SHORT COMMUNICATION: Management program for steers grazing toxic fescue alters activity

Abstract

Objective: The objective was to assess activity of steers grazing tall fescue pastures varying in toxicity with and without a combination management practice including supplemental feed, ionophore, and a steroidal implant. Materials and Methods: Activity of steers was monitored using IceQube (IceRobotics Ltd., Edinburgh, UK) accelerometers. Steers grazed 1 of 15 pastures differing in ergovaline (EV) in spring 2016. For 7 pastures, steers were offered mineral-only (MIN) management (MGMT). In the remaining pastures, steers received a cumulative (CM) MGMT strategy including 1% BW, 1:1 corn gluten feed:soybean hulls, 150 mg/head per day monensin, and a steroidal implant containing 40 mg of trenbolone acetate, 8 mg of estradiol, and 29 mg of tylosin tartrate. Physical activities—lying bouts, steps, and standing time—were reported in 2 periods: period 1 (27 d) and period 2 (26 d). Results and Discussion: Period 1 lying bouts were not different for MGMT (P = 0.11) or EV (P = 0.26). Period 2 lying bouts exhibited a MGMT × EV interaction (P = 0.02). Time steers spent standing was not different between CM and MIN during period 1 (P = 0.79) but differed during period 2 (P < 0.001). During period 2, CM steers exhibited less time standing and greater lying bouts. Implications and Applications: Behavioral changes due to EV and MGMT appeared more prevalent during period 2 when warmer weather and changing forage quality would be expected to worsen the effects of fescue toxins. The CM may elicit greater satiety or reduce heat stress. Strategies that improve productivity of cattle on toxic fescue may also improve welfare as expressed through physical activity changes.