Effect of Anabolic Implants on Serum Mineral Concentrations in Large and Small Frame Steers


Authors: Theresa Craig Solis*, L.W. Greene, F.M. Byers and G.T. Schelling (* Former name of Dr Theresa Craig)
Texas A&M Univ. and Texas Agr. Exp. Sta., College Station.

Published: J. Anim. Sci. 65 (Suppl. 1); 29 (Abstr) 1987

Sixty-four crossbred steer calves, ages 8 to 11 mo, of large (L; n=29) and small (Sm; n=35) mature sizes were individually fed a high grain finishing diet to determine the effects of implant on serum Mg, Ca, Zn and Fe concentrations.  Initial weights for L and Sm were 295.1 and 235.2 kg, respectively.  Small and L cattle were randomly assigned to a control, no implant (C), Ralgro (R; 36 mg zeranol),or Synovex (S; 20 mg estradiol-17 beta, 200 mg progesterone) treatment.  Serum samples were taken 28 d post-implant.  Implant treatments, C, R, and S, did not change (P>.10) serum concentrations of Mg (1.2, 1.4 and 1.4 mg/dl, respectively), Ca (9.0, 9.0 and 8.8 mg/dl, respectively) and Fe (.57, .58 and.60 mg/dl, respectively).  Serum Zn levels were higher (P<.10) for C vs S, 88.6 vs 79.4 μg/dl, and steers implanted with R were intermediate, 83.4 μg/dl.  Frame size, L vs S, did not affect (P>.10) serum Mg (1.4 vs 1.3 mg/dl), Ca (9.0 vs 8.9 mg/dl), Zn (88.1 vs 79.5 μg/dl), and Fe (.59 vs .58 mg/dl) concentrations.  There was no interaction between mature size and implant treatment for serum Ca, Mg, or Zn.  However, an interaction of main effects (P<.05) was present for serum Fe concentrations.  The interactions existed due to a 19.7%, non-significant, decrease (P>.10) in serum Fe in L steers implanted with S and a 39.6% increase (P<.05) in Sm steers implanted with S.  Within each mature size group, the serum Fe of steers implanted with R were intermediate between C and S.  Frame size had no effect on serum mineral concentration, but steers implanted with Synovex had lower serum Zn concentrations than control steers.