The use of allium extract containing propyl propane thiosulfonate (PTSO) as hen feed supplement was evaluated to demonstrate its positive effect on egg production and intestinal microbiota modulation. The study was carried out on 90 laying hens whose feed was supplemented with allium extract for 28 days. Nutritional properties of eggs were not affected, whereas an improvement in productivity was observed based on the increase weight of eggs. In addition, a modulator effect on intestinal microbiota was confirmed by the increase in Lactobacillus spp. and Bifidobacterium spp., as well as by the reduction in Enterobacteriaceae populations. Finally, the preservation of egg composition was checked by monitoring the content of PTSO, using a new analytical method consisting of the use of solid phase extraction and ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Consequently, based on current results, Allium spp. extract rich in organosulfur compounds such as PTSO added to the diet had a beneficial effect on the microbiota and would seem to be a possible alternative to increase productivity, while not affecting the biochemical composition of egg. However, further studies on the effects of allium extract as feed supplement are necessary.

Allium derivative propyl propane thiosulfonate (PTSO) is a new additive for animal feed which improves animal health when used as an alternative to antibiotic growth promoters. Despite the effort of the European Union to ensure the control of animal feed alterations, information available on this new additive is sparse and analytical methods used for its monitoring have limited reach. Moreover, existing analytical methods exhibit shortcomings when applied to other matrices or when attempting to measure low concentration levels. This paper describes for the first time that PTSO reacts instantaneously with cysteine (CYS) and glutathione (GLU) generating s-propyl mercaptocysteine (CSSP) and s-propyl mercaptoglutathione (GSSP), thus explaining the limitations of previous methods when applied to feed with high concentration levels of CYS and GLU. Therefore, an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method combined with a sample treatment based on simple solid–liquid extraction with methanol is proposed for the monitoring of PTSO, CSSP and GSSP in a wide range of animal feed samples including those for pigs, piglets, broilers, hens, rabbits and partridges. This method provides a simple, robust and efficient alternative for the determination of this additive. Matrix-matched calibration curves were established for PTSO, CSSP and GSSP and limits of detection (LODs) and quantification (LOQs) were estimated, being lower than the ones previously reported for PTSO when using HPLC-UV. The relative standard deviation of the whole analytical method was lower than 10% in all cases, while recoveries ranged from 93% to 104%.

This paper evaluates the bioavailability of allium derivative propyl propane thiosulfonate (PTSO) in the pig gastrointestinal tract by means of an in vitro dynamic gastrointestinal tract simulator system (GITSS). The GITSS is based on a membrane bioreactor comprising a continuous stirred-tank reactor connected in series to a continuous plug-flow tubular reactor. Bioavailability values have been evaluated for different vehiculization strategies, including mere carriers such as polyethylene glycol sorbitan monooleate (a nonionic surfactant also known as Tween 80) and encapsulation matrices (β-cyclodextrin vs. mono- and di-glycerides of edible fatty acids mixed with hydrogenated sunflower oil) and compared with the absorption of free PTSO. The net absorbed amount of PTSO in the GITSS when Tween 80 was used as a carrier was over 3.5 times higher than the one for free PTSO. Neither the encapsulated PTSO in β-cyclodextrin nor by means of mono- and di-glycerides of fatty acids plus a vegetable oil succeeded to improve absorption values for free PTSO. These promising results indicate that Tween 80 provides an interesting and high resistance to the PTSO molecule against the simulated digestive conditions in the stomach, and thus it enables favorably the subsequent absorption process of PTSO along the intestine.