Lupin varieties with a low content of quinolizidine alkaloids (QAs) like blue sweet lupin (BSL) have long been used as a protein source for dairy cows. A health concern for humans may arise from the transfer of acute toxic QAs from feed into cow's milk. This study is the first to quantify the transfer of QAs from BSL into cow's milk with experimental and modeling methods. Four lactating dairy cows were subjected to two 7 day feeding periods with 1 and 2 kg/d BSL, respectively, each followed by a depuration period. BSL contained 1774 mg/kg dry matter total QAs. Individual milk samples were taken twice daily and QA contents in feed and milk determined with liquid chromatography-tandem mass spectrometry. Transfer of QAs into the milk was already seen with the administration of 1 kg/d BSL, with differences in transfer rates (TRs) between individual QAs. A toxicokinetic model was derived to quantify and predict QA feed-to-food transfer. For the four most prominent QAs, our model shows an α-half-life of around 0.27 d. TRs were obtained for six QAs and were between 0.13 (sparteine) and 3.74% (multiflorine). A toxicological assessment of milk containing QAs as measured in this study indicated a potential health concern.

Hypoglycin A (HGA) and methylenecyclpropylglycine (MCPrG) are formed by some maple trees (Acer species) and have been associated with incidences of atypical myopathy among horses in pastures. In this work, a simple and sensitive ultra-performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS) method without derivatization was developed for the quantification of HGA and MCPrG in maple samples and validated according to EU guidelines. The LOQ presented here for HGA (16.4 µg/kg) is considerably lower than the lowest published LOQ (500 µg/kg). This method confirms that sycamore and box elder maple contain considerable amounts of HGA and MCPrG. In addition, the presence of the dipeptides hypoglycin B and γ-glutamyl-MCPrG in these two maple species is shown using high-resolution MS. This is the first report on the presence of these dipeptides in maple since 1973. The presence of HGB and γ-glutamyl-MCPrG could change the way we understand animal intoxication following the ingestion of maple.

Hypoglycin A (HGA),methylenecyclopropylglycine (MCPrG),hypoglycinB (HGB), and & gamma;-glutamyl-& alpha;-(methylenecyclopropyl) glycine(& gamma;-glutamyl-MCPrG) are secondary plant metabolites occurringin sycamore maple (Acer pseudoplatanus) as well as several other Sapindaceae (e.g., Blighiasapida). By interfering with energy metabolism, theymay cause severe intoxication in humans and other species. However,to date, there is not enough data available concerning the intake,metabolism, or excretion of sycamore maple toxins in dairy cows. InMay 2022, five cows were observed over four days, when they had firstaccess to a pasture with two sycamore maples. Grazing of their seedlingsthat grew numerously in between the pasture plants was monitored bydirect observation. Milk samples were drawn both from individual cowsand from the bulk tank. Spontaneous urine samples were collected fromall cows on day 3 after access to the pasture. Seedlings (100 g) weresampled on the pasture and analyzed, together with milk and urinesamples, for sycamore toxins and their metabolites using liquid chromatography-tandemmass spectrometry and liquid chromatography-high-resolution mass spectrometry.Cows ingested sycamore seedlings while grazing. Values of HGA in milkwere below the limit of quantification. However, metabolites of HGAand MCPrG were detected in individual milk samples already at theend of the first day of grazing. Urine samples of all five cows showedhigher concentrations of conjugated HGA and MCPrG metabolites thanin milk. Observations suggest that dairy cows may have a low susceptibilitytoward sycamore maple toxins. However, whether this could be attributedto foregut fermenting species in general requires further elucidation.