17a Trenbolone [KLH]

Trenbolone acetate (TbA) is a potent synthetic anabolic steroid that was approved by the FDA as a growth promoter in beef cattle in 1987. Given the endocrine-modulating activity of TbA and its metabolites in all vertebrates, a sensitive and reliable analytical method is needed to detect TbA and related residues in environmental matrices. We have developed a method that incorporates solid phase extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of the three major TbA metabolites (trendione, 17 beta-trenbolone, 17 alpha-trenbolone) in total suspended particulate matter (TSP) samples. Sample preparation involved pressurized liquid extraction followed by cleanup on solid-phase extraction cartridges. The procedure was optimized to obtain maximum recovery and minimum signal suppression/enhancement from matrix effects. Analytes were separated with a Phenomenex Gemini-NX C18 analytical column (150 mm x 2.0 mm, 3 mu m particle size) using an aqueous methanol gradient at a flow rate of 0.2 mL/min. Column effluent underwent positive electrospray ionization (ESI). Two or more diagnostic product ions were acquired from analyte specific precursor ions for unambiguous confirmation and quantification. The method detection limit was 3.27-4.87 ng/g of particulate matter (PM). Method accuracy, determined with analyte recoveries, ranged between 68% and 117%, and method precision, expressed as relative standard deviation, was below 15% at spiked levels of 6.67, 33.3, and 167 ng/g PM. Analysis of TSP samples demonstrated the presence of the target species associated with PM in the vicinity of beef cattle feeding operations. (C) 2011 Elsevier B.V. All rights reserved.

Fifty four cyclic gilts were randomly selected and uniformized according to genetic background, litter of origin, weight gain, backfat, number of cycles and clinical score. Gilts were alloted to one of two groups fed isocaloric, isoproteic and isolysinic diets. Two energy sources were tested: corn starch (T1) and soybean oil (T2). Second estrus was synchronized with oral allyl-trenbolone, so that insemination was carried out at third estrus. Indweeling catheters were implanted by non- surgical technic in 21 gilts, which were submitted to consecutive blood samplings for glicose and insulin determination. Timing of ovulation was estimated by means of ultrasonography. All gilts were slaughtered at an average gestation lenght of 28.6 days. Starch- fed gilts (T1) showed higher ovulation rates than T2 gilts (16.52 vs 14.70; P < 0.01). There was no effect of treatments on pregnancy rate and embryo survival. Results indicate it is possible to manipulate reproductive efficiency through diet even in anabolic experimental models like cyclic gilts. Feeding starch as main energy source during pre-mating flushing phase improved reproductive efficiency of cyclic gilts.