© 2019 A completely randomized design study with two feeding periods was used to evaluate the effects of substituting hammermilled Juniperus spp. for chopped alfalfa in growing steer diets. Steers (n = 44; initial body weight, BW = 343 kg) were fed in a Calan gate system (4 feeders/pen; 11 pens) for 112 days. During Period 1 (days 0 to 69), steers were fed 70% concentrate diets that only differed in roughage composition (juniper replaced 0, 33, 66 or 100% of the alfalfa portion; 0JUN, 33JUN, 66JUN, or 100JUN, respectively). In Period 2 (days 70 to 112), steers were transitioned to a common 90% concentrate diet. During Period 1, treatment × day interactions (P < 0.001) were observed for steer BW, average daily gain (ADG), and gain-to-feed ratio (G:F). Within all days, other than day 0, BW linearly decreased (P ≤ 0.01) as the percentage of juniper increased in the diet. When averaged across Period 1 (treatment × day, P = 0.64), DMI linearly decreased (P < 0.001) as juniper increased. Steer ADG linearly decreased (P ≤ 0.005) between days 0 to 14 and d 28 to 42, tended to linearly decrease (P = 0.09) between d 14 to 28, and tended to quadratically decrease (P = 0.07) between days 42 to 56. Steer G:F linearly decreased (P < 0.001) between days 0 to 14 and quadratically decreased (P = 0.02) between days 42 to 56. During Period 2, treatment × day interactions (P ≤ 0.04) were observed for steer BW, DMI, ADG, and G:F. No differences (P ≥ 0.13) within day were observed for steer DMI, but ADG increased linearly (P < 0.001) between days 84 to 98 and tended to increase quadratically (P = 0.07) between days 98 to 112 with prior juniper inclusion level. Steer G:F increased linearly (P = 0.001) and quadratically (P = 0.02) between days 84 to 98 and days 98 to 112, respectively, with prior juniper inclusion level. Overall, serum chemistry did not indicate negative health issues. Collectively, results suggested that while juniper has less dietary energy, replacing 33% of the alfalfa with juniper did not negatively affect steer growth performance and should be considered. Using up to 30% juniper in the diet did not negatively affect animal health; however, under the conditions of this study, supplemental protein would be required when juniper completely replaced alfalfa.
- Feedlot DietJuniperSecondary MetabolitesSerum ChemistrySteers