Authors : S.E. Kitts , D.L. Harmon , E.S. Vanzant and K.R. McLeod
Abstract: The objective of the current study was to ascertain the effects of Chlortetracycline (CTC) and Revalor-S, both alone and in combination, on growth performance and carcass merit of finishing beef steers. Ninety-six English-Continental crossbred steers (401 kg ? 1) were blocked according to Body Weight (BW) and pens were assigned randomly to a 2 x 2 factorial arrangement of treatments of either 0 or 39.6 ppm (DM basis) CTC/d, with and without Revalor-S. Steers received ad libitum amounts of a 90:10 concentrate-forage diet formulated to provide 105% of the Metabolizable Protein (MP) requirement for steers gaining 1.60 kg d 1 during d 1-62, and 1.20 kg d 1 during d 63-139. Steers were slaughtered on d 126 or 140 to determine carcass quality characteristics. Growth and feedlot performance data were adjusted to reflect a 139-d feeding period. During d 1-84 of the experiment, Revalor-S increased average daily gain (ADG; p 0.01) by an average of 25% and efficiency of gain (p 0.004) by an average of 27% relative to non-implanted steers. There were no effects (p 0.13) of CTC on ADG or feed efficiency during d 1-84; however, dry matter intake (DMI) decreased (p 0.01) during d 29-56 for steers receiving CTC compared to those receiving no CTC. During d 85-139, there was an interaction (p 0.07) between CTC and implant for ADG and feed efficiency. In the absence of CTC, implanted steers gained an average of 0.74 kg d 1 more BW (p 0.02), and 60% more efficiently (p 0.02) than non-implanted steers. However, in the presence of CTC, there was no effect (p 0.13) of implant. Treatment did not affect carcass quality (p 0.22). Across the 139-d feeding period, implant increased ADG (p<0.0001), while CTC decreased DMI (p 0.02). Efficiency of BW gain was greater for implanted steers in the absence, but not in the presence, of CTC (CTC x implant interaction, p 0.03). This experiment shows that Revalor-S increases ADG, however, efficiency of gain is partially diminished when subtherapeutic levels of CTC are fed in conjunction with this implant.
S.E. Kitts , D.L. Harmon , E.S. Vanzant and K.R. McLeod , 2006. Effects of Chlortetracycline (CTC) and Revalor-s? on Growth Performance and Carcass Quality Traits of Finishing Beef Steers. Journal of Animal and Veterinary Advances, 5: 70-76.