Thesis - Open Access
Master of Science (MS)
Department / School
Terminal implant administration in beef steers often leads to decreased feed intake, leading to less growth. Our objective was to identify diet and management changes that can mitigate this decrease in feed intake. Single-sourced Angus x Simmental steers (n=27, initial BW= 385.1 ± 30.8 kg) were utilized in a completely randomized trial to assess the effects of animal movement and increased forage inclusion on rumination and feed intake after re-implanting. Steers were initially implanted with Synovex Choice (100 mg trenbolone acetate and 14 mg estradiol benzoate; Zoetis, Parsippany, NJ), then reimplanted 88 d later with Synovex Plus (200 mg trenbolone acetate and 28 mg estradiol benzoate). Steers had been consuming the finishing diet for approximately 88 d at the time of re-implanting. Steers were allocated into one of three treatment groups: CON) remained on a 1.43 Mcal/kg NEg diet and moved a shorter distance between the pen and working facility (0.43 km), ACT) remained on a 1.43 Mcal/kg NEg diet and moved a longer distance (1.05 km) to simulate movement in a larger feedlot and ACT + DIET) fed a 1.32 Mcal/kg NEg diet (increased forage inclusion) and travelled 1.05 km between the pen and working facility. Individual feed and water intake was collected using Insentec RIC feeders and waterers (Hokofarm, Marknesse, Netherlands). Individual rumination data was collected with SenseHub Beef (AllFlex Livestock Intelligence, Madison, WI). No significant differences among treatments were observed for overall dry matter intake, average daily gain, gain to feed ratio, or carcass traits. No treatment effect was observed for dry matter intake for 14 days post-reimplantation. A treatment by days on feed effect was observed for dry matter intake, where CON cattle consumed more feed than ACT + DIET on multiple days after reimplanting (P = 0.03). The ACT + DIET group ruminated ~65 minutes/day more (P = 0.02) than CON for 14 days after reimplantation. No differences in total water intake for 14 days (P = 0.38) or the cumulative period (P = 0.97) were observed. Activity (calculated number of minutes standing, walking, eating, drinking) was unaffected by reimplantation (P = 0.99). Increasing forage inclusion in the diet for 7 days after re-implantation did not mitigate feed intake depression, but increased rumination for multiple days after reimplanting. When reimplanting cattle, it is recommended to limit distance calves have to travel. Nutritional management strategies utilized in this experiment indicate that increasing forage inclusion increases rumination. Previous research suggests that increasing rumination decreases incidence of acidosis, however, further research must be conducted to determine the effects of increased forage inclusion on rumen pH post-reimplantation.
South Dakota State University
Kelly, Alexandria M., "Diet and Management Strategies to Mitigate Decreased Feed Intake Associated with Terminal Implant Administration in Finishing Beef Steers" (2023). Electronic Theses and Dissertations. 688.