Header for print stylesheet
You are here:    

Vitamin E and incoming beef calves

The beef industry continues to fine-tune receiving programs to prevent the poor performance and disease outbreaks that are a continual risk with incoming cattle at the feedlot. Shipping fever has always been a central concern, of course, but it becomes even more urgent as the industry expands its understanding of the effects. Field experience now suggests that on top of the direct costs of treatment, there are continued indirect costs in poor performance as "cured" animals lag their pen mates through finishing.

Today's preventive programs are naturally multifaceted--just as the root causes of shipping fever are a confluence of stress and pathogens such as Pasteurella haemolytica and P. multocida. Practices include creep feeding, early introduction to the feedbunk, more thorough vaccination, longer intervals between stressful procedures, and sound nutrition.

Vitamin E has long been recognized as a component of sound nutrition important to maintain immunocompetence. Vitamin E supplementation in starter rations makes sense, given basic research into the biochemistry of infection and stress in cattle and other species as well. Studies have shown that vitamin E requirements increase in the presence of stress, while others have reported enhanced humoral and cell-mediated immune responses with vitamin E supplementation.

A recent study by Kansas State University researchers (Corah et al., 1996) extended the use of vitamin E supplementation to preconditioning instead of waiting until the animals were under stress and exposed to new pathogens at the feedlot. Calves in the treatment group received 500 IU of vitamin E and 0.3 ppm of selenium per head daily for the last 47 days before weaning. The researchers reported that average daily gains were 13 percent greater than for unsupplemented controls during the following 28 days of the study, which included transportation and a standard commercial receiving program.

The differences in performance with supplementation occurred even though the calves faced less disease pressure than many cattle arriving at a feedlot. Shipping was limited to an overnight haul of 132 miles; the calves had been well managed; they had not been commingled at a sale barn; and they did not face a severe infectious insult on arrival or before.

Previous research tended to concentrate on vitamin E supplementation under more severe conditions. In a weighted analysis of studies to date, Secrist  et al. (1995) reported that the value of supplementation appeared to be greater when the animals were under stress (Figure 1).

 
Figure 1

For example, Lee et al. (1985) included 400 IU of vitamin E per head daily in rations fed to steers hauled 22 hours from Kentucky to western Kansas. The researchers reported a 6 percent increase in average daily gain, a 15 percent improvement in feed efficiency and a 10 percent reduction in morbidity in supplemented steers compared to unsupplemented controls (Figure 2).

 
Figure 2

Gill et al. (1986) reported similar results in a 28-day study with 500-lb long-haul calves purchased at auction barns. Supplemented calves received 1,600 IU per head daily for the first 21 days and 800 IU per head daily for the next seven days. Compared to unsupplemented controls, the supplemented calves led in every category, with 22 percent higher gain, 25 percent lower feed to gain ratio and 13 percent and 11 percent reductions in morbidity and death loss, respectively.

In another Oklahoma study (Hays et al., 1987), cattle that were supplemented with 700 IU of vitamin E per head daily showed a 38 percent increase in average daily gain, a 26 percent enhancement in feed efficiency and a 21 percent decrease in sickness compared to unsupplemented controls.

Researchers have suggested several reasons for the differences in health and performance between supplemented animals and unsupplemented controls. In particular, they have linked vitamin E levels to the regulation of free radicals and similar destructive chemicals--though the relationship varies with immunocompetence and stress response.

A normal by-product of metabolism, these destructive chemicals are also an integral part of the immune response produced by neutrophils and other white blood cells to destroy the invading pathogens. Recent work with dairy cows found that as blood levels of vitamin E increased, so did the strength of the immune response to infection when measured by the ability of neutrophils to produce one form of radical oxygen species. The researchers reported that the speed of the neutrophil response to infection also increased with greater plasma levels of vitamin E. (See the accompanying article on mastitis.)

Yet these destructive chemicals present a two-edged sword. For example, neutrophils produce hydrogen peroxide to destroy pathogens, but accumulation within the neutrophils themselves is associated with reduced killing ability. Furthermore, free radicals can attack the body's own cells and cause oxidative damage if left unchecked. The antioxidant properties of vitamin E, which is an integral part of all lipid cellular membranes, serve to protect the cells from this damage by quenching free radicals.

Stress itself increases the production of free radicals, hence the need for the quenching ability of vitamin E, as the stress causes changes in the animal's metabolism. Stress also increases epinephrine and adrenocorticotrophic hormone levels, which in turn reduce the vitamin E concentrations in plasma, red blood cells and neutrophils. Sconberg et al. (1993) reported that these trends were all reversed when calves received supplemental dietary vitamin E at the rate of 1,000 IU per head daily.

Despite such promising work, vitamin E requirements for cattle are still not clearly established. The National Research Council gives a range of 15 to 60 IU per kilogram of diet (dry matter), which can work out to anywhere from 150 to 600 IU per head daily for growing and finishing cattle. According to Secrist et al. (1995), in the research studies to date, the supplemental vitamin E levels administered and the response of animals have varied widely, as have the animals' health history, prior vitamin E status and exposure to stress and pathogens. Feedlot operators working in tandem with their nutritionists should use dietary supplemental levels with a margin of safety that offsets these variations to help permit optimum health and performance.

 

References:

  • Corah, L.R., et al., 1996. Effects of preweaning vitamin E, selenium and copper supplementation on the performance, acute phase protein concentration and lymphocyte responsiveness of stressed beef calves. Kansas State University (Report).
  • Gill, D.R., et al., 1986. The effect of vitamin E supplementation on health and performance of newly arrived stocker cattle. Okla. State Univ. Anim. Sci. Res. Rep., p. 240.
  • Hays, V.S., et al., 1987. The effect of vitamin E supplementation on newly received stocker cattle. Okla. State Univ. Anim. Sci. Res. Rep., p. 198.
  • Lee, R.W., et al., 1985. Effect of vitamin supplementation on the performance of stressed beef calves. J. Anim. Sci. 61 (Suppl. 1):425.
  • Sconberg, S., et al., 1993. Effects of shipping, handling, adrenocorticotrophic hormone, and epinephrine on alpha-tocopherol content of bovine blood. Am. J. Vet. Res. 55(8):1287.
  • Secrist, D.S., et al., 1995. Effects of vitamin E on performance of feedlot cattle: a review. Oklahoma State University (Report).

 
footer for print stylesheet