# Determination of Eleven Veterinary Drugs in Chicken Meat and Liver
## 3 Results and Discussion  
### Feed Additives  
Table 1 shows the eleven evaluated antimicrobials in this study in chicken meat and liver as demanded by the Gulf Technical Regulation to attend Middle East requirements [5]. All complied to the international standards as well as the concentration found in this study for all analytes were below the limit of quantification (LQ). Regarding the domestic market, Brazilian MAPA collects samples annually from Federal Inspected (SIF) meat industries and monitors the feed additive residues through the PNCRC for the chains of beef, pork, goat, nutton, equine, rabbit, poultry, ostrich meat, and milk, fisheries, honey, and eggs. Usually, MAPA monitors 7 from the 11 antimicrobials displayed in Table 1 (see columns 5-7), however sometimes in a different matrix, not only chicken meat. For instance, bactracin, colistin and tianulin are often monitored in eggs, however MAPA prohibited the import and manufacture of colistin, through Normative Instruction 45/2016, for the purpose of a zootechnical additive that improves animal performance, while the others are allowed; and spectinomycin is monitored in kidneys, either for internal or external market. Nevertheless, when Brazil exports chicken meat to other countries, the legislation of the specific importer country must be followed and sometimes other veterinary drugs are demanded in different matrices, as happened in the present research. For instance, Brazilian MAPA published an ordinance (87/2018) recognizing the private protocol of the Gulf Technical Regulation to attend Middle East requirements [5,7]. Most of the chemical residues monitored in chicken meat production by Brazilian PNCRC (Table 1) refer to antibiotics used as prophylactic agents, so these compounds are demanded and analyzed by the main importing countries. For instance, tylosin residues were below the LQ = 25 \(\upmu\)g/kg in all 300 chicken meat samples analyzed herein. Although this compound is regulated for meat worldwide, varying from 100-200 \(\upmu\)g/kg, in Brazil, a lot of matrices are analyzed regarding tylosin residues, such as chicken meat, kidney, egg, milk, and honey. Tylosin is a macrolide antibiotic, added to feed or to water and is registered exclusively for veterinary use (pigs, chickens, turkeys, and cattle) in many countries, being effective against gram-positive bacteria, Mycoplasma and _Chlamydia_ spp. [3]. For all 300 samples of amoxicillin (AMX) analyzed in this study, all were below LQ (10 \(\upmu\)g/kg). Usually, Brazilian MAPA analyzes 600 samples per year of this additive residue in chicken meat samples collected throughout the country. AMX is a semisynthetic \(\beta\)-lactam antibiotic which belongs to the aminpenciillin group. AMX has a broad antimicrobial spectrum, low toxicity when compared to other veterinary drugs and a relatively good absorption rate. It is of low cost and applied in poultry farming. However, AMX residues may be deposited in tissues and this antibiotic is considered in most monitoring plans in Latin America [13]. Colistin residues in this study showed concentration values below 75 \(\upmu\)g/kg in chicken meat, while MAPA has in its PNCRC scope 300 samples to be analyzed in eggs with MRL = 300 \(\upmu\)g/kg. Other legislations worldwide establish MRL in meat to be MRL = 150 \(\upmu\)g/kg, while Canada and USA do not use this additive, nor Brazil in meat-producing animals. Colistin is one of the most effective antimicrobial agents and is able to inactivate 100% _Salmonella_ spp. in poultry [14].