Effect of seasonal variations and lactation times on aflatoxin M1 contamination in milk of different species from Punjab, Pakistan

During October 2009 to September 2010, aflatoxin M1 (AFM1) levels were analyzed by HPLC-FLD in 356 milk samples of different lactating species (buffalo, cow, goat, sheep and camel) from Punjab (Pakistan). Recoveries of AFM1 ranged from 92 to 97% and the limit of detection (LOD) was 0.004 μg/L. For all lactating species the mean concentration of AFM1 was significantly higher in winter season than in summer (p < 0.05). The results showed that 55, 56, 32, 58 and 27% of winter milk samples of buffalo, cow, goat, sheep and camel exceeded the EU maximum limit (0.05 μg/kg), compared with 38, 33, 21, 36 and 14% of summer milk samples, respectively. For all lactating species the mean concentration of AFM1 was significantly higher in morning milks than in evening milks (p < 0.05). The percentage of morning milk samples exceeding the EU maximum limit was 72, 67, 69, 71 and 44% for buffalo, cow, goat, sheep and camel, while for evening milks percent non compliant rates were 39, 30, 18, 33 and 25%, respectively. The level of AFM1 tended to be higher in animal species fed mainly on concentrate mixtures (buffalo and cow) than in other species grazing on fresh greens.

► We analyzed aflatoxin M1 in milk for seasonal and lactation variations. ► Summer milk samples were less contaminated than winter milks. ► AFM1 excretion rate was higher in morning milks than in evening milks. ► AFM1 was higher in animals fed on concentrates than those grazing on fresh greens. ► Milk samples from Pakistan exceeded EU maximum limits in many instances.