rumen microbes have the ability to both destroy and synthesize B vitamins. Research has shown that many B vitamins found coming from feedstuffs are largely destroyed in the rumen, but, ironically, the rumen microbes make those same B vitamins that are then metabolized in the small intestine.

Many of the B vitamins are instrumental for both energy and protein metabolism. It is believed that vitamins work together synergistically with minerals.

Several metabolic diseases in dairy cows such as milk fever, metritis, ketosis and fatty liver syndrome are associated with a marginal energy balance. Even though they are required only in very small amounts, vitamins are necessary for nutrient metabolism in all animals.

The National Research Council (NRC 2001) has determined that two specific B vitamins, folic acid and pantothenic acid, are likely to be nutritionally limiting. Even though deficiencies are rare, studies have shown that cows respond to judicious applications of B vitamins.

According to Dr. Essi Evans, it is difficult to design studies that limit B vitamin intakes since the rumen microbes go ahead and synthesize them. Her work focuses on providing B vitamins in a form that protects them from rumen destruction as a means of getting added levels into the small intestine.

A research trial supplementing dairy cows with ruminally protected B vitamins was conducted to see if a selection of vitamins would increase production of milk and milk components, in particular those B vitamins involved with milk protein synthesis.

The trials done on two different California herds used a rumen-protected B vitamin complex containing folic acid, pantothenic acid, biotin and pyridoxine.

That study concluded that both milk production and milk protein were improved, particularly in those cows milking in early lactation.

The study also concluded that: "... the results can be interpreted to suggest that the mechanism leading to the positive overall production response with B vitamin supplementation was due to improvements in metabolic efficiency of intermediary metabolism, rather than increased metabolic activity per se ... the general increase in lactational performance was probably due to increases in metabolic efficiencies in energy and protein metabolism, particularly in the early lactation cows."

The principle use of biotin for dairy cows has been to improve hoof health. However, hoof improvements will not be noticeable until the new growth is at the wear surface, which can be a considerable amount of time - 12 to 18 months later. Several studies have also shown that added biotin also increased milk production.

According to Dr. Evans, choline is often included as a B vitamin, but it differs from other vitamins, because animals need higher levels similar to micro-minerals.

In addition to facilitating metabolism, which is the definition of a vitamin, choline is also used in the growth of cells. Choline helps the movement of fat through liquid, such as blood.

Choline also helps to remove fat from the liver, which makes it particularly valuable in transition cow diets where fatty-liver syndrome may be suspected. Choline is rapidly destroyed in the rumen and also must be fed in a rumen-protected form in order to be available to the cow.

While there is much still to be learned regarding B vitamins and how they function in dairy cows, Dr. Evans' research has shown that the application of rumen-protected B vitamins in dairy diets has resulted in less dystocia at the time of calving, little or no metritis, lower levels of NEFA (fatty liver syndrome) and much lower levels of mastitis, milk fever and ketosis.

The reduction of these metabolic problems will assist dairy farmers in maintaining healthy and more productive herds. PD

This article was originally published in Progressive Dairyman Magazine in February 2011. Engormix.com thanks the author and the magazine for the contribution.