Real World Vitamin Recommendations

Ohio State University

Proper animal nutrition is backed up by sound knowledge of cattle vitamin requirements. Bill Weiss, Professor of Animal Sciences, Ohio State University reviews the current Nutrient Requirements of Dairy Cattle (NRC), concluding they are a useful nutrition guide.


The current Dairy NRC (2001) is largely based on data published before 2000. Although the book remains a valuable resource and much of its information is still relevant, few things remain constant.
During the past decade, we have increased our knowledge about dairy cattle nutrition. Most of the new knowledge represents incremental modifications rather than wholesale changes; however, some of these changes can have a significant economic impact. At times, applying the information contained in the NRC (even if nothing has changed) to specific farm situations is not straightforward, and the requirements presented in the NRC must be modified for a host of reasons.

One of the feed categories that needs to be examined in light of new research is vitamin supplementation. Vitamins add cost to the diet, but when supplemented appropriately, they will increase income over feed costs and improve cow health.

Vitamin A

Vitamin A is among the least stable vitamins, and loss of activity can be approximately 10% per month depending on storage conditions. In addition, potency can vary among sources of supplemental vitamin A. This uncertainty justifies a small safety factor (10% or 20% excess). One study reported that feeding vitamin A at about twice the NRC recommendation increased milk yield. Therefore, supplementing vitamin A at 1.1 to 2 times the NRC recommendation (e.g., 80,000 to 150,000 IU/day for Holstein cows) can be justified, but supplementation in excess of 150,000 IU/day is not supported by current data. Indeed, one study reported a significant decrease in milk yield when early lactation cows were supplemented with about 550,000 IU/day.

Vitamin D

The current recommendation for vitamin D is adequate with respect to calcium metabolism, but we now know that vitamin D has a multitude of functions in addition to calcium homeostasis. Studies with humans and limited research with bovine cells have shown that vitamin D has important roles in immune function and that blood concentrations of 25-hydroxy (OH) vitamin D (humans) required for maximal immune response was greater than concentrations required for optimal calcium metabolism.
Infusing 25-OH vitamin D into experimentally infected (E. coli) mammary glands reduced clinical signs of mastitis and reduced bacterial counts. Dairy cows housed inside without exposure to sun and fed vitamin D at NRC recommendations had significantly lower plasma concentrations of 25-OH vitamin D than cows fed no supplemental vitamin D but housed outside in the summer with extensive sun exposure.
We do not know the optimal concentration of plasma 25-OH vitamin D, but current supplementation rates do not provide for maximal concentrations. Much more research is needed on vitamin D, but circumstantial evidence suggests benefits from increasing supplementation up to 2 times the NRC recommendation or ~40,000 IU/day.

Vitamin E

No new data are available refuting current NRC requirements for vitamin E except during the prefresh period. Increasing vitamin E intake to 2,000 and 4,000 IU/day during the last 14 to 21 days of gestation (i.e., the prefresh group) can help reduce mastitis, retained fetal membranes, and perhaps metritis. New data suggest oversupplementation for the entire dry period (3,000 IU/day) may be a risk factor for mastitis and should be avoided.

Water-Soluble Vitamins

Supplementation of biotin, niacin, and choline are the only water-soluble vitamins that currently have much application to dairy nutrition (B12 can be an issue if adequate cobalt is not provided). The use of supplemental biotin at about 20 mg/day is clearly justified based on expected milk yield (approximately 2.9 lb/day increase) and improved hoof health.
These benefits usually have substantially more value than the cost of supplementation and the cost of the increased feed intake needed to support the higher milk yields. Rumen-protected (RP) choline (at approximately 50 g/day of RP product) increases milk yield (4.4 lb/day) in early lactation (most studies started supplementation in the prefresh diet and continued until about 60 days in milk).
The cost of supplementation is high (but so is the potential return), and this cost along with the cost of the increased feed intake that accompanies the increased milk yield has to be compared to the value of the increased milk output.
If early lactation cows are housed and fed with other cows (e.g., a one-group TMR), overall responses, and return on investment, may not be cost effective. Accumulating data show potential benefits of RP-choline in preventing ketosis and/or fatty liver. Although some individual studies show substantial milk yield responses to supplemental niacin (6 to 12 g/day), many experiments revealed no effect.
In a comprehensive summary of published data, no overall effect of supplementing 6 g/day was observed, but with 12 g/day, the expected milk response was 1.1 lb/day.
A summary of other studies determined that a positive response on milk production to supplemental niacin was likely during the first 100 days of lactation (many of these studies started supplementation in the dry period), but later lactation cows did not respond to niacin supplementation. At current prices, this often will not be a profitable response. Limiting supplementation (at 12 g/day) to cows less than 100 days in milk increases the likelihood of a positive and profitable response.

Table 1. Recommended Daily Rates of Vitamin Supplementation for Average Dairy Cows that are not Fed Fresh Forage.

1 NRC recommendations are given on a body weight (BW) basis. For this table, assumed body weights were 1,100 and 990 pounds for a dry and lactating Jersey and 1,580 and 1,430 pounds for a dry and lactating Holstein.

*Use depends on the price of milk and the cost of the supplement and feed (i.e., whether it will be profitable).


Current NRC recommendations for vitamins A and E appear adequate, except during the prefresh period when additional vitamin E can be beneficial. New information regarding vitamin D in dairy cows is desperately needed in light of research with humans and other animals. Circumstantial data suggest that doubling the current recommendation of vitamin D may have benefits. Supplemental biotin and RP-choline will increase milk yields; however, return on investment (considering the cost of the supplement, cost of increased feed intake, and value of the additional milk) must first be evaluated.

Author Information

Bill Weiss, Professor of Animal Sciences
The Ohio State University


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