Influences of implant hormone strategy on growth performance of calf-fed Holstein steers fed in excess of 300 days

Abstract

The objective was to compare the effects of 4 implant management strategies involving long-duration implants on growth performance and dietary NE use of calf-fed Holstein steers. A total of 192 calves were used in a 335-d experiment. Treatments were as follows: S1S1 = Synovex ONE (200 mg of trenbolone acetate and 28 mg of estradiol benzoate; Zoetis Animal Health, New York, NY) on arrival and Synovex ONE on d 168; S1SP = Synovex ONE on arrival and Synovex Plus (200 mg of trenbolone acetate and 28 mg of estradiol benzoate; Zoetis Animal Health) on d 224; SCE = Synovex C (100 mg of progesterone and 28 mg of estradiol benzoate; Zoetis Animal Health) on arrival and Encore (43.9 mg of estradiol; Elanco Animal Health, Greenfield, IN) on d 112; and SCS1 = Synovex C on arrival and Synovex ONE on d 112. Steers implanted with Synovex ONE on arrival had greater ( P < 0.01) ADG, G:F, and performance-estimated NE g (peNE g ) than those receiving a Synovex C implant. From d 112 to 224, steers in the SCS1 group had greater ( P < 0.01) ADG than steers in the SCE group. Differences in ADG between SCE and SCS1 were not appreciable ( P = 0.14) during the final 111-d period of the study. Cattle in the S1S1 group had greater ( P < 0.01) ADG and DMI than cattle in the S1SP group during the second 112-d period but decreased ( P < 0.01) G:F and peNE g during the final 111-d period. Implant strategies that incorporate long-acting implants to avoid terminal implantation when animals have greater days on feed did not improve calf-fed Holstein steer growth performance. Indeed, using a noncoated hormonal implant during the late finishing phase (implantation at 224 d on feed) increased overall peNE g , representing greater efficiency on cattle growth performance.