Survival of three Bifidobacterium animalis subsp. lactis strains is related to trans-vaccenic and a-linolenic acids contents in organic fermented milks a b s t r a c t This study aims at relating the survival at 4 C for 28 days in organic and conventional fermented milks of three strains of Bifidobacterium animalis subsp. lactis (BB12, B94 and BL04), in co-culture with Strepto-coccus thermophilus TA040 and Lactobacillus bulgaricus LB340, to milk fatty acids profile. Cultivability after 28 days of cold storage was improved in organic fermented milks as compared to conventional products, with slight differences among strains. In addition, the poly-unsaturated fatty acids fraction was higher in organic products, as well as the relative trans-vaccenic (TVA) and a-linolenic (ALA) fatty acids contents that were respectively 1.7 and 2.4 times higher in organic than in conventional fermented milks. From these results, it was concluded that elevated levels of TVA and ALA, together with a lower ratio between linoleic acid and a-linolenic acid, as found in organic products, improved the survival of the bifidobacteria during chilled storage.