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Effect of inorganic or organic selenium supplementation during gestation and lactation on feedlot performance of steer progeny
Angus x Simmental cows (n = 48, BW = 594 kg, BCS = 5.26, Age = 2.7), pregnant with male fetuses, were used to determine the effect selenium (Se) source during the last 80 d of gestation and first 105 d of lactation on progeny feedlot performance. At 203 d in gestation, cows were allotted to 1 of 3 treatments based on body weight, breed composition, and calf sire: no Se, inorganic Se, or organic Se. Diets were formulated to contain 10.4% CP and 0.90 Mcal/kg NEg during gestation and 12.1% CP and 1.01 Mcal/kg NEg during lactation. Basal diets contained 0.07 and 0.11 mg/kg Se for gestation and lactation diets; respectively. Diets were fed daily as a total mixed ration and Se was provided in a top-dress containing 0, 0.30 mg/kg Se as sodium selenite, or 0.30 mg/kg Se as Sel-Plex®. Treatment diets were fed through 105 d post-partum (DPP). At 105 DPP cow-calf pairs were commingled until weaning at 210 DPP. At 28 d post-weaning, steers (n = 47, BW = 301 kg) were placed in individual pens and fed a diet formulated to provide 13.9% CP, 1.24 Mcal/kg NEg, and 0.10 mg/kg Se. The diet was delivered as total mixed ration once daily. Steers from cows supplemented with organic Se entered the feedlot heavier (P= 0.02) and tended to be heavier on d 87 (P = 0.08) compared to steers from cows supplemented with inorganic Se. There was no difference in ADG among treatments (P ≥ 0.76), but steers from organic Se cows tended to spend fewer days on feed compared to steers from inorganic Se cows (P = 0.09). Steers from organic Se cows had a greater overall DMI compared to steers from inorganic Se cows (P = 0.04), but there was no difference in overall gain:feed ratio (P = 0.82). Dressing percentage was greater for steers from cows fed no Se compared with steers from cows fed either inorganic or organic Se (P = 0.03). Maternal Se source had no effect on hot carcass weight, back fat, %KPH, L. dorsi area, yield grade, marbling score, or quality grade distribution (P ≥ .17) of progeny. In conclusion, maternal supplementation with organic Se appears to have a long-term benefit on intake of steer progeny and may result in improvements in growth that decreases days in the feedlot.
Keywords: Selenium, Steer, Feedlot