Use Of Growth-promoting Agents Research Articles

Development of a Uniform Biomarker Signature in Calves Heart and Lung to Detect the Abuse of Different Anabolic Substances

The use of growth-promoting agents in food-producing animals is economically very attractive for farmers. Due to proven side effects of substance residues for the consumer, the administration of growth-promoting agents is forbidden in the EU and this ban is well controlled.

Metabolomic analysis of swine urine treated with β2-agonists by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry

The illegal use of β2-agonists in livestock production was previously detected by efficient methods based on mass spectrometry to control the residues of these drugs. Nevertheless, such methods still remain a challenging task for authorities who monitor these residues because the use of “cocktails” composed of mixtures of low amounts of several substances as well as the synthesis of new compounds of unknown structure prevent efficient prevention of illegal use of growth-promoting agents. Here, we outlined a metabolomics-based strategy for detecting the use of “cocktails” composed of mixtures of low amounts of three β2-agonists via urine profiling. Urine profiles of controls and swine treated with mixture of low amounts of three substances (clenbuterol, salbutamol, and ractopamine) were analyzed with ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. The metabolic differences between controls and β2-agonists-treated groups were compared using multivariate data analysis. Fourteen metabolites were identified related with the β2-agonists treatment, while two co-biomarkers, 2-indolecarboxylic acid and fluorometholone acetate, either in single or “cocktails” of low-dose mixture of clenbuterol, salbutamol, and ractopamine, could be considered as diagnostic markers for the detection of illegal use of β2-agonists. The results of depletion study demonstrated that it is practical to use the markers for monitoring of β2-agonists.

The physiological way: Monitoring RNA expression changes as new approach to combat illegal growth promoter application

The use of growth-promoting agents in food-producing animals is forbidden in the European Union (EU). Therefore a strict control programme has been developed, detecting residues of all known growth-promoting agents using chromatographical methods in combination with mass spectrometry or immunoassays. New designed xenobiotic substances or hormone cocktails are difficult to identify with these methods and therefore the development of new sensitive test methods is important. A promising indirect approach is the detection of physiological effects of the administered growth promoters on the molecular level using 'omic' technologies. The analysis of the transcriptome on mRNA and miRNA level and thereby identifying biomarkers for the use of anabolic agents is one possible strategy for developing a new screening method. This paper describes the technologies available for gene expression profiling and summarizes the efforts made in the analysis of the transcriptome in order to identify potential gene expression biomarkers for the use of growth promoters in cattle.

Antibiotic Resistance and Hypermutability of Escherichia coli O157 from Feedlot Cattle Treated with Growth-Promoting Agents

In a longitudinal study (165 days), we investigated the effect of growth-promoting agents (monensin and trenbolone acetate–estradiol) and an antibiotic (oxytetracycline) on the incidence in feedlot steers of Escherichia coli O157, including antibiotic-resistant and hypermutable isolates. Eighty steers in 16 pens were treated with eight combinations of promoters, and each treatment was duplicated. Fecal samples were collected at nine different sampling times for detection of E. coli O157. Overall, 50 E. coli O157 isolates were detected in treated animals, and none were found in untreated animals. Compared with untreated controls, there was a significant association between the utilization of growth-promoting agents or antibiotics and the shedding of E. coli O157 at day 137 (P = 0.03), when a prevalence peak was observed and 50% of the isolates were detected. Multiplex PCR assays were conducted for some virulence genes. PCR results indicated that all except one isolate possessed at least the Shiga toxin gene stx2. MICs for 12 antibiotics were determined, and eight oxytetracycline-resistant E. coli O157 strains were identified. Antibiotic-resistant strains were considered a distinct subpopulation of E. coli O157 by pulsed-field gel electrophoresis typing. Seven of these antibiotic-resistant strains were isolated early in the study (on or before day 25), and among them two were also hypermutable as determined by rifampin mutation frequencies. The proportion of hypermutable strains among E. coli O157 isolates remained relatively constant throughout the study period. These results indicate that the use of growth-promoting agents and antibiotics in beef production may increase the risk of environmental contamination by E. coli O157.