title: Effects of feeding selenium-enriched alfalfa hay on immunity and health of weaned beef calves.
abstract: Previously, we reported that feeding selenium (Se)-enriched forage improves antibody titers in mature beef cows, and whole-blood Se concentrations and growth rates in weaned beef calves. Our current objective was to test whether beef calves fed Se-enriched alfalfa hay during the transition period between weaning and movement to a feedlot also have improved immune responses and slaughter weights. Recently weaned beef calves (n = 60) were fed an alfalfa-hay-based diet for 7 weeks, which was harvested from fields fertilized with sodium selenate at 0, 22.5, 45.0, or 89.9 g Se/ha. All calves were immunized with J-5 Escherichia coli bacterin. Serum was collected for antibody titers 2 weeks after the third immunization. Whole-blood neutrophils collected at 6 or 7 weeks were evaluated for total antioxidant potential, bacterial killing activity, and expression of genes associated with selenoproteins and innate immunity. Calves fed the highest versus the lowest level of Se-enriched alfalfa hay had higher antibody titers (P = 0.02), thioredoxin reductase-2 mRNA levels (P = 0.07), and a greater neutrophil total antioxidant potential (P = 0.10), whereas mRNA levels of interleukin-8 receptor (P = 0.02), L-selectin (P = 0.07), and thioredoxin reductase-1 (P = 0.07) were lower. In the feedlot, calves previously fed the highest-Se forage had lower mortality (P = 0.04) and greater slaughter weights (P = 0.02). Our results suggest that, in areas with low-forage Se concentrations, feeding beef calves Se-enriched alfalfa hay during the weaning transition period improves vaccination responses and subsequent growth and survival in the feedlot.
authors.affiliation: Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR, 97331-4802, USA, Jean.Hall@oregonstate.edu.
authors.forename: Jean A
authors.initials: JA
authors.lastname: Hall
authors.forename: Gerd
authors.initials: G
authors.lastname: Bobe
authors.forename: William R
authors.initials: WR
authors.lastname: Vorachek
authors.lastname: Hugejiletu
authors.forename: M Elena
authors.initials: ME
authors.lastname: Gorman
authors.forename: Wayne D
authors.initials: WD
authors.lastname: Mosher
authors.forename: Gene J
authors.initials: GJ
authors.lastname: Pirelli
mesh_terms: D000821:Animal Feed; D000818:Animals; D000975:Antioxidants; D004926:Escherichia coli / Q000276:immunology; D022361:Escherichia coli Vaccines / Q000276:immunology / Q000494:pharmacology; D005260:Female; D007113:Immunity, Innate / Q000187:drug effects*; D008297:Male; D009504:Neutrophils / Q000276:immunology*; D012643:Selenium / Q000494:pharmacology*; D051140:Selenoproteins / Q000276:immunology*
chemical_list: D000975:Antioxidants; D022361:Escherichia coli Vaccines; D051140:Selenoproteins; D012643:Selenium