Submitted to: Small Ruminant Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/24/2012
Publication Date: 11/26/2012
Publication URL: http://handle.nal.usda.gov/10113/56723
Citation: Anugu, S., Petersson-Wolfe, C.S., Combs, G.F., Petersson, K.H. 2012. Effect of vitamin E on the immune system of ewes during late pregnancy and lactation. Small Ruminant Research. 111:83-89. Interpretive Summary: An experiment was conducted to whether a regimen of repeated, intramuscular injections of vitamin E improved immunity in pregnant and lactating ewes. Pregnant ewes were vitamin E or a placebo by bi-weekly injections starting 7 wks prior to the first ewe lambing and continuing lambs were weaned at 10-14 wks of age. All ewes were given booster vaccinations for Clostridium tetanus and C. perfringens at the beginning of the study. Results showed that vitamin E increased the production of immunoglobulin G by ewes in response to vaccination, and reduced the extent, magnitude and persistence of the drop in IgG production typically seen during the transition period. Vitamin E supplementation had unremarkable effects on circulating levels of selenium and the selenoenzyme glutathione peroxidase, but increased the vitamin E content of colostrums. These results point to vitamin E having utility in blunting the immune suppression that occurs during the transition period.
Technical Abstract: The present experiment was designed to determine the effects of a regimen of repeated, intramuscular (i.m.) injections of vitamin E (VE) on innate and humoral components of the immune response of pregnant and lactating ewes. Pregnant ewes were randomly assigned to two treatments consisting of i.m. injections of either VE (30 IU d-a-tocopherol/kg BW, n=10) or equivalent volume of a placebo (emulsified base, n=8). Injections were administered every two weeks starting 7 wks prior to the first ewe lambing and continuing for a total of 24 wks until weaning of lambs at 10-14 wks of age. All ewes were given a booster vaccination for Clostridium tetanus and Clostridium perfringens (C+D) at the beginning of the study. Blood and colostrum were analyzed for a-tocopherol and selenium (Se) content, and extracellular glutathione peroxidase (GPX3) activity as measures of antioxidant status; lysozyme activity as a measure of innate immunity and immunoglobulin G (IgG), and anti-tetanus toxoid IgG (IgG-T) concentration as a measure of humoral immune status. Results showed a significant treatment x week effect of VE supplementation on IgG production. VE supplementation increased IgG concentrations in ewes after their yearly booster vaccination against Clostridium tetanus and Clostridium perfringens; placebo-treated ewes showed no such response. The extent, magnitude and persistence of the decreased IgG production during the transition period were less in VE-supplemented ewes than controls. There was no effect of VE supplementation on production of IgG-T after vaccination. VE-supplementation of pregnant ewes had no effect on serum lysozyme activity. GPX3 increased in both treatment groups, peaking during the transition period. The a-tocopherol content of the colostrum of VE- supplemented ewes was greater than that of controls. In conclusion, VE supplementation of pregnant and lactating ewes had an equivocal effect on parameters used to assess immune function. The benefit of VE supplementation to pregnant and lactating ewes requires further research; however it may have utility in blunting the immune suppression that occurs during the transition period.