Effects of Supplemental Yeast Fermentation Product on Performance of Early-Weaned Calves on Pasture and Measures of Stress and Performance during a Feedlot Receiving Period1

The objective of this study was to investigate the effectiveness of a supplemental yeast fermentation product (YFP) on performance of early-weaned calves. Twenty-four calves were early weaned (66 ± 11 d of age) and randomly allocated to 8 ryegrass (Lolium multiflorum) pastures (January to May) and then moved onto 8 stargrass (Cynodon spp.) pastures (May to August). All calves received concentrate supplement (14 and 75% CP and TDN, respectively) at a rate of 1.0% BW daily. Two treatments were randomly allocated to calf groups consisting of a dried YFP (28 g/d of Diamond V XP per calf; Diamond V, Cedar Rapids, IA), or an isonitrogenous corn and cottonseed meal mixture (control). Average herbage mass, in vitro OM digestibility and CP, and calf ADG did not differ among treatments during ryegrass and stargrass grazing. Upon the conclusion of grazing, half of the calves within each treatment were loaded onto a livestock trailer and transported for a period of 24 h. Upon return, calves were allocated within supplement and transportation treatment into 12 individual drylot pens (2 calves per pen), and feed DMI and calf ADG were determined for 30 d. Plasma concentrations of the acute phase proteins ceruloplasmin and haptoglobin were determined on d 0, 1, 5, 9, 16, and 23 after transportation. Transportation and dietary treatment did not affect DMI, ADG, and plasma concentrations of haptoglobin or ceruloplasmin. The results of this study suggest that supplemental YFP may not be effective for enhancing early-weaned calf performance while on pasture or upon entry into the feedlot.