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Fatty acids – a calf’s next line of (immune) defense

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Author: Tana Dennis, Ph.D., Calf and Heifer Specialist at

Future production success begins as early as the first day of a calf’s life. This is especially true when looking at the functionality of a calf’s immune system.

When calves are born, their immune system is not fully developed and is dependent upon colostrum antibodies to develop immune function. The most recent USDA NAHMS survey has shown the leading causes of calf loss are due to gastrointestinal and respiratory diseases. More than one-third of calves experienced one of several preventable diseases, even though the majority of large dairy operations indicated that calves received colostrum or were vaccinated for common calf-hood diseases (USDA, 2015).

At birth, calves are deficient in linolenic acid, an essential fatty acid that does not cross the placenta during gestation. Calves are dependent upon essential fatty acids being included in their diet from birth, as they cannot synthesize them naturally and likely have marginal stores at birth.

In five separate studies conducted at the Nurture Research Center (NRC), researchers found positive immune responses in calves fed a blend of short chain fatty acids, medium chain fatty acids, and linolenic acid in various milk replacer formulas. These positive responses included altered immune markers and reduction in scouring and incidences of Clostridial disease as compared to calves fed milk replacers without functional fatty acids (Table 1).

In Trials 1 and 2, researchers saw a decrease in tumor necrosis factor-alpha and urea nitrogen in blood, both of which are commonly known to increase after a pathogen challenge. Tumor necrosis factor-alpha is an inflammatory signal from the immune system associated with the fever response seen with infections or after vaccination. Lower concentrations of urea nitrogen in the blood indicates less nitrogen loss from fighting a pathogen challenge. Trials 1 and 2 also showed an increase in interleukin-4, which is associated with recruiting various globulin proteins to attack pathogens. Higher concentrations of globulin protein in the blood indicates stimulated antibody production. Together, these responses indicate enhanced immune function when functional fatty acids are fed to calves from birth.

Trials 3, 4, and 5 looked specifically at bovine viral diarrhea (BVD) and parainfluenza-3 (PI3) titers related to vaccinations. Each trial saw an increase in BVD and PI3 titers one month after booster vaccinations in calves fed the blend of functional fatty acids in milk replacer compared to control groups. Higher titers one month after a booster indicates longer term protection from disease. Calves fed the blend of functional fatty acids in Trials 4 and 5 also saw a decrease in Rotavirus- and Cryptosporidia-associated scouring and lower fever responses after vaccinating for Pasteurella (Figure 1).

Apart from modulating immunity, researchers have also seen additional benefits of functional fatty acids in calf diets including increased growth rates, performance, and diet digestibility. In a separate 56-day trial, researchers found average dairy gain (ADG), starter intake, feed efficiency, hip width change, and diet digestibility was greater for calves fed a blend of functional fatty acids compared to calves not fed functional fatty acids (Table 2). Similar responses in growth and health have also been observed when whole milk is supplemented with functional fatty acids (Table 3).

Focusing on using nutrition to support the immune system can build healthier calves, with additional lasting benefits. Do not let your calves go without the added protection provided by functional fatty acids. While most calf feeding programs focus on providing the right amount of protein and energy, these factors alone are not enough to enhance immune markers. Work with a nutritionist to formulate a diet that has the essential nutrients needed for growth, as well as immune support.

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