Selenium yeast for dairy calf feeds

Our objective was to test the hypothesis that Se yeast (SY) would improve performance and health of calves. Holstein bull calves (48 in Experiment 1 and 48 in Experiment 2), initially less than 1 week old, were used in 2 × 2 factorial experiments with sodium selenite or selenium yeast as factors in both experiments. In Experiment 1, fatty acid composition was the second factor, while in Experiment 2 it was the milk replacer (MR) program. In Experiment 1, calves were fed 0.45 kg of a MR (200 g crude protein (CP), 200 g fat/kg) daily for 42 d and weaned. In Experiment 2, half the calves were fed 0.45 kg of a MR powder (200 g CP, 200 g fat/kg) daily for 42 d, and the other half received a MR (260 g CP, 170 g fat/kg) at 0.68 kg daily (as-fed basis). Starter feeds were fed to promote ad libitum intake and contained mainly corn grain and soybean meal, were 180 g CP/kg as-fed. Calves were housed in individual pens for 56 d. No differences in performance or health between Se sources occured in either experiment. Whole blood Se levels did not differ between treatments in Experiment 1 and appeared adequate compared to levels reported in the literature, but there was a significant decline (P<0.05) of whole blood Se levels over time. In these experiments, Se source (i.e., sodium selenite or selenium yeast) in the diet did not impact body weight gain, intake, feed efficiency or health.