Influence of form of Se supplementation and tall fescue endophyte toxicity on the kidney transcriptome of grazing beef steers. Influence of form of Se supplementation and tall fescue endophyte toxicity on the kidney transcriptome of grazing beef steers

To test the hypothesis that average daily gain (ADG) and clinical parameters of steers grazing novel non-toxic (NTE) or toxic KY-31 (TE) endophyte-infected tall fescue would be improved by ad libitum intake of vitamin-mineral mixes (V-M) that contain 27 ppm Se as a 1:1 blend of SELPLEX:sodium selenite (MIX) vs. sodium selenite (ISe), 32 fescue-naïve beef steers depleted of Se were randomly assigned to ad libitum consumption ISe vs MIX for 35 d and fed enough of a NTE/alfalfa/grain diet to achieve 0.57 kg BW gain/d. Within Se-form treatments, 2 steers were randomly assigned to each of 4 NTE (ISe = 316 ± 31 kg, MIX = 315 ± 22 kg) or TE (ISe = 316 ± 37 kg, MIX = 314 ± 39 kg) paddocks for 84 d and had ad libitum access to their respective V-M. Steers were slaughtered over a 23-d period from day 90 to day 113 (August 27, 2019 to September 19, 2019) of the study and the left kidney removed. Overall design: A completely randomized design with a 2 × 2 factorial arrangement of treatments. 32 total samples were analyzed (n=8 for ISeTE, n=8 for ISeNTE, n=8 for MIXTE, and n=8 for MIXNTE ).