Previous studies have shown that Ralgro implants administered at 30 to 90 days of age increase weaning weight in suckling steer calves by 24 lb. (Mader et al., 1985) and 23 lb. (Gill et al., 1986). However, these and other peer-reviewed research results from experiments conducted in the U.S. were completed nearly three decades ago. Beef cattle genetics in the U.S. have changed dramatically during this time period. Specifically, aggressive selection for growth, milk yield and muscling has occurred since 1985. Consequently, it is possible that the response to anabolic implant compounds may have changed as well. The objective of this experiment was to determine the impact of a Ralgro implant administered at 30 to 90 days of age on suckling phase growth rate and weaning weight. A total of 154 suckling steer calves weighing 254 lb. at branding (approximately 30 to 90 days of age) from two locations were used. Two hundred nine cow/calf pairs grazed primarily bermudagrass pastures near Valiant, Oklahoma, at the Mac Lindley Research Station while 106 cow/calf pairs grazed primarily native grass rangeland at the Crosstimbers Research Station near Stillwater, Oklahoma. Cows and calves were sired by Angus bulls. Within location, steer calves were stratified by dam age, then randomly assigned to two experimental treatments; implanted with Ralgro (77 animals) and no implant (98 animals). The steers were weighed at the time of branding/implanting and again at weaning 134 days later.

  • Implanted steers gained 20 lb. more body weight between the branding and weaning dates compared with nonimplanted steers.
  • This resulted in a tendency for a 4% increase in weaning weight and an 8% increase in 134-day body weight gain.

Ralgro growth-promoting implants remain an effective and economical method to increase performance of suckling steer calves, and the response is similar to research results published in the 1980s.