Carryover of maduramicin from feed containing cross-contamination levels into eggs of laying hens

Ionophore coccidiostats - disposition kinetics in laying hens and residues transfer to eggs

Poultry production is linked with the use of veterinary medicinal products to manage diseases. Ionophore coccidiostats have been permitted for use as feed additives within the European Union (EU) for the prevention of coccidiosis in various species of poultry with except of laying hens. The presence of chemical residues in eggs is a matter of major concern for consumers' health. Despite such prohibition of use in laying hens, they were identified as the most common non-target poultry species being frequently exposed to these class of coccidiostats. Many factors can influence the presence of residues in eggs. Carryover of these class of coccidiostat feed additives in the feed of laying hens has been identified as the main reason of their occurrence in commercial poultry eggs. The physicochemical properties of individual compounds, the physiology of the laying hen, and the biology of egg formation are believed to govern the residue transfer rate and its distribution between the egg white and yolk compartments. This paper reviews the causes of occurrence of residues of ionophore coccidiostats in eggs within the EU with special emphasis on their disposition kinetics in laying hens, and residue transfer into eggs. Additional effort was made to highlight future modeling perspectives on the potential application of pharmacokinetic modeling in predicting drug residue transfer and its concentration in eggs.

Risk of residues of toltrazuril sulfone in eggs after oral administration - Could setting maximum residue limit be helpful?

A depletion study of toltrazuril and its metabolites was performed using 20 hens medicated via drinking water for two days in a dosage of 7 mg kg^-1 per kg body weight. Afterward, eggs were collected for 42 days. Residues were analyzed in whole eggs and yolk and whites. Toltrazuril sulfone was found to be the most predominant in all matrices, the highest concentration was found in the yolk - 5567 µg kg^-1, followed by whole eggs samples - 4767 µg kg^-1 and egg whites - 532 µg kg^-1. On last day toltrazuril sulfone were still detected - 22.5 µg kg^-1. 70 days is required to concentration of toltrazuril sulfone reach zero. Administrating toltrazuril before the laying phase can pose a risk of residues of toltrazuril sulfone in eggs. Setting Maximum Residue Limit could reduce the risk of non-complaint samples and ensure the safety of consumers, but still requires 44 days of the withdrawal period.

Deposition, depletion, and potential bioaccumulation of bisphenol F in eggs of laying hens after consumption of contaminated feed

Increasing concerns over bisphenol A (BPA) as an endocrine disrupting chemical (EDC) and its adverse effects on both humans and animals have led to the substitution by structural analogs, such as bisphenol F (BPF), in many application areas. Information regarding to the carry-over of this emerging chemical in farm animals is essential for legislation and risk assessment purposes. In this study, a large-scale number of animal experiments were designed to investigate the transfer of BPF from feed to eggs. One control and three experimental groups of laying hens (72 hens per group) were fed with basal diets and BPF-contaminated feed at concentration levels of 0.1, 0.5 and 2.5 mg kg^-1, respectively, for two weeks. The hens were then fed with BPF-free diets for a further four weeks. Eggs were collected daily, and separated into egg yolk and white for BPF analysis. The effects of different levels of BPF exposure on laying performance followed a non-monotonic dose-response curve, since low level BPF (0.1 mg kg^-1) exposure did increase the laying rate, mean egg weight and daily feed intake, while high level BPF (2.5 mg kg^-1) exposure showed a decreasing trend. BPF residues were detected in both egg yolks and whole eggs after two days of administration, and plateau phase was achieved within 9-18 days. There are clear linear dose-response relationships between the plateau BPF concentrations in feed and eggs. The residue of BPF was found mainly in egg yolks with conjugated form and depleted slowly (still detected 21 days after feeding the BPF-free diet of the high level group). Mean carry-over rate of 0.59% BPF from feed to eggs was obtained. Compared with the carry-over rates of PCBs and dioxins, BPF showed a relatively minor trend of bioaccumulation in eggs. To the best of our knowledge, this is the first report on the deposition, depletion, and bioaccumulation study of bisphenols in farm animals. The quantity of data can therefore be helpful in the frame of risk assessment, especially for a comprehensive estimation of consumer exposure to the residues of bisphenols.

Coccidiostats in milk: development of a multi-residue method and transfer of salinomycin and lasalocid from contaminated feed

A confirmatory multi-residue method was developed for the determination in milk of 19 coccidiostats (amprolium, arprinocid, clazuril, clopidol, decoquinate, diclazuril, ethopabate, halofuginone, lasalocid, maduramicin, monensin, narasin, nicarbazin, nequinate, robenidine, salinomycin, semduramicin, toltrazuril sulfone and toltrazuril sulfoxide). Sample preparation utilising extraction with organic solvent and clean up by SPE and freezing was found reliable and time-efficient. Optimised chromatography and MS conditions with positive and negative ESI achieved sufficient sensitivity and selectivity. Validation experiments has proven method usefulness for routine analysis of coccidiostats in milk samples. An on-farm study conducted on dairy cows fed with experimentally contaminated feed with salinomycin and lasalocid showed negligible transfer to milk. No residues of lasalocid were found in collected samples. Salinomycin was found only in 5 of 168 samples analysed, while the concentrations of salinomycin in those samples (0.119-0.179 µg kg^-1) was significantly below the limit of salinomycin in milk set by European Union legislation. Such low concentrations of both coccidiostats cannot be explained by conjugation during dairy cows' metabolism, as shown by experiments with enzymatic hydrolysis.

Deposition and depletion of decoquinate in eggs after administration of cross-contaminated feed

Decoquinate, a chemical coccidiostat used as a feed additive, can occur in eggs due to cross-contamination of feedstuffs for laying hens. An experiment was designed to assess the transfer of decoquinate to hen eggs and its distribution between egg yolk and egg white. Hens were given the feed containing decoquinate at a cross-contamination level (0.34 mg kg(-1)) and collected eggs were analysed using an LC-MS/MS method. The plateau level was reached on the eighth day of the experiment and averaged 8.91 µg kg(-1), which is far below the maximum level established at 20 µg kg(-1) for whole eggs. Decoquinate was deposited mostly in egg yolks (26.2 µg kg(-1)) and did not deplete completely during 14 days of administration of decoquinate-free feed. The results confirmed that administration of cross-contaminated feed is associated with very low risk of non-compliant residue levels of decoquinate in eggs.

Deposition and depletion of maduramicin residues in eggs after oral administration to laying hens determined by LC-MS

The coccidiostat maduramicin has been approved as a feed additive for chickens and turkeys, although it is prohibited for use in laying hens. In the present study, laying hens were divided into three groups and fed for 14 days with medicated feed containing maduramicin, at three different concentrations: 50, 100 and 500 µg kg(-1). Eggs were collected during treatment and for 26 days after the end of feeding with medicated feed. Maduramicin residues were found exclusively in egg yolk, with the highest concentration in egg yolk of 459 µg kg(-1) for the highest dose. The maximum concentration of maduramicin in whole egg was 16.6 µg kg(-1) for the group receiving feed containing the maximum permitted level of maduramicin in feed (50 µg kg(-1)). The half-life of elimination of maduramicin, calculated for post-treatment days 1-10, was 6.5 days. Twelve days after drug administration, the concentration of the maduramicin in egg yolk for Group 3 (fed with 500 µg kg(-1) maduramicin) still exceeded 20 µg kg(-1), while the concentrations for Groups 1 and 2 were 1.2 and 2.7 µg kg(-1), respectively.

Distribution of semduramicin in hen eggs and tissues after administration of cross-contaminated feed

Semduramicin is an ionophore coccidiostat used in the poultry industry as a feed additive. Cross-contamination of feeds for non-target animals with semduramicin is unavoidable. However, it is not known whether undesirable residues of semduramicin may occur in food after cross-contaminated feed is administered to animals. The aim of the work was to determine the levels of semduramicin in hen eggs (yolks and albumen) and tissues (liver, muscle, spleen, gizzard, ovarian yolks and ovaries) after administration of feed contaminated with 0.27 mg kg(-1) of this coccidiostat. The residues were determined using LC-MS/MS. The distribution pattern confirmed the high lipophilicity of semduramicin. Residues were found mainly in egg yolks (28.8 µg kg(-1)), ovarian yolks (19.5 µg kg(-1)) and liver (2.57 µg kg(-1)), while hens' muscle was free from semduramicin (LOD = 0.1 µg kg(-1)). Among edible tissues, the maximum level (2 µg kg(-1)) was exceeded only in the liver.