Effect of trenbolene acetate/estradiol implants and estrus suppression on growth performance and carcass characteristics of beef heifers

Abstract

. 1997. Effect of trenbolene acetate/estradiol implants and estrus suppression on growth performance and carcass characteristics of beef heifers. Can. J. Anim. Sci. 77: 325-328. The effects of estrus suppression (none, oral melengestrol acetate (0.4 mg d -1 ) or ovariectomy via Willis spay technique) and an anabolic implant (none or Synovex Plus ® ) on growth performance and carcass characteristics were determined using 90 beef heifers of composite breeding in a 2 × 3 factorial experiment conducted in the last 50 d before slaughter. Spaying caused no morbidity or mortality and resulted in average daily gains (1.37 kg d -1 ) comparable to heifers fed melengestrol acetate (1.33 kg d -1 ). Implanting improved (P < 0.05) feed efficiency and increased (P < 0.05) animal gain, ribeye area, carcass weight and yield and reduced (P < 0.05) intramuscular fat deposition but estrus suppression did not. Method of estrus suppression did not influence (P > 0.05) carcass traits. Spaying and implanting represent an effective means of improving returns from heifers, even late in the finishing period.

Effect of growth-promoting technologies on Longissimus lumborum muscle fiber morphometrics, collagen solubility, and cooked meat tenderness12

“…Over the 75-d feeding period, use of GP technologies did not improve feedlot performance measures, which is in contrast to the plethora of literature that documents drastic improvements in these measures. When examining studies that utilize implant strategies that consist of a similar hormone dosage as the current study (200 mg trenbolone acetate/20 mg estradiol), heifer ADG and G:F can be increased by up to 50% and 31%, respectively (Herschler et al, 1995;Popp et al, 1997;Guiroy et al, 2002). In agreement with the current study, Garber et al (1990) found that implanting heifers with Synovex-H did not affect G:F; however, ADG was improved by the implant.…”

“…Garber et al (1990) reported that implanting heifers did not increase HCW or yield grade, but did report a 6% increase in LM area. Other studies indicate that anabolic implants can increase both HCW and LM area modestly by 8% (Herschler et al, 1995;Popp et al, 1997). When ZH was added to the GP program and compared to the CON carcasses, HCW, yield grade, and LM area were increased by 5%, 33%, and 18%, respectively.…”

The effect of anabolic implants on intramuscular lipid deposition in finished beef cattle

“…Longissimus muscle area of steers tended to be increased (P = 0.10) by implant but to a lesser extent (7%) than was observed in heifers. Heavier carcasses and larger LM areas have been reported previously from steers (Hermesmeyer et al, 2000) and heifers (Popp et al, 1997;Mader, 2000) implanted once with a mild or strong combination implant. A review by Dolezal (1997) reported that combination implants used in yearling steers produced the greatest increase in carcass weight and LM area.…”

Optimizing carcass value and the use of anabolic implants in beef cattle

“…A single implantation with an androgen, mild combination or strong combination implant has been shown to improve ADG and gain:feed in heifers when compared against nonimplanted controls (Duckett et al, 1997;Popp et al, 1997;Mader, 2000). However, the use of a single estrogen implant has been found to have no effect on these factors (Stobbs et al, 1988;Duckett et al, 1997;Mader, 2000).…”