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United States Department of Agriculture

Agricultural Research Service

Title: Effect of Delaying Implant and Programmed Rate of Gain on Performance and Caracass Characteristics of Yearling Beef Steers

Authors
item Scaglie, G - TAES
item Greene, L. - TAES
item Mccollum, F. - TCE
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. Effect of delaying implant and programmed rate of gain on performance and caracass characteristics of yearling beef steers. Professional Animal Scientist. 20:170-177.

Interpretive Summary: Anabolic growth implants are routinely used in beef cattle to improve production efficiency and decrease costs of production, however they may have adverse effects on carcass quality grade. In contrast, programmed feeding cattle to achieve specific rate of gain may improve quality grades. Therefore, this experiment was conducted to determine the effect of programming the rate of gain and delaying the first implant in feedlot steers on feedlot performance and carcass characteristics. Steers were put in the experimental feedlot and the following treatments were applied: 1) implanted on d 1 and given ad libitum access to feed, 2) implanted on day 1 and limit fed to gain 1.4 kg per day for 62 days, 3) not implanted until day 63 and given ad libitum access to feed (fast rate of gain), or 4) not implanted and limit-fed to gain 1.4 kg/d during the first 62 d of the feeding period. By experimental design, average daily gain was greater for steers fed to gain fast (1.96 kg) than those fed to gain slow (1.27 kg) from day 1 to 62. Restricting feed intake during the first 62 d of the finishing period increased daily gain an d gain efficiency during the remaining portion of the finishing period. Implanted steers fed to gain fast had the least carcass fat and non-implanted steers limit-fed to gain slow had the most carcass fat. Marbling score, yield grade, fat thickness, and ribeye area were not affected by experimental treatment. Reducing daily gain during the first 62 d of the finishing period, increased gain efficiency throughout the experiment resulting in 2,650 grams less nitrogen and 461 grams less phosphorus used by each steer during the first part of the finishing period.

Technical Abstract: This experiment was conducted to determine the effect of programming the rate of gain and delaying the first implant in feedlot steers on feedlot performance and carcass characteristics. Ninety-six steers (average BW = 335 kg) were allotted to 12 pens in a completely randomized design with a 2 x 2 factorial arrangement of treatments. Factors were: a) implant on d 1 or no implant, and b) ad libitum access to feed (fast rate of gain) or programmed-fed for a target gain of 1.4 kg/day (slow rate of gain) during the first 62 day of the feeding period. On day 63 all steers were implanted with Revalor-S and allowed ad libitum access to feed. External fat was estimated by ultrasound on day 1, 62, and 117. Steers were harvested when external fat was predicted to be 12 mm. The 9th to 11th rib section was dissected to determine proportion of bone, fat, and lean. By experimental design, average daily gain was greater (P < 0.05) for steers fed to gain fast (1.96 kg) than those fed to gain slow (1.27 kg) from day 1 to 62. During days 63 to 116, daily gain and gain efficiency for steers programmed-fed to gain slow (2.24 kg and 0.194, respectively) were greater (P < 0.05) than for steers fed to gain fast (1.67 kg and 0.140, respectively). Restricting feed intake during the first 62 days of the finishing period increased daily gain during the remaining portion of the finishing period. Gain efficiency was improved (P = 0.097) throughout the entire finishing period by reducing gain during the first 62 days of the experiment. An interaction (P = 0.024) occurred for fat weight from the 9th to 11th rib section. Implanted steers fed to gain fast had the least fat and non-implanted steers fed to gain slow had the most fat. Marbling score, yield grade, fat thickness, and longissimus dorsi area was not affected by experimental treatment. Correlation coefficients between ultrasound measurements of external fat and marbling score increased the closer the measurement was taken to the harvest date. Reducing daily gain during the first 62 d of the finishing period resulted in 2,650 grams less nitrogen and 461 grams less phosphorus required per steer during the first part of the finishing period.

Last Modified: 11/23/2014
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