“Vitamins are not that difficult compared to everything else you have to do to get a good diet, but they still deserve some thought,” said Bill Weiss during the July Hoard’s Dairyman webinar.

The professor emeritus from The Ohio State University explained that nutritionists must get other components of the ration, such as energy, carbohydrates, and minerals, correct first. Then, the focus can shift to vitamins, and the main decision is how much to include.

“Vitamins are great and wonderful, and they are essential, but too much can cause problems,” he shared, adding that some vitamins on a mass basis can be toxic. Because they don’t weigh much, there is a fine balance between too little of a vitamin and too much.

When fed in the right amount, Weiss noted that herds can see improved cow health, better reproduction, and greater milk yield, due in part to cow health but also because of metabolic reasons. Vitamins can also elevate the nutritional value of milk, which unfortunately doesn’t garner farmers a higher milk price but does make milk an excellent source of nutrients.

“The proper amount of vitamins is a very profitable addition to diets,” Weiss noted.

However, too much of certain vitamins can be detrimental to cow health and can also lower milk production. In addition, since vitamins are not free, Weiss said feeding too much can inflate feed costs and reduce overall profitability.

Just about anything a cow does needs a vitamin, Weiss shared. From acting as enzyme cofactors to regulating genes, vitamins are needed in many ways, and responses to vitamin deficiencies or excess are wide-ranging.

The vitamins that are essential depend on the species; for instance, some vitamins needed by humans are not needed by cows. Weiss said we believe there are 12 vitamins that cows must absorb:

• Fat soluble vitamins of A, D, E, and K
• Water soluble vitamins of biotin, B-12, folic acid, niacin, pantothenic acid, pyridoxine, riboflavin, and thiamine

He also noted that even though choline does not fit the classical definition of a vitamin, it is often considered to be the 13th vitamin needed by cows since it doesn’t easily fit into another category.

To learn about some of these vitamins in more detail, watch the July Hoard’s Dairyman webinar, titled “Vitamins for dairy cattle.”