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United States Department of Agriculture

Agricultural Research Service

Title: Performance and Carcass Characteristics of Feedlot Steers: Effects of Delayed Implanting and Programmed Feeding During the Growing Period.

Authors
item Scaglie, G. - TAES
item Greene, L. - TAES
item Mccollum, F. - TAES
item Cole, Noel
item Montgomery, T. - WTAMU

Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 4, 2004
Publication Date: April 1, 2004
Citation: Scaglie, G., Greene, L.W., Mccollum, F.T., Cole, N.A., Montgomery, T.H. 2004. Performance and carcass characteristics of feedlot steers: effects of delayed implanting and programmed feeding during the growing period. Professional Animal Scientist. 20:162-169.

Interpretive Summary: Anabolic growth agents are routinely used in beef cattle to increase production efficiency and decrease production costs. Restricting feed intake of feeder cattle may have beneficial effects on production efficiency. These management practices may also affect how animals deposit fat and subsequently the quality grade of the carcass. Therefore, this study was conducted to evaluate the effects of implanting regimen and restricted feed intake on production efficiency, carcass characteristics, and marbling development in beef cattle. Four treatments were applied to 96 steers during the growing period: Treatments were the following: 1) implanted (Synovex-S) and limit-fed to gain slowly, 2) implanted and fed to gain fast, 3) not implanted and fed to gain slowly and 4) not implanted and fed to gain fast. Steers were fed a 25% roughage diet for 60 to 88 days and then were transitioned to a high concentrate finishing diet. Implant treatments did not affect subsequent daily gain or gain efficiency during the finishing period. Treatment did not affect marbling score, quality grade, fat thickness, or yield grade. Feeding steers for a slow rate of gain during the growing period improved gain efficiency in the finishing period. When harvesting at a constant external fat, a greater percentage of the implanted steers fed to gain slowly graded USDA Choice compared to those implanted and fed to gain fast. The non-implanted steers were intermediate in USDA Choice quality grade regardless of rate of gain during the growing period. These results show that implant and feeding level prior to the start of the finishing period affects performance and carcass quality during the finishing period.

Technical Abstract: Ninety-six growing steers (230 kg) were assigned to 12 pens in a completely randomized block design and fed a grower diet. Implant (Synovex-S or no implant) and programmed feeding to gain slow or fast were randomly assigned to a pen of steers in a 2 x 2 factorial arrangement. Steers were fed a diet consisting of 65% steam rolled corn, 25% alfalfa pellets and 10% supplement. After 88 and 60 d for steers fed to gain slow or fast, respectively, steers were transitioned to ad libitum consumption of a high concentrate finishing diet (10% roughage). Steers were harvested when the average fat thickness of the steers in the pen was 12 mm. There was an interaction between implant and rate of gain for daily gain (P = 0.10) and gain efficiency (P = 0.053) during the growing period. Implant treatments did not affect subsequent daily gain or gain efficiency during the finishing period. Steers fed to gain fast during the growing period gained more (P = 0.066) than those fed to gain slow from reimplant to harvest of the finishing period (1.21 vs. 0.97 kg/d). Treatment did not affect marbling score, quality grade, fat thickness or yield grade. In steers fed to gain slow in the growing period, implanting increased Longissimus dorsi area compared to those not implanted but not when steers were fed to gain fast during the growing period. Feeding steers for a slow rate of gain during the growing period improved (P = 0.013) gain efficiency in the finishing period (0.200 vs 0.155 gain/feed). When harvesting at a constant external fat, a greater percentage of the implanted steers fed to gain slow graded USDA Choice compared to those implanted and fed to gain fast. The non-implanted steers were intermediate in USDA Choice quality grade regardless of rate of gain during the growing period. These results indicate that implant and feeding level prior to the start of the finishing period affects performance during the finishing period.

Last Modified: 9/20/2014
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