Effects of implants on daily gains of steers wintered on dormant native tallgrass prairie, subsequent performance, and carcass characteristics.

Abstract

Fall-weaned crossbred steer calves (n = 300; 184 +/- 2.9 kg) received either no implant (Control) or were implanted with Synovex-C (SC = 10 mg estradiol benzoate + 100 mg progesterone), Synovex-S (SS = 20 mg estradiol benzoate + 200 mg progesterone), or Revalor-G (RG = 8 mg estradiol-17beta + 40 mg trenbolone acetate) to determine the effects of implants on weight gain during winter grazing on dormant tallgrass prairie, subsequent grazing and finishing performance, and carcass characteristics. Steers grazed two dormant tallgrass prairie pastures from October 16, 1996, until March 29, 1997 (164 d), and received 1.36 kg/d of a 25% CP supplement that supplied 100 mg of monensin/steer. Following winter grazing, all steers were implanted with Ralgro (36 mg zeranol) and grazed a common tallgrass prairie pasture until July 17 (110 d). After summer grazing, all steers were implanted with Revalor-S (24 mg estradiol-17beta + 120 mg trenbolone acetate), and winter implant treatment groups were equally allotted to four feedlot pens. Steers were harvested November 17, 1997, after a 123-d finishing period. Daily gains during the winter grazing phase averaged .28, .32, .32, or .35 kg/d, respectively, for Control, SC, SS, or RG steers and were greater (P < .01) for implanted steers than for Controls. Summer daily gains were similar (1.05 +/- .016 kg/d; P > or = .61) for all treatment groups. Feedlot daily gains were also similar (1.67 +/- .034 kg/d; P > or = .21), with implanted steers weighing 14 kg more than Control steers (P = .05) at harvest, despite similar management during summer grazing and feedlot phases. Control steers tended (P = .06) to have lower yield grades. There were no differences (P = .99) in marbling between implanted and nonimplanted steers. Steers implanted during the wintering phase had increased skeletal and overall (P < .01) carcass maturities compared with nonimplanted steers, which resulted in more "B" and "C" maturity carcasses. Because carcass maturity score affects quality grade, the increased maturities of implanted steers resulted in a $9.04 decrease in carcass value/100 kg (P < .01) compared with Controls. The results of this study indicate that growth-promoting implants are efficacious for cattle wintered on dormant native range despite low daily gains. This increased weight is maintained through the summer grazing and feedlot phases; however, the benefit of the increased weight may be offset by decreased carcass quality grade and value due to increased carcass maturity.

MEAT SCIENCE AND MUSCLE BIOLOGY SYMPOSIUM—Anabolic implants and meat quality1

“…Roeber et al (2000) found skeletal maturities similar to nonimplanted controls when the initial combination implant was administered at 59 d after the beginning of the trial compared with implanting at 0 d, which advanced skeletal maturities by 11 or 16 points. Paisley et al (1999) evaluated the effect of various estrogenic implants (i.e., Synovex-C, Synovex-S [Zoetis, Florham Park, NJ], or Revalor-G [Merck Animal Health, Summitt, NJ]) in steers during wintering period on skeletal maturity. The steers were harvested at about 22 mo of age and skeletal maturity was advanced by 20 to 24% with the use of estrogenic implants during the wintering phase.…”

Possible health impact of animal oestrogens in food

“…Nowadays, some preparations on the market show faster oestradiol release (Daxenberger et al, 2000), and other recent studies investigated higher dosages and shorter withdrawal periods. There were at least six publications in The Journal of Animal Science alone during 1999, that recommend repeated or multiple treatments of different combined preparations to achieve optimal growth promotion and nutrient retention (Duckett et al, 1999;Holzer et al, 1999;Paisley et al, 1999;Rumsey et al, 1999a,b;Smith et al, 1999). Such information is also available from the internet (NebGuide, 1997), but pharmacokinetic data have not been elaborated in any of these studies and published residue data from real-world treatments were not available.…”

“…The comparison of healthy prepubertal children with Turner syndrome girls highlights the important role of low oestrogen concentrations in childhood. In healthy, prepubertal girls transient signs of pseudo-precocious puberty were associated with accidental intake of oestrogens (Pasquino et al, 1982). The concentrations of oestrogens that regulate growth and development during childhood are very low, but possible effects of dietary oestrogens on such low concentrations are unclear.…”

Hormone contents in peripheral tissues after correct and off‐label use of growth promoting hormones in cattle: Effect of the implant preparations Finaplix‐H®, Ralgro®, Synovex‐H® and Synovex Plus®

“…The manufacturers' instructions provided with the preparations, for instance, do not contain any explicit warning against multiple application. Even in the scientific literature, repeated or multiple treatment of different combined preparations is often recommended to achieve optimal results (4)(5)(6)(7)(8)(9).…”