Effect of zeranol on sexual development of crossbred bulls.
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Three groups of 1/2 Simmental X 1/4 Brahman X 1/4 Hereford bull calves were used during two different years to study effects of zeranol on sexual development. At 154 d of age, half the calves were implanted with 36 mg zeranol and half, not implanted, served as controls. Implanted calves were reimplanted at 90-d intervals throughout the trial (9 mo) each year. Trial 1 was conducted with 24 calves and Trial 2 was conducted the following year with 10 bulls. Twenty-four days after weaning (200 d of age) and at 28-d intervals thereafter, bulls in drylot in Trial 1 were weighted, scrotal circumference (SC) was measured and an ejaculate of semen was collected by electroejaculation to determine puberty. At these times, bulls were given 200 micrograms of GnRH i.m. and blood was collected at 0, 1, 2, 3, 4 and 5 h after GnRH. Serum concentrations of LH and testosterone (TEST) were determined. At slaughter, testis weight, length and circumference and pubertal status were recorded. Bulls implanted with zeranol had smaller SC than control bulls during the entire 9-mo period (P less than .0001). More control bulls reached puberty than did implanted bulls (82.4 vs 23.5%, respectively; P less than .001). Control bulls had larger testis measurements at slaughter (P less than .0001). Implants did not alter total weight gain or ADG (P greater than .10).(ABSTRACT TRUNCATED AT 250 WORDS) (+info)
Natural occurrence of deoxynivalenol, 15-acetyl-deoxynivalenol, and zearalenone in refusal factor corn stored since 1972.
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Two samples of "refusal factor" corn, one stored frozen in Minnesota and one stored dry in Indiana since 1972 or 1973, were analyzed for the presence of Fusarium spp. and Fusarium toxins. Both samples were from corn refused by swine in Indiana from 1972 to 1973. Sample FS 808 (stored in Indiana) contained 20 ppm of deoxynivalenol (20 micrograms/g), 16 ppm of 15-acetyl-deoxynivalenol, 5 ppm of zearalenone, and 0.2 ppm of alpha-zearalenol. Sample FS 362 (stored in Minnesota) contained 3 ppm of deoxynivalenol, 1 ppm of 15-acetyldeoxynivalenol, and 0.3 ppm of zearalenone. The presence of 15-acetyl-deoxynivalenol is significant because it is the first report of it occurring naturally in refusal factor corn, and it may account in part for the refusal that could not be solely attributed to deoxynivalenol. (+info)
Formation of fusarenone X, nivalenol, zearalenone, alpha-trans-zearalenol, beta-trans-zearalenol, and fusarin C by Fusarium crookwellense.
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Fusarium crookwellense KF748 (NRRL A-28100) (isolated from dry rotted potato tubers in Central Poland) produced six mycotoxins on both rice and corn substrates at 25 degrees C. The metabolites detected were zearalenone, alpha-trans-zearalenol, beta-trans-zearalenol, fusarin C, and the trichothecenes fusarenone X and nivalenol. This is the first report of formation of alpha-trans-zearalenol, beta-trans-zearalenol, fusarenone X, and nivalenol by F. crookwellense. (+info)
Effects of zeranol on in vitro growth hormone release by lamb and rat pituitary cells.
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A series of experiments was conducted to evaluate the effect of zeranol on release and synthesis of growth hormone (GH) by anterior pituitary cells established in either static or continuous flow cultures. Young adult male rats, slaughter-age lambs and juvenile lambs were used as sources of pituitary cells. In static primary cell cultures, no consistent effect of zeranol at 10(-7), 10(-9) or 10(-11) M was demonstrated by either rat or ovine cells. Rat pituitaries established in perifusion culture chambers showed no repeatable response to zeranol. Dissociated cells from lambs established in perifusion culture, however, had significant increases in release of GH in response to 37% of zeranol pulse exposures. When dissociated cells from juvenile lamb pituitaries were used, up to 10-fold increases in GH release consistently were measured within minutes of exposure to zeranol. (+info)
Rate, composition and efficiency of growth in feedlot steers reimplanted with growth stimulants.
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Eighty Charolais-cross steer calves (283 kg) were fed a moderately high-energy (2.89 Mcal ME/kg) diet for 189 d to examine the effects of reimplantation of 36 mg of zeranol (Ralgro) or 200 mg progesterone plus 20 mg estradiol benzoate (Synovex-S) on the rate, composition and efficiency of gain, skeletal size and carcass parameters in a comparative slaughter trial. The implant treatments included unimplanted controls (C), Ralgro initially (R1), Synovex-S initially (S1), Ralgro initially and a reimplant at 84 d (R2) and Synovex-S initially and a reimplant at 84 d (S2). Both implants increased (P less than .06) gains by 8.1% from 0 to 84 d. Ralgro and Synovex-S increased (P less than .01) daily gains by 11.5% and 25.2%, respectively, from 84 to 189 d. The duration of the response to a single implant appeared to be in excess of 140 d; thus, reimplantation did not further increase daily gains. Reimplantation did improve (P less than .05) feed utilization in Ralgro implanted steers, however. Ralgro and Synovex-S increased (P less than .01) the rate of empty body (EB) protein accretion by 14.1% and 24%, respectively, without affecting EB fat growth. The efficiency of protein gain per unit protein (P less than .05) or energy intake (P less than .04) was improved, but the efficiency of energy gain per unit energy intake was not affected by implantation. Carcass weights of implanted steers were 5% greater (P less than .04) when adjusted to an equal carcass fatness. Both growth stimulants increased hip height (P less than .02), wither height (P less than .08) and body length (P less than .08) over C steers at slaughter. (+info)
Effect of sequential implanting with zeranol on steer lifetime performance.
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Three trials involving 513 exotic crossbred steers were conducted to determine the effect of zeranol implanting in the suckling and growing phases on subsequent feedlot performance and carcass characteristics. Treatments were 1) unimplanted control, 0000; 2) implanted twice in the finishing phase, 00II; 3) implanted in the growing phase and twice in the finishing phase, 0III; 4) implanted in the suckling phase and twice in the finishing phase, I0II; 5) implanted in the suckling and growing phases with a single implant in the finishing phase, III0; and 6) implanted in the suckling and growing phases and twice in the finishing phase, IIII. Implanting in the suckling period did not significantly affect preweaning gain. Implanting in the growing period produced a treatment x trial interaction (P less than .05), but zeranol increased gains by an average of 8.4% over the three trials. Growing period gain was not influenced by implanting during suckling. Implanting twice during the finishing period increased gain (P less than .05) over unimplanted and III0 steers. Finishing gain was not influenced by previous suckling and(or) growing implant treatment. Lifetime ADG of steers was increased (P less than .05) by all implant treatments compared with unimplanted controls. Zeranol tended (P = .14) to improve feed conversion in the finishing phase. All implant treatments increased hot carcass weight (P less than .05), and all but III0 reduced fat deposition, as indicated by lower quality grade (P less than .05). Other carcass characteristics were not significantly affected by treatment. These trials demonstrated that implanting in the suckling and(or) growing phases of production did not reduce performance in the finishing phase. (+info)
Influence of frame size and zeranol on growth, compositional growth and plasma hormone characteristics.
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A 2 X 2 factorially arranged trial was conducted to compare effects of implant (zeranol) and frame size on weight and compositional gain, and plasma hormone concentrations. Angus, Charolais X Hereford and Hereford X Angus yearling steers (34 steers averaging 270 kg body weight) were randomly assigned to treatments of small (SF) vs large frame (LF) and implant (I) vs no implant (NI). Steers were implanted at 0 and 97 d and individually fed an 81% whole shelled corn and 11.5% corn silage-based diet (dry basis) for a 175-d period. Shrunk weights and body measurements for frame size determination were taken initially and at approximately 28-d intervals; blood was collected via venipuncture at 14-d intervals for analyses of insulin (IN), triiodothyronine (T3), thyroxine (T4) and glucose concentrations. Steers were also counted in a whole body counter for measurement of 40K content and prediction of whole body protein and fat. The I steers showed an improvement (P less than .05) in daily gain regardless of frame size for the total trial. The I LF steers required 18% more dry matter to attain higher daily gain for 97 to 175 d; I steers were more efficient (P less than .05) at converting dry matter to gain during 0 to 97 d and 0 to 175 d. Daily fat deposition was increased (P less than .05) in I steers, while protein deposition was not affected by I. Plasma IN concentrations were numerically elevated (P less than .10) in I steers regardless of frame size, during the initial 97 d. Implant did not influence (P greater than .10) plasma T3, T4 and glucose concentrations regardless of frame size. Steers responded differently to zeranol implant over time regarding plasma T4 concentrations (P less than .003). Steers differing in frame size responded similarly in rate of gain, in feed conversion and in patterns of plasma insulin concentrations to zeranol implants. (+info)
Anabolic effects on rate, composition and energetic efficiency of growth in cattle fed forage and grain diets.
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The effects of anabolic implants on rate, composition and energetic efficiency of growth were determined in steers fed diets varying in forage and grain content. Santa Gertrudis-cross steers averaging 337 kg were group-fed (n = 72) or individually fed (n = 45) ad libitum one of three diets and either not implanted or implanted (90-d intervals) with Ralgro or Synovex-S implants. Steers were fed to a similar empty body weight (463 kg). Initial empty body composition of individually fed steers was determined via D2O dilution, and final composition of all steers was determined by carcass specific gravity. Rate of empty body gain increased (P less than .05) from 695 g/d for nonimplanted steers to 798 and 844 g/d for Ralgro- and Synovex-implanted steers. Anabolic implants increased (P less than .01) daily empty body protein gain from 91 to 119 and 133 g for Ralgro and Synovex, an increase of 31 and 46%, respectively. The fraction of protein in empty body gain increased (P less than .01) from 13.8% to 15.6 and 15.9%, and the percentage of fat in empty body gain decreased (P less than .01) from 41.7% to 32.9 and 31.3% with Ralgro and Synovex, respectively. Daily rates of protein deposition increased at a decreasing rate, and rates of fat deposition increased at an increasing rate with increasing rate of empty body gain. Implanted steers deposited more protein and less fat at any rate of growth; the magnitude of this shift in nutrient partitioning from fat to protein growth increased with rate of growth.(ABSTRACT TRUNCATED AT 250 WORDS) (+info)