Among forbidden substances included in the European Union legislation, endogenous steroids constitute a challenge in the framework of veterinary Official Monitoring Plans. They can be naturally present in body fluids at variable levels depending on the species, sex and age of the animals. Considering the significant advances achieved in breeding conditions and in the selection of producing traits in meat cattle, the aim of this study was to verify by analytical method, in veal calves housed under controlled conditions, if the level of natural steroids hormones assumed as physiological are still actual. The second aim of the study was to verify if the normal histological pattern of growth promoters in target organs is influenced accordingly. Bovine male sex organs are currently analysed in the frame of the Italian histological plan to monitor illicit treatments trend, highlighting microscopic, induced alterations. The levels of 17β-estradiol and progesterone residues resulted under the Limit of Quantitation of the approved official methods and the level of testosterone resulted below the level stated in the Italian Ministerial Decree in force. Male target organs appeared within the limits of the standard histological features.

The use of anabolic–androgenic steroids (AASs) as growth promoters in farm animals is banned in the European Union, representing both an illicit practice and a risk for consumer health. However, these compounds are still illegally administered, often in the form of synthetic esters. This work aimed to characterize significant coding RNA perturbations related to the illicit administration of testosterone and nandrolone esters in fattening pigs. A total of 27 clinically healthy 90-day-old pigs were randomly assigned to test and control groups. Nine animals were treated with testosterone esters (Sustanon^®) and other nine with nandrolone esters (Myodine^®). At the end of the trial, liver samples were collected and analyzed using RNAseq, allowing the identification of 491 differentially expressed genes (DEGs). The transcriptional signature was further characterized by a smaller sub-cluster of 143 DEGs, from which a selection of 16 genes was made. The qPCR analysis confirmed that the identified cluster could still give good discrimination between untreated gilt and barrows compared to the relative testosterone-treated counterparts. A conclusive field survey on 67 liver samples collected from pigs of different breeds and weight categories confirmed, in agreement with testosterone residue profiles, the specificity of selected transcriptional biomarkers, showing their potential applications for screening purposes when AAS treatment is suspected, allowing to focus further investigations of competent authorities and confirmatory analysis where needed.