The effects of implant strategy on finished body weight of beef cattle

Abstract

We summarized experimental data to quantify the change in final BW due to a particular implant strategy when cattle are adjusted to the same final body composition. The database developed for this study included 13 implant trials involving a total of 13,640 animals (9,052 steers and 4,588 heifers). Fifteen different implant strategies were used among these trials, including no implant (control), single implants, and combinations of implants. Individual carcass data collected at slaughter were used to calculate the adjusted final shrunk BW at 28% empty body fat (AFBW) for each treatment group within a trial, then the implant treatments were grouped into categories according to their effect on weight at 28% empty body fat (four groups for steers and two groups for heifers). All differences in AFBW between categories were significant (P < 0.01), indicating an incremental anabolic implant dose response in AFBW over unimplanted animals. Values for AFBW ranged from 520 kg in unimplanted steers to 564 kg in steers implanted and reimplanted with Revalor-S. For heifers, AFBW ranged from 493 kg in unimplanted heifers to 535 kg in heifers implanted and reimplanted with Revalor-H. After accounting for differences in mean BW and composition of gain, implanted steers and heifers had 4.2 and 3.1% higher apparent diet ME values, respectively. Increasing the anabolic implant dose increases the weight at which animals reach a common body composition. This study indicates that anabolic implant response is due to a combination of a reduced proportion of the DMI required for maintenance, reduced energy content of gain, and efficiency of use of absorbed energy.

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.…”

Exigências nutricionais de zebuínos: energia

“…Observa-se que, em animais castrados, a magnitude do aumento dos conteúdos corporais de gordura e, conseqüentemente, de energia, é maior, uma vez que animais castrados depositam, com mesmo peso vivo, mais gordura que animais inteiros. A menor deposição de gordura no corpo, seguida por maior concentração protéica do ganho de peso em animais inteiros, é explicada pela síntese e secreção dos hormônios androgênicos, substâncias esteróides com ação anabólica pronunciada no organismo animal (Guiroy et al, 2002). Como esses hormônios são sintetizados nas gônadas (testí-culos), animais castrados não apresentam o mesmo ímpeto anabólico dos animais inteiros e, conseqüente-mente, sintetizam menos proteína, sendo a energia disponível desviada para a síntese de gordura.Esse comportamento da composição corporal explica os maiores requerimentos de energia de bovinos castrados em relação aos inteiros.…”

Calving date and wintering system effects on cow and calf performance I: A systems approach to beef production in the Nebraska Sandhills

“…The experiment was designed to harvest all finished cattle when FT was visually estimated to be 1.27 cm. However, because of the imprecision of the estimation, cattle were harvested at differing degrees of FT. To account for differences in performance caused by dissimilar management among treatments FT, HCW and marbling must be adjusted to a common harvest endpoint (Guiroy et al, 2002;Tedeschi et al, 2004). Cattle from this study were compared at similar harvest endpoint following the procedure described by Griffin et al (2007).…”