Comparison of RALGRO to No Implant in Sucking Beef Calves at Pasture

By Norm Machell, D.V.M., Technical Services Veterinarian, Schering-Plough Animal Health - To measure the effect of a single RALGRO implant on weight gain in spring born calves in a herd in Saskatchewan through the summer of 1999.
calendar icon 29 December 1999
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Schering-Plough Animal Health


Calves born in the spring of 1999 were used in this study. As calves were handled for routine spring processing, each sequential pair of calves was individually weighed, and each one was randomly assigned to either the RALGRO or the No Implant study group. Subsequent to processing all calves were returned to their dams and commingled on summer pasture.

The producers at each farm were blind to treatments (they did not know which of the calves were implanted) and they maintained health records for all calves through the summer pasture season. At the end of summer calves in both herds were individually handled for fall processing and weighing. Individual spring and fall weights were used to calculate weight gain for each calf through the summer pasture season.

Herd Description

Location: Near Saskatoon, Saskatchewan
Test Animals: Cross bred steer and heifer beef calves
Number of Study Calves: 158 total; 79 RALGRO, 79 No Implant
Implant Date: May 5, 1999
Final Weight Date: October 13, 1999


Test Group Days on Test Average Initial Weight Average Final Weight Weight Gain Average Daily Gain
RALGRO 161 83.6 616.4 432.7 2.69
No Implant 161 184.6 601.8 417.2 2.59
RALGRO* Advantage: 15.5 lbs  


Calves implanted with RALGRO returned an average of 15.5 lbs of extra gain compared to non-implanted calves. This translates into an improvement in average daily gain of greater than 0.1 lbs per day. This finding is consistent with studies in the past where the average extra gain in RALGRO implanted calves is often in the vicinity of 20 extra lbs. compared to non-implanted calves.

Herd to herd variations in response to implanting can be attributed to a number of reasons including the quality of pasture and supplementation, genetic characteristics of the calves, length of pasture season, parasite loads and health status of the herd. The herd in this study was on a parasite control program and appeared to be in good overall health.

December 1999

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