Effects of Selenium Supplementation During Different Trimesters of Pregnancy on Total and Vibrio coralliilyticus Specific IgM Antibody Concentrations in Beef Cows at Parturition
Background: The immune response to microbial infections is compromised in beef cattle at parturition. Innate and adaptive immunoglobulin M (IgM) serve as initial antibodies during microbial infection before the generation of adaptive immunoglobulin G (IgG). Selenium (Se) is an essential micronutrient required by all mammals, which can improve immune responses in beef cattle.
Objective: To determine the best time during pregnancy to supplement beef cows with organic Se to optimize immune function at parturition. We hypothesized that feeding Se yeast to pregnant beef cows in each of the three trimesters of pregnancy would alter total and Vibrio coralliilyticus specific IgM concentrations in cows at parturition.
Animals: A total of 79 black Angus and Angus cross beef cows were used in the study. All of the cattle were housed and obtained routine care including deworming and vaccinations at Oregon State University Soap Creek Ranch, Corvallis OR.
Procedures Twenty-three cows were in the control group; they did not receive any Se-yeast boluses. Twenty-one cows were in Group 1. These cows received three 52.5g Se-Yeast boluses once weekly in the first 3 months of their pregnancy. Fifteen cows were in Group 2. These cows received three 52.5g Se-Yeast boluses once weekly in the second trimester of pregnancy from months three to six. Twenty cows were in Group 3. These cows received three 52.5g Se-Yeast boluses once weekly in the third trimester of pregnancy, from months six through nine. Thus, all cows except controls received 105 mg Se/week from the three boluses administered during their specific treatment trimester, equating to five times the upper limit for US FDA Se administration regulations. Blood was collected at parturition from all cows. A commercial ELISA kit was used to measure total IgM antibody concentrations in serum of beef cows at parturition (Bethyl Bovine IgM Kit). To test for Vibrio coralliilyticus specific IgM antibody concentrations and whether differences in concentration occur with timing of Se treatments during gestation, an ELISA protocol was also developed for detecting Vibrio coralliilyticus specific IgM antibodies.
Results: Total and Vibrio coralliilyticus specific IgM concentrations were highly correlated (r = 0.78; P < 0.0001). Compared with values of Control cows, cows treated with Se in the first, second, or third trimester of pregnancy, respectively, had similar serum total IgM concentrations (P = 0.43; P = 0.86, and P = 0.19, respectively) and similar Vibrio coralliilyticus specific IgM concentrations (P = 0.47; P = 0.55, and P = 0.67, respectively).
Conclusions and Clinical Relevance: These findings show that weekly organic Se-yeast supplementation using a 105 mg Se/wk dosage during different trimesters of pregnancy does not affect IgM concentrations in beef cows after parturition. We do not provide evidence for Se-yeast bolus Se supplementation of beef cows during pregnancy impacting IgM production at calving
