Proper nutrition plays an obvious and substantial role in helping cows through the transition period and ensuring a good start in the following lactation. At the core of successful transition is the impact of nutrition on the cow’s immune function, which is the basis for her ability to stave off infections, metabolic disorders and other challenges that threaten health and performance.

For instance, vitamin D and calcium levels have significant impacts on the functionality of immune cells. Other dietary components like vitamin E and selenium, and trace minerals such as copper and zinc, may also influence immune function.

Increased health disorders have been associated with alterations in bovine immune mechanisms. Many different aspects of the bovine immune system change during the transition period, but uncontrolled inflammation is a dominant factor in several economically important disorders such as metritis and mastitis.

While the specific biological mechanism may not be completely understood, it is obvious from research literature and on-farm experiences that cows with compromised immune function are subject to many different “breakdowns,” whether it is a specific disease, reduced reproductive performance or lower milk production.

As a result, researchers and dairy advisers need to begin to think about nutrition and immunity not as exclusive concepts but rather as integrated systems whereby the activity or events in one system have direct effects on the other. Fortunately, researchers and nutritionists are learning more every day about the impact specific nutritional components play on immune function.


One key opportunity to improve immune function is through essential fatty acids (EFAs). EFAs are essential for cow health and productivity; they cannot be synthesized by the animal and must be provided by the diet.

Dairy cows are the beneficiaries of this increased understanding of EFAs. This knowledge is quickly leading to increased gains in transition performance and overall profitability as rations are formulated to include EFAs in explicit combination.

Omega-3 and Omega-6 EFAs

The key ( Table 1 ) lies in the EFAs chosen. EFAs, specifically Omega-3 (18:3 linolenic) and Omega-6 (18:2 linoleic), serve key functions related to dairy cows’ reproductive health and performance, including:

  • Supporting the production of specific reproductive hormones, especially progesterone, which influences pregnancy maintenance
  • Aiding in prostaglandin production, which causes ovulation and a subsequent estrous cycle; in addition, they enhance visible signs of estrus and increase blood flow to the ovaries to promote follicle growth

essential fatty acid role “In our studies, we’ve found that manipulating Omega-3 and Omega-6 in the diet influenced lactation performance and fertility,” says Dr. Jose Santos, University of Florida professor of animal science.

“The inclusion of Omega-3 and Omega-6 resulted in greater yields of milk and milk components and improved pregnancy per A.I. The benefits to fertility were observed primarily because of reduced pregnancy loss in the first 60 days of gestation.”

However, achieving these benefits can be challenging as cows may not consume enough EFAs through commodity feed sources typically included in the diet. While several feeds, like cottonseeds and whole soybeans, contain certain levels of EFAs, they are often altered in the rumen through biohydrogenation, making them unavailable as EFAs and useless to meet daily nutrition requirements.

That’s where scientifically proven feed ingredients that contain both the Omega-3 and Omega-6 EFAs that are protected so they are not biohydrogenated and rendered unavailable are helpful. These EFAs can help dairies achieve their desired outcomes of improved immune function and optimized cow health and performance.

Repeated on-farm results

Five recent on-farm nutrition trials from across the U.S. demonstrate the wide-ranging opportunities producers have to positively influence cow health and productivity through the targeted addition of Omega-3 and Omega-6 EFAs to the ration.

The results, shown in Figure 2 , indicate the positive health impacts obtained from overall improved immune function.

essential fatty acid scores

Click here or on the image above to open it at full size in a new window. (PDF, 620KB)

Interestingly, each farm represents a different management philosophy, grouping strategy, base ration, standard operation procedures, geography and climatic influence, suggesting that no single way of dairying is required for successful adaptation.

The dairies fed the EFAs at the same rate (0.25 pounds per head per day) for the same amount of time prepartum (21 days), but the time and amount fed postpartum varied across operations.

Time and again, these on-farm trials show that adding both Omega-3 and Omega-6 EFAs to the transition diet pre- and postpartum improves parameters like:

  • Lowered blood beta-hydroxybutyrate (BHBA) levels, resulting in lower incidence of metabolic disorders
  • Lowered first linear somatic cell score for each herd
  • Reduced embryonic death
  • Increased pregnancy and conception rates
  • Improved first milk weights for dairies that tracked this parameter

More detail

It’s important to note several specific results from these trials. For example:

  • In the herd that measured blood BHBA levels, the dietary change lowered this measure by 44 percent. On a herd level, BHBA is a useful indicator of the ability of cows to deal with metabolic challenges in the transition period.

    At the individual cow level, increased serum concentrations of BHBA around calving have been associated with lower milk production and impaired early reproduction.

  • Each dairy showed lowered early embryonic deaths, often cutting this incidence in half or more.
  • Each dairy also showed significant gains in pregnancy rates. Results ranged from 7 to 9 percent increases in this parameter.
  • Lastly, directly correlated to increased pregnancy rates, herd conception rates also rose from 7 to 15 percent.

While the individual results are significant, it’s also important to note when reading the chart that these desirable decreases and increases are consistent across farms in direction. (If a parameter went down, it did so across all herds; likewise, a parameter that increased did so across all herds.)

Keep in mind, as well, that despite incomplete milk production data for some farms, net profit per cow increased across the board when EFAs were included in the diet. This indicates the investment in the EFAs was well-founded. And the results lend further credence to the premise that healthier cows are more productive cows in virtually every measurable facet.

Therefore, as you seek increased health, performance and profitability outcomes on your operation, make sure your nutrition program provides a firm foundation to help you and your herd achieve these goals. PD

Joel Pankowski