Gossypol content of cotton free commercial feed for dairy cows

Gossypol is a yellow pigment occurring in all parts of cotton plants, with the highest levels found in seeds, and it exhibits a variety of toxic effects. Few data are available on the content of gossypol in the commercial complementary feed and in feed raw materials. The present study was focused on the investigation of the presence of free gossypol in commercial complementary feed not containing cotton. A total of 50 samples of commercial complementary feed for dairy cows were performed in 29 feed mills both using and not using cotton as feed material. The free gossypol contamination resulted under the detection limit of the technique (4 mg/kg) in 12 out of 50 samples analysed and ranged from 4 to 20 mg/kg in 28 samples. In 10 samples the level of free gossypol ranged from 20 to 29.5 mg/kg. Average contamination of samples was 12.2±9.2 SD mg/kg. No significant difference (P=0.571) was shown in free gossypol concentration between feed produced in cotton free plants and in plants where cotton is used as feed material. Free gossypol content detected in the present study allows considering complementary feed for dairy cows not at risk. On the other hand, the detection of free gossypol in cotton free complementary feed, probably attributable to cross contamination of feed materials upstream of the feed mill, should be further investigated.