WS Effects of administering Ralgro to Holstein calves during the hutch period on growth performance

Abstract Text: We hypothesized that early administration of a Ralgro implant to one day old Holstein calves will improve growth performance. One thousand two hundred and forty-eight one day old Holstein steer calves (initial BW 41.2 ± 0.2 kg) were utilized in a completely randomized block designed experiment with truck load serving as the block (6 loads).  On d 0, calves were individually weighed, tagged with an electronic identification tag, and vaccinated with Vision CD-T with Spur during initial processing.  Calves were randomly assigned within block to receive one of two treatments: 1) growth implant containing 36 mg Zeranol (n = 584) or no growth implant (n = 598). Calves were individually housed in wood hutches and provided ad libitum access to grain starter (17.2% CP, 4% fat and NEm 0.49 Mcal/kg and NEg 0.34 Mcal/kg) and water.  In addition, calves were offered two, 1.9 L bottles of milk replacer two times daily (25.5 % CP and 22.5% fat, DM basis).  Implanted calves had greater DMI (P < 0.01) compared to non-implanted calves over the 92-d period.  Likewise, ADG was greater (P < 0.01) when calves were implanted at 1 day of age versus non-implanted calves.  However, due to the increase in DMI and ADG for calves receiving implants, G:F tended to differ (P= 0.08) between treatments.  Overall, implanting calves with 36 mg of Zeranol did not appear to have any adverse effects on intake or feed efficiency in one day old calves during the hutch phase and improved ADG by 6%. 

Keywords: Calf, Growth, Hutch, Implants, Zeranol