Selenium Content of Plants Grown in Excreta from Selenium-Supplemented and Unsupplemented Cattle

Abstract

ABSTRACT Selenium concentration, plant yield, and total Se content of three plant species subject to two rates of manure from Se-supplemented (S) and unsupplemented control (C) cattle were compared. The S cattle were supplemented with two rumen-retained boluses of 90% iron and 10% elemental Se. Mean whole blood Se ofC cattle was 69 ppb (SD 29) and S cattle was 120 ppb (SD 169); pooled slurries of 70% feces:30% urine by weight were 70 ppb Se for C and 77 ppb for S cattle. Manure slurries from C and S cattle were applied at rates of 5.6 or 22.4 kg/ha to either Fawn Tall Fescue, barley, or black mustard in plastic pots for growth in a greenhouse. A positive control (Sp) was established by spiking the C manure slurry with 22.3 mg sodium selenite/pot at the 5.6 kg/ha application rate. Yield of above-ground plant material increased with manure application (P=.0001). The Se concentration decreased (P=.008) with greater applications of manure, apparently a dilution effect due to increased plant growth. Excreta from S cattle compared to excreta from C cattle resulted in a plant species × manure source interaction for Se concentration (P=.04) and total Se content (P=.04). These interactions may have occurred due to differences in plant phenology. When averaged over all species, excreta from S cattle compared to C cattle did not result in significantly different yield (C = 15.3, S = 14.6 g/pot, SEM = .64), Se concentration (C = 262, S = 296 ppb, SEM = 36), or total Se content (C = 3.82, S = 4.36 μg/pot, SEM = .64).