The objective of the present study was to detect and quantify the level of isoflavones (genistein and daidzein) in different chicken feeds which were formulated based on BIS standards 2007. Six samples of chick mash, chicken grower and chicken breeder feeds used for analysis were procured from poultry feed mills and the samples were incubated with β-glucuronidase for better detection of different isoflavone aglycones and metabolites. The extracted isoflavones were purified by C18 solid phase extraction and analysed by high performance liquid chromatography (HPLC). The mobile phase composition, gradient elution programme and injected volume were optimised for separation efficiency and sensitivity. It is an accurate and precise analytical methodology which shows good reproducibility and can be easily adapted to detect isoflavones.

The average genistein concentrations were 279.85 ± 1.30, 84.48±1.97 and 148.26 ± 1.64 µg/100 g in chick mash, chicken grower and chicken breeder respectively. However, the average daidzein concentration was in 276.29 ± 1.57 µg/100 g chick mash, 51.67±1.11 g/100 g in chick grower and 153.16 ± 1.21 µg/100 g in chick breeder. The findings indicated that the concentration of genistein and daidzein in the feeds was positively correlated with the level of soybean in the feed since it is the predominant source of isoflavones.